THE SEISMIC SEA WAVE OF 22 MAV 1960 ALONG THE CHILEAN COAST
Immediately following the earthquake and the tsunami that struck Southern Chile and inflicted extensive damage in ten provinces, parties of scientists (principally geologists) began to investigate the causes, the damage, and the possibilities of preventing or ameliorating the effects of future seismic movements. Scientists and engineers arrived from Japan, Mexico, North America, France, and other countries and, with the Chileans, began to study the situation in the hope of encountering some means by which earthquakes can be predicted and of developing techniques for preventing the great destruction caused by these phenomena.
The Chilean Navy put in movement practically all of its boats to help the villages that were affected, to make hydrographic studies that would permit navigation in the wide zone affected, and to give security to the ships of war and merchant vessels cooperating with them. Principally this work was done in the mouths of rivers, in rivers, in bays, in canals, and in all those places that might have suffered changes as a result of the earthquake.
The Oceanographic Section of the Navys Department of Navigation and Hydrography was put into action to collect the maximum amount of information possible concerning the seismic sea wave; the maritime authorities helped with this study in each place. They succeeded in collecting information that has permitted a general study of the phenomena.
The number of tidal-wave victims has riot been determined. and very probably the number of lives lost never will be known. Nor is there sufficient information to determine the locations of the epicenters nor to formulate any theories concerning the formation of the maremotos (seismic sea waves).
With the object of maintaining a predetermined order in the description of the phenomena, the material is arranged geographically, beginning in Aysen (the southernmost point at which effects were felt and from which data was obtained) and going north. (Punta Arenas and its immediate zones were not affected, as can be seen from examination of the tidegram from that place.)
All the times mentioned here are official Chilean time, International Zone Plus Four, except when expressly indicated. In general, the data have been compiled by people who have riot had a scientific education, but who have done all possible to give complete and accurate information.
PART I. GENERAL DESCRIPTION
At 0604 hours on 21 May, a great earthquake with its epicenter in the zone of Conceptcon caused extensive damage to the towns in that area. As any earthquake that occurs near the coast may give rise to a maremoto, there existed the possibility that one may have been produced. In fact, the tidal record at Valparaiso registered a small alteration beginning at about 0900, consisting of waves 20 to 30 cm in height with a period of 20 to 25 minutes (figure 1 cc to 1 it: all tidal records are in pocket at rear of this number). This abnormal activity continued all during the day and part of the night but decreased gradually.
The Department of Navigation and Hydrography, in compliance with its obligation as a member of the alarm system for Pacific tidal waves, contacted the central headquarters of this system in Honolulu, keeping them constantly informed. The earthquake also had registered on the seismo graphs of the Magnetic Observatory of Honolulu, and the Observatory had sent immediate inquiries to those recording stations around the Pacific who they thought might have registered abnormal waves.The state of alert began in the central stations of the alarm system in Hawaii at 0645 hours and terminated at 2040 hours, at which time it was demonstrated thatthe earthquake of Conception had not given origin to a tidal wave. During the state of alert, cables were sent to various points in the Pacific from the central office inquiring about abnormalities.
All the tidal meters in Chile from Valparaiso to the north registered small abnormalities with the same characteristics as those at Talcahuano, but this, in general,went almost unnoticed, and their passage neither damaged nor interrupted maritime operations. As a precaution, a permanent watch was maintained at the tidal station of Valparaiso to verify any possible further abnormalities.
At approximately 1510 hours on 22 May, there was another earthquake of great proportions, with an epicenter apparently in the province of Llanquihue, that caused grave damage in the provinces between Conception and Chiloe. The cities most affected were Puerto Montt, Valdivia, Ancud, Castro, and Corral. This earthquake originated a maremoto of such proportions that it destroyed all of the ports of this zone, producing tremendous damage. The first information received was from Lebu and referred to waves between 3 and 4 meters in height that were damaging the port. Shortly thereafter, notices began to arrive, confused by the difficulty of communication, that referred to successive marine waves that were causing devastation in Ancud, Bahia Mansa, Corral, Puerto Saavedra, etc. Upon receiving this information at 1630 hours, the Department of Navigation and Hydrography sent a cable to Honolulu, giving them the information needed to put the entire system into a state of alert. A short time afterwards, new cables were sent with more concrete information. The tide gage in Valparaiso began to register the first waves at 1613 hours, when the water rose rapidly some 74 cm in 16 minutes, lowering again rapidly a short time later. The successive rising and falling movements continued, as shown in figures 1 cc-1 ii.
The alarms of the seismographs sounded at 1538 hours in the Magnetic Observatory of Honolulu. Five minutes before the arrival of the cable from Valparaiso, the observatory sent the following bulletin:
"This bulletin is a tidal wave alert. A violent earthquake has occurred in Chile,the third in that area in the last 36 hours. It is possible that it has generated a large tsunami. Although we have as yet no data, we are awaiting information from Valparaiso and from Balboa. If a tidal wave has been originated it should arrive about midnight Hawaiian time today at the Island of Hawaii and 30 minutes later at the Island of Oahu. New information will be given as soon as more data is available."
Later, new bulletins were sent with information received from Valparaiso and from the various islands that were being affected by the tsunami. The picture was being completed at 0047 hours, 0 hours after the earthquake, and the following message was sent from Hawaii:
"This is a tidal wave alert bulletin. A violent earthquake in Chile has caused a tidal wave that is radiating in all directions over the Pacific Ocean. It is estimated that the first wave will reach the Island of Hawaii at midnight Hawaiian time and 30 minutes later at the Island of Oahu. Its destructive effects will last several hours.The intensity of the wave cannot be predicted. The southern part of Hawaii will he the first to be affected and will be the first indication of the damage that might be produced in other parts and other islands of the Hawaiian group. The times have been calculated for the arrival at other Pacific islands based on the best data obtainable; they are not very exact: Tahiti 0230 hours, Christmas Island 0400 hours, Samoa 0500 hours, Fiji and Canton 0600 hours, Johnston 0700 hours, and, Midway 0830 hours."
The interchange of communications continued constantly, and data of the arrival of the tidal wave were received in the following manner: At 0330, a cable was dispatched from Tahiti advising of the arrival of the first wave; at 0430, Samoa informed of the arrival of the first wave; at 0458, Christmas Island informed of the arrival of the first wave; etc.
The messages arrived one after another, informing of the advances of the tidal waves. At 0654, the first wave arrived at the Hawaiian Islands, producing great damage in Hilo; but, the activity of the Magnetic Observatory at Honolulu did not cease. At 1211 on 23 May, the state of alarm oil the Hawaiian Islands terminated, but the waves of the tsunami continued their destructive voyage until they were stopped and then reflected by the coasts of Japan, Russia, New Zealand, Australia, etc.
PART II. DESCRIPTION BY PORTS BETWEEN AYSEN AND LOTA, INCLUD1NG THE ISLANDS JUAN FERNANDEZ AND PASCUA
Aysen: One might think that the effects of the tsunami might not have been noticed in Avsen, its river, and the nearby ports of Chacabuco, Aguirre, and Me linka, because they are located in a network of canals (figure 2). Nevertheless, three waves were felt in these places.
The first wave arrived at 1710 at Melinka, almost two hours after the earthquake. Some material damage was produced by the inundation of several houses, among them the office of the Alcaldia de Mar (equivalent to harbor master). No estimation of the height of the first wave was made.
At 1720, the effects of this wave were noted in Puerto Aguirre, where it was estimated that it reached a height of a little more than 3 meters above the level of the sea. At 1730 the wave arrived at the mouth of Rio Avsen (figure 3), where, according to estimates, the water rose 3 meters above the average level of the sea. The calculation is based oil the fact that the wave arrived at the time of low tide and succeeded in inundating houses along the river banks above the level of the highest tides. Ten minutes later, the effects of this wave were felt in Aysen, reaching a level of 1 meter above the average. Water rose as in a very rapid tide, producing an inundation without breakers.
The second wave arrived at Aysen at 1900 hours, 1 hour and 20 minutes later. The height of this wave was estimated at 1.60 meters at the bar at the mouth of the Rio Aysen and at 0.8 meter in the port. The third wave arrived at Aysen at 2300 hours, 2 hours later, but was not observed at the bar because everyone had been evacuated by the motor ship Sebastiana.
A look at the map (figure 2) permits an appreciation of the canals through which the wave had to go and the great number of islands that Were affected. No more information exists for this practically uninhabited area.
Between Melinka and Puerto Aguirre, separated by some mild in a straight line, the wave raced with a velocity of approximately 460 knots. This value should be considered with reserve, because the hour in which the wave arrived at each one of these ports is only approximate. But in any case its velocity was considerable.
The 42 miles between Puerto Aguirre and the bar at Rio Aysen was covered by the wave in about 10 minutes, giving, at the very least, a velocity of 2.50 knots.
The 7 miles from the bar at Rio Aysen to Puerto Aysen was run in approximately 10 minutes. This world give a velocity of about 40 knots. The average depth of the Rio Aysen is 6 meters, but at the bar its depth is not in excess of 3.5 meters.
On the map of the mouth of the Rio Aysen (figure 3), we have crosshatched the inundated zone, and the changes suffered by the sand banks have been indicated when they could be determined. The map of the Rio Aysen is not completed because the zone inundated along the river banks was very small.
Soundings over the river bar indicate the depth has increased about 0.5 meter and the point south of the port bank has disappeared. On the other hand, the starboard bank has increased. It is probable that the alteration of the hanks was due to a comhination of the forces of the earthquake and the tidal wave. The earthtluake could have brought about a settling or compaction of the sediments and the tsunami a redistribution of the sand, sweeping away a part of it and carrying the rest toward the south.
According to information from the Maritime Authority of Aysen, the banks of the river there have not undergone changes with respect to the average level of the tide.
Isle Guafo: The Island of Guafo, situated 20 miles to the south-southwest of Isla Chiloe (figure 4), consists of forested hills. The coast around practically all its perimeter consists of banks 60 to 100 meters in height. The lighthouse of Guafo is on Punta Weather (figure 5) 146 meters above the sea.
About 10 minutes after the earthquake, the personnel of the lighthouse saw that the sea was retiring slowly toward the west leaving about 600 meters of the sea floor exposed to view. At the same time that the sea was receding, a big Nvave was forming to the west of the lighthouse. This wave soon advanced upon the island with great velocity.
The first wave was followed by three other large waves before the phenomenon began to decline. The waves reached the greatest height inside Caleta Rica (figures 5 and 6), and their direction was from west to east. After striking the coast of the islands, waves were reflected toward the northeast.
Two days later, the personnel of the lighthouse went to inspect the cliffs and were able to observe that the water had reached a height of 10 meters.
As a consequence of the earthquake, Isla Guafo was raised 3 to 4 meters. This is made evident in two ways: First, the old dock area, consisting of a rock with a flat upper part, is now useless because it has been raised to a greater height over the sea and is now surrounded by outcrops of rocks that were previously deeply submerged. Second, the Island of Giiafito (figure 6) is now joined to the main island by a beach some 40 meters wide that is not covered by even the highest tide.
Quellon: Information concerning this port, situated at the extreme southeast of the Island of Chiloe, is very scarce (figure 4 and 7).
About 5 minutes after the earthquake, the sea retired some 50 meters and then began to rise slowly, arriving at its maximum 7 hours later. There never was much wave action and it appears that the rise of the water obeyed the tides and was more like a tide than a maremoto. The water inundated houses along the avenido Costanera. In one zone, the sea rose about 22 meters and was detained by a high wall; in another, it reached 150 meters.
The most noticeable effect was that after the earthquake the tides reached places they had not reached before. Based upon this and other observations, it is calculated that this part of the island experienced a sinking of about 2 meters. Figures S-13 show the height reached by the tides on 4 and 5 Augurst 1960, the day in which the highest tides of the year are produced along this part of the Chilean coast.
Achao: In Achao (figure 4 and 14), the tidal wave began about .5 minutes after the earthquake. The water seemed as if it were boiling, and it formed several currents that whirled through the Dalcahlie and Quinchao canals. Some moments later, a wave seen forming about a mile in front of the port began advancing toward the coast. Two more waves formed in approximately the same area a little later and followed the first one in. The third wave arrived with the greatest force, but it did no damage because the earthquake occurred at about the time of low tide. The water of the third wave reached the line of ordinary high tides. The inhabitants of Achao estimated the height of the wave as about 2.5 meters.
There was not much accord between the people interviewed in Achao as to whether the first effect of the sea wave was a rise or a withdrawal of the sea.
As in Quellon, it is certain that the Island of Quinchao, where the port of Achao is located, sank. The actual amount of sinking has not been estimated, but evidence of sinking is clear. Before the earthquake, the port was surrounded by a beach about 300 meters wide. The beach is now only about 200 meters wide. The tides at syzygy inundated parts of the waterfront. Water reached the main street (figure 14), athing that had never happened before. Some houses near the sea have had to be evacuated.
Linao: Information from this port is scarce (figure 4). About 10 minutes after the earthquake, the sea withdrew. Three waves were formed, with heights estimated at 0.5 meter.
After the earthquake, the tides reached zones to which they had not risen before, inundating the village at each syzygy. This is because of the sinking of the land brought about by the earthquake.
Calbuco: The information obtained from the port of Calbuco (figures 4 and 15) indicates that a tsunami was not observed in this area. After the earthquake, areas were inundated during high tides that had not previously been reached by the water. Sections of the beach, Surgidero La Vega, have sunk.
Puerto Montt: Information obtained in Puerto l Iontt (figure 4) indicates that in this port neither a tsunami nor abnormalities in the tides were noted. A leveling, done by naval personnel, in the neighborhood of Angelmo demonstrated that the land in this locality suffered a descent of about 1 meter.
Ancud: According to information from the Captain of the Port of Ancud (figure 4 and 16), the first evidence of the tidal wave was an abnormal increase of water level of approximately 1 meter about 20 minutes after the earthquake. After this elevation of the water, the sea began to withdraw, first slowly, then rapidly. A current of great intensity was noted in the Gulf of Quetalmahue where waterflowed from the west to the east out out of the gulf. The water then followed a course from south to north as the waters retired from the Bay of Ancud.
The withdrawal was enormous, leaving the bottom completely uncovered within the 5-meter contour. Farther out to sea, low spots were exposed to view, includingseveral deeper places near the coast. It was not possible to establish precisely what the depth was at these points.
The coast of the Bay was struck .50 minutes after the earthquake by a great wave that formed in front of the Bay, in a locality not precisely determined. The direction of this wave was noted as being from north to south. The water that was retiring was absorbed, giving place to the formation of a single uniform mass of water that seemed like a wall. It was estimated that between the lighthouses Punta Coronaand Punta Ahui this mass of water had a height of about 15 meters. This observation was made by several people, among them the master of a sailing ship that had been drawn away during the withdrawal of the sea, who at one moment compared the height of the mass of water with that of the mast of his ship.
In its advance toward the south, the wave struck with great force along the northeast coast of Peninsula Lacui.
In front of Punta Ahui, it was noted that the height of the wave began to diminish to approximately 5 meters as it struck violently against the coast of the Port of Ancud. The violent accumulation of the waters in the Port made it seem that these were displaced following a curve first to the west, then east, south, and north. The wave also penetrated Estero2 Pudeto, but with less intensity because Isla Cochinos protected its entrance.
Later, in the time between the arrival of this great wave and 1700 hours, three more waves of lesser intensity and force reached the coast. These were more or less like rises of the sea caused by an abnormal augmentation of the water.
In fig. 16 we have marked the diverse points that were inundated and have delineated the maximum height reached by the water along the coast from the Bay of Ancud to Estero Pudeto. On the chart of the city, points are marked on the streets at places where the sea reached its maximum penetration.
The greatest distances are represented by points 4 and 10, corresponding to a street with a height of 1.5 meters above the level of the dock, and to a sector that is now below the level of the sea, respectively. The height at the head of the dock is actually 4.7 meters above the average level of the sea. This should give a penetration of the water to a point located more than 6 meters above mean sea level.
In the places between points 4 and 10 the water covered less distance owing to blockage by buildings in the low parts and by a wall formed by the hills that are located a short distance from the seashore.
On the coast south of the Bay, the sea covered a great extent because of the width of the beaches in this region. The water reached the foot of the hills, which here rise vertically.
On the southern and western coast of the Gulf of Quetalmahue, as much as in the northern part, the water rose without force about 1.5 meters.
Along the coast between the lighthouses Punta Corona and Punta Ahui, and along the northern coast of the city between Punta San Antonio and Punta Colorada, the sea struck with the greatest violence, but because the coast was high the waters only intuidated the beaches and the low sectors.
In Estero Pudeto, the water reached the sector indicated in figure 16. The points indicate places where it has been proved authentically that the water reached. In the river itself the sea inundated a great zone of the bank east of the mouth, as marked with arrows on the map.
The waters also covered a great extension of the north coast of the Pudeto. The inundated area cannot be precisely established and for this reason it has not been marked on the map. The Pudeto area and the mouth of the Estero received the effects of the sea wave in an attenuated manner, as has already been mentioned, because of protection given by Isla Cochinos.
In the zone, located between points 5 and 10, of the plain formed by the lowlands, including lands below mean sea level, and by beaches, there existed the suburb of La Arena, composed of numerous wooden houses that were totally washed away. On the other hand, a wooden house situated approximately 25 meters from the shore and 1 meter above the level of the sea did not suffer damage but was protected from the beating of the waves by several pine trees planted in front of it.
It is possible to state that the water of the Bay of Ancud and the surrounding zones is now 1.2 meters higher than before, which is clear evidence of the sinking of the zone following the earthquake. The observations conducive to this conclusion are the following:
(a) The water now covers the beaches and the low sector of the coast to a greater depth than the high tide did before the earthquake.
(b) Ships up to 25 tons now tie up at the sea wall in the sheltered part of the harbor when the tides permit; this was formerly impossible even at syzygy.
(c) The tides of the syzygies during July and August (the highest in 1960) reached the lower part of the town, especially in the vicinity of the Port.
Some other observations worthy of note are numerous small landslides around the Bay and changes in Estero Pudeto. The bar of the Estero is much less dangerous than before because the Estero is deeper and its mouth is wider. The lowlands of its banks are completely covered by water.
Punta Corona Lighthouse: The Punta Corona lighthouse is situated on the north coast of the Island of Chiloe, upon a hill 66 meters in height (figures 4 and 17).
Because of the earthquake the tower of the lighthouse fell and the chief of the lighthouse, Sr. Gabriel Jimenez, his family, and the rest of the personnel, were obliged to leave the vicinity of the buildings in case the antenna towers of the radio station should fall. Upon leaving the buildings they went westward down the hill so that they lost sight of Golfo Coronados and of the entrance of Canal Chacao, but they were able to see what happened in front of Playa Chauman (figure 18).
Between 8 and 10 minutes after the earthquake they noted that the sea had begun to withdraw slowly from the beach, leaving about 500 meters of the bottomuncovered. This process lasted about 10 minutes. Together with the withdrawal an enormous wave some 15 to 20 meters high was forming approximately 800 meters from the coast. In front of this wave smaller waves very similar to boiling water were observed (figure 19). The wave while forming gave the impression of being detained. This is certainly due to the fact that while the wave continued forming,it was impossible to appreciate the extent from the land. Soon this veritable wall of water advanced with great velocity and great force in the direction of the coast. It passed over the Isthmus of Yuste across Estero Chaular, sweeping away the part of peninsula Punta Larga de Chaular that closed the Estero on the southeast, then penetrated through the gap of Puerto Ingles, and continued through Golfo Ancud toward the sea. In its passage over the Isthmus of Yuste it washed away some houses that were there and all the small ships that it encountered in its passage (figure 20). The water had not totally retired when a second wave of lesser height formed in approximately the same place as the first, but it did not succeed in crossing over the Isthmus. Sr. Jimenez could not tell if a third wave was formed, but in any case he was able to establish that the sea maintained its abnormal conditions for several days. Subsequently he established that the present amplitude of the tide is much less than before the earthquake.
Generalities about the Zone of Chiloe: From the soundings and hydrographic reconnaissances made by Navy ships in the zone of Chiloe (figure 4) it may be stated that all the canals suffered alterations in depth as a consequence of the earthquakes, having been subjected to a general augmentation of depth caused by the general sinking experienced in the zone of the south of Chile.
It may be stated also that the tidal currents increased their velocities, especially in Canal Chacao, Paso Tautil, and the entrances to Quellon. A detailed description of the changes in the regime of the tides of this zone is found in Part IV.
Maullin: In 1laullin (figures 21 and 22) the maremoto occurred about 20 minutes after the earthquake. The first evidence was a withdrawal of the water followed by 8 sizable waves of which the second and the fourth were the highest. Their height was estimated at 14 meters. The waters penetrated deep into the interior and the waves were propagated upriver with great force, destroying all that they found in their path. The land has sunk; the town of Quenuir and the lower part of Maullinare now covered by the sea. In the map (figure 22) we were not able to indicate in detail the inundated zones because good data are lacking.
Caleta Mansa: The maremoto began in Caleta Mansa (figures 21 and 23) 15 minutes after the earthquake, in the form of a wave 8 meters high followed by twomore waves, at intervals of 10 and 15 minutes, of progressively greater height. The second wave had a height of approximately 10 meters and the third was estimated at 12 meters. After the phenomena had begun to decline, abnormal sea conditions continued for several days.
The waves had the greatest heights at the entrance to the bay and were describedas avalanches of water without breakers. The third wave passed over a warehouse whose highest point was 12.5 meters above the level of reduction of the soundings (the amplitude of the tide in Caleta Mansa is 1.8 meters).
In general the flooding experienced was scanty because the coast along the bay is steep. The extent of the inundation is indicated in figure 23.
At the time of the earthquake the motor ship ISABELLA had just begun to take on cargo, when the water began to rise because of the first wave. The cables were cut so that the ship could leave the port. The stevedores aboard the ship remainedaboard, while the others, on the dock and on land, ran with their families to nearby high places. Because of the rapidity with which this was done no lives were lost. The motor ship ISABELLA succeeded in leaving the Caleta after having been aground for some minutes because of the withdrawal of the water after the first wave.
One could observe from the hill up which the people had climbed that the waves penetrated inside the bay and then withdrew, tearing up and washing away the houses, trees, and 50 meters of access to the dock (figure 24).
During the withdrawal of the water, a great part of the bay was dry. The head of the dock, in 8 meters of water (referred to the level of reduction of the soundings),The following day, Caleta Mansa was sufficiently normal to permit the ISABELLA to enter and disembark the stevedores.
Later observations indicated that the head of the dock had resisted the pounding of the waves and the only destruction was 50 meters of the approach to the dock.
Vertical soundings made to verify possible changes showed that there were no variations in the depth of this bay.
Rio Bueno: In accordance with observations made by the A. P. Piloto Pardo, which made soundings in the Bay of Dehui and over the bar in Rio Bueno (figure 21),it was found that the bar suffered some important changes. Before the earthquake, the depth (referred to the level of reduction of the soundings), was 3 meters above the bar. This increased to a minimum depth of 5.75 meters after the phenomena. The bar, even though diminished, still presents a hazard because one can cross only under certain circumstances and with the aid of a pilot. The river itself did not suffer variation except that in general it was found to be deeper than before. With the increased depth over the bar there now exists the possibility that this river way may again be utilized by boats of adequate size as far as Trumao or perhaps even farther.
Corral y Rio Valdivia: The Bay and Port of Corral (figure 25) is the place from which we have the greatest amount of information, because three ships of the Merchant Marine were anchored in the port and suffered the terrifying effects of the maremoto. These ships were the CANELOS, CARLOS HAVERBECK, and SANTIAGO,the first two of which were lost. Information is also available from the people who observed the phenomena from land and in the reports from the maritime authorities.
The tidal wave was very complex because of the Rio Valdivia, which empties intoo the Bay of Corral. The information collected coincides in general and there areonly discrepancies in certain details. So that the descriptions of the effects will not be too confused, we will consider first a general narrative of the phenomena; second, that which happened as seen from the land; third, the adventures of the ships; and fourth, the changes in the Bay.
The earthquake, observed as a movement from the northwest to the southeast, was felt aboard the ships with great violence. The ships bucked and the masts and rigging swayed, giving the impression that they Were going to break. In the CANELOS a pile of sacks fell over. The movement was similar to a violent full speed astern at full power.
In the Port of Corral almost no destruction was caused by the earthquake. In the high part there were some cracks in the ground that caused more alarm than damage. On the other side of the Bay, in Niebla, there was more destruction, and a great landslide in the vicinity of Faro Niebla was observed and heard. There was great damage in the old Fort Niebla.
While the earthquake was going on, it was noticed that the sea began to bubble exactly as if the water were boiling. Then the ships began to bob about because of small horizontal movements of the water. Small whitecapped waves formed but did not break.
Some 10 minutes after the earthquake, Sr. Harold Weller, second pilot of the CANELOS, who found himself in charge of the ship, saw that the level of the sea was going down slowly. He estimated that it went down 1 meter or more in about 2 minutes. This movement, it appears, was noticed only by this official; nobody else mentioned it. The pilot asserted, however, that he had not been fooled because he could see quite clearly from where he was. A little later, about 1525, the Bay commenced to fill slowly, and currents of increasing strength began to form, constantly increasing in velocity also. All around the buoys whitecaps were formed by the velocity of the water. First to be submerged was the dock of a canning company located at Punta Laurel. A little later the water began to pass over the passenger dock. The first houses of the street between Corral and Amargos were washed from their foundations and collapsed, as were the first houses of the suburb of Corral Bajo (figure 25). The water continued to rise, inundating the first floors of the houses on Sixth of May Street, the principal street of the Port, located near the waterfront (figure 26). A school situated at the beginning of the road to Amargos was inundated to the eaves. In the first wave, the water reached a height estimated at 3 to 5 meters above sea level.
At approximately 1550 hours, the level of the water began to go down, first slowly and then with great rapidity. The outgoing water carried a great many houses and the ships CANELOS and CARLOS HAVERBECK Out to sea. Soon the beach of Corral began to dry and then the water withdrew some 30 meters horizontally from the fill of this Port.
At 1625 hours, a great mass of water entered the Bay in a gigantic wave that formed slowly in front of the Bay and was described as "A great wave of over-powering force that destroyed all that it encountered in its passage, such as docks, buildings of concrete and wood, and installations built of steel reinforcing such as the substation of the electric company and the Altos Hornos factory." (figures 27-29). The most exact estimation of the height reached by the water in this second or in the third wave, the other big one in Corral, is 8.5 meters, in spite of information that it produced damage at places up to 10 meters above the level of the sea. It is very difficult to establish whether the second or the third wave was the highest, since it appears probable that these waves were very similar in amplitude.
The inundation produced by the second wave held stationary for several minutesand then began to recede, slowly at first and then at a velocity approaching 15 to 20 knots. This withdrawal of the water carried away all of the settlement of Corral Bajo, part of Corral Alto, the lower parts of Niebla, and other settlements constructed on terranes less than 10 meters above the mean sea level.
Ships were carried away, pounded against the coast, and grounded, as will bedescribed in more detail later. While the water was retiring, a strange graben, or depression, in the water surface formed between Banco Tres Hermanas and Punta Piojo (figures 30-32). The phenomenonwas clearly seen from the CARLOS HAVERBECK, which was tied up over Banco Tres Hermanas, and from the hills of Corral. According to the description by the witnesses, it appeared that the water coming from the interior of the Bay and from the River fell into a ditch or trough some 6 to 8 meters deep and about 10 meters wide, emerging in a turbulent form on the other side and continuing seaward. Two tugboats tried to escape in the direction of the River butwere carried toward the trough. One of them, the PACIFICO, easily recognized by its white color, fell half astern and half abeam (figure 30) into the abyss, undergoing a double somersault before disappearing from view. Nothing more has been learned of this vessel; its remains have not been found. The owner of the PACIFICO was miraculously saved, without being able to explain how. His last memory before regaining consciousness about 0.75 mile away, on a beach on Isla Mancera, was the fall into the abyss while the boat was capsizing. The other tugboat, PUMA, was also drawn toward the trough, but its master, with more presence of mind and perhaps having better engines, succeeded in turning his tug. Steering into the abyss at top speed, he was able to cross it. His passage across the trough was almost simultaneous with the double capsizing of the PACIFICO. A little later, the third wave caught the PUMA and carried it upstream, leaving it in front of Isla _llancera. The owner saw a possibility of salvation and, by taking advantage of the currents, succeeded in reaching shelter in Rio Tornagaleones, arriving the next day in Valdivia.
Witnesses calculated that the trough remained for approximately 15 of the 20 minutes during which the removal of the water lasted. The lowering of the water was considerable, leaving a great part of the Bay practically dry. The water rose8.5 meters and it should have had a similar lowering, which would give an amplitude for a second or third wave of 17 meters. While the trough remained it was observed from the land that the water coming from the interior of the Bay and the River fell, forming a cascade 3 or 4 meters high on the west side of the Banco Tres Hermanas (figure 31), and that it was carrying millions of cubic meters of dirt and sand that had accumulated in the course of time. The changes produced by this and by the third wave, in the vicinity of the Bay of Corral, may be appreciated by comparison of the two maps, figures 33 and 34.
The third wave began to rise slowly, as the two others did, then sped up to 15 or 20 knots. The time this new wave began was not recorded, but its duration was estimated at 20 minutes. The water once again flooded a great zone, principally in Corral Bajo. It was observed to penetrate the farthest of the three, probably because the houses near the sea had been washed away and the water encountered less resistance in its advance. Some houses that had been washed toward the bay werereturned and piled grotesquely against the hillsides (figures 35-38). This advance also capsized the tugboat ORIENTE which was thrown over the blast furnaces of Corral, where it remained on its side when matters returned to normal (figure 39). All but one crew member escaped with their lives.
This was the last great wave. Many high waves continued for several days but were of gradually diminishing amplitude. When the water receded after the third wave there were no new phenomena noted in the Bay such as a recurrence of the trough at the side of Banco Tres Hermanas.
The destruction in Corral, as in the other ports of the Bay and the River, upstream as far as Valdivia, was extensive. The waves rose and fell along the River ravagingthe low zones of Valdivia (figure 40). There are no data concerning the distance from the mouth of the River to which the effects of the tidal wave were felt, but this certainly must have been considerable.3 The movement to which the ships anchored in the Bay of Corral at the time of the tidal wave were subjected, and also their tragic ends, merit meticulous description because they constitute a valuable experience and throw more light on the phenomena. Considering the complexity ofthe situation, it has been deemed best to give a detailed description of events, treating each ship independently.
At the moment of the earthquake the boats were in the following positions: SANTIAGO (figure 25) was tied tip at the muelle Frances (French dock) with twoanchors set, two lines fast to a buoy at the port bow, two lines to the land by the stern, and a line to a buoy at the starboard stern.
The CANELOS (figure 41) was tied to a buoy with three 1-inch cables and an 8-inch line and was further held by two anchors, the starboard with 7 panos4 of chain and the port with 5 panos of chain. The CARLOS HAVERBECK (figure 42) was anchored at the turn with two anchors, the starboard with 8 panos of chain and the port with 4 panos of chain, waiting for the tide so that she could fasten to a buoy, because she has just entered the port, at 1335 hours.
The first boat that suffered the effects of the tidal wave was the CARLOS HAVERBECK. When the wave appeared, it formed strong currents that began to drag the boat in the direction of Isla Mancera. As the current flow continually increased the crew let out 1.5 panes more chain. The motors ready from the instant the earthquakebegan, were set at full speed ahead. These measures, however, were not sufficient; the force of the current was too great. The capstans of the starboard anchor loosened, paying out the line, leaving the ship held by one anchor. The CARLOS HAVERBECK was dragged astern to position 3 (figure 42). A little later, the ship began drifting to port, toward the SANTIAGO, which was tied up at the French dock and trying to get loose. In spite of all the efforts to avoid collision, the CARLOS HAVERBECh scraped roughly against the side of the SANTIAGO. A small boat tied to the latter was totally destroyed, but served as a shock absorber in the collision. As the CARLOS HAVERBECK still had power, she arrived with the aid of her engines at position 5 in figure 42. There followed moments of currents and calms, which could not be detailed, thatcaused the ship to drift inside the Port. Suddenly, the CARLOS HAVERBECK was hurled over a buoy and, in spite of having stopped her engines, she tangled the cables of the buoy in her propeller and thus lost the use of her engines. While the ship remained between positions 6 and 7 it was noted that the French dock, to which the SANTIAGO was tied, fell over.
In taking advantage of a moment of relative calm, the CARLOS HAVERBECK tried to pass lines to the bows of the CANELOS which was at the time firmly maintaining her position. She called to the tug, PUMA, in the vicinity, which immediately responded, and requested her to carry the line to the CANELOS. The maneuver was about to begin when the first forceful withdrawal of the water took place. The CANELOS, because of the current, cut her cables and lines and at a velocity estimated at about 10 knots began moving seaward dragging her anchor chains. Following her, the CARLOS HAVERBECK was held by her port chain, about which she was turned, remaining with her bow in the direction of the Corral blast furnaces. As much chain as possible was paid out, but the brake of the capstan failed and the large chain ran out completely. At this point the CARLOS HAVERBECK was completely at the mercy of the tides and the current. The ship continued her vertiginous career toward the sea, passing very near the coast. Many houses were carried past her, some of which were between her and the coast. There was one moment in which the ship was stopped at Punta Laurel. It could not have been more than 2 minutes, but it was enough time for about eight stevedores to get ashore by jumping between the houses intercalated between the ship and the dry land. It was not possible for more men to do so because soon the boat was taken from this position and was run aground by the stern on Punta Chorocamayo.
The misfortunes suffered by the CARLOS HAVERBECK upon running aground were considerable. During the withdrawal, the ship remained aground at Punta Chorocanlayo. Not knowing what might happen, the crew began efforts on board to put some escape cables to the shore, but, unfortunately, there was not time for this. They began to feel the effects of the second wave, which floated the ship again and carried her, half sunk by the stern, toward the Banco Tres Hermanas, where she ran aground in position 12 (figure 42). In this point she resisted the returning waters, which were described by the captain as a "very rapid tide without breakers that ran into the bay." All around the ship great whirlpools were formed. She remained in this position about 20 minutes.
During a moment of calm, while the ship was aground on the Banco Tres Hermanas, a dozen stevedores, without any orders whatsoever, left in one of the lifeboats, which was suspended from a single davit, and reached the land after considerable effort.
The other lifeboat was also launched carrying 22 persons but as soon as the boat had left the ship the current began running seaward. The boat returned to the side and the crew boarded the CARLOS HAVERBECK again, with the exception of three men: the third mate, a sailor, and a boatman. Of these, the last two disappeared and nothing more is known. The third mate, Sr. Eduardo Soto Ulloa, who was in charge of the embarkation, was miraculously saved. He told the following extraordinary history to his colleague, the first mate, Sr. Carlos Hartmann Orostegui.
No sooner was the lifeboat in the water than it was totally broken up by the strong current. The water had now receded sufficiently around the CARLOS HAVERBECK that one could walk on the bottom. He had hoped to get to the propeller and take hold of it in order to avoid being dragged away. He did not succeed in this objective because the current was too strong, but he saw that the blades of the propeller were doubled and the chain of the buoy still tangled in them. The out-going current then carried him away toward the open sea. His memories are not very clear. He was struck several times in different parts of the body. The life preserver that he had put on saved him from being drowned. One time in the middle of the Bay he found a boat into which he climbed; a little while later the boat capsized and he fell into the water again. A strong current, probably the third wave, dragged him inland. He remembers that he succeeded in grabbing a spar and then lost consciousness. He came to at a place in Rio Valdivia called Cancahual, approximately 4 miles from the mouth, where he was rescued at about 2000 hours by the inhabitants. He suffered a fractured skull and one or two broken ribs. He
remained in Cancahual from Sunday until Friday, when he was taken to Valdivia, there to receive his first medical attention since his adventure.
When the water withdrew after the second wave, the CARLOS HAVERBECK was grounded and then dragged to the north over Banco Tres Hermanas, running aground in position 13. From this point they were able to observe clearly the trough that formed and that the Bay was for a while practically dry. The current was very rapid and an accumulation of sand formed by the starboard side that contributed even more to the pronounced list of the ship (figure 32). The third wave dragged the ship, still over Banco Tres Hermanas, to position 14. While this was going on, the steamship SANTIAGO was seen going seaward on one side of the Bay; simultaneously on the other side, near Niebla, entering with great velocity and very steeply listed, the steamboat CANELOS was observed passing over the rocks and the breakwater that had been at the outlet of the Rio Valdivia. When the water went out this time the CARLOS HAVERBECK was dragged away once more, finally running permanently aground in position 15 (figure 42-44).time. The maneuver s difficult, long, and risky, but they were able to land all the crew (figure 45). At 2242 hours, when only the captain and seven officers remained aboard, the boat drew near the ship for its last load. A strong current developed that destroyed the boat against the side of the CARLOS H VERBECK; the men in the little boat, however, succeeded in saving themselves. The list of the CARLOS HAVERBECK continued to increase until the water reached the boat deck.With great effort they succeeded in launching a raft and finally abandoned the ship at 2300 hours, at which time it had an approximate G0-degree list.
The raft was first swept to Isla Mancera (figure 46), but the men were not able to gain the coast of the island nor that of Corral. After that, the raft was washed, now toward the interior, then toward the open sea, until a stronger current carried them to the north. They passed within 200 meters of the SANTIAGO, which was now safe at anchor; they made luminous signals and shouted to her but the SANTIAGO was unable to give them aid. The current continued carrying them seaward until they were in front of Morro Gonzalo, where the current changed directions. Finally, they were left stranded on a beach to the south of Caleta San Carlos. Once ashore, around 0130 hours on 23 May, they climbed the cliff to a house where they spent the rest of the night. Near this house, on a plain about 25 meters above the level of the sea, they found the remains of houses and other objects that had been thrown to this height by the waves of the maremoto.
On their return by land to Corral, passing near Caleta Amargos, they saw in acanyon located behind a eucalyptus forest the mooring barge from Puerto Corral and the second story of a hotel from Amargos.
The other boat that was lost in the maremoto was, as has been said, the CANELOS, the property of the firm Haverbeck and Skalweit. The CANELOS survived the influx of the first wave, but when it receded the cables with which she was tied up to thebuoy parted and she was carried outward, passing near the coast with anchors dragging (figure 41). When the earthquake occurred, the order was given to ready the motors, and the ship was thus able to help herself with them in the first phase. Another precaution that had been taken was to disembark all the stevedores as soon as the earthquake occurred. While in position 2 she was able, with the aid of her engines and anchors, to resist sufficiently well even though she lay athwart the advance of the waters and listed dangerously.When the harbor began emptying rapidly, the boat was dragged to position 4. It has been calculated that it took only 10 minutes to run this distance of 1.5 miles. At this point many currents and waves were encountered that carried them now to e north, then more to the south. As the ship still had the use of her engines, the crew members hoped to be able to leave the Bay, so they began to weigh the anchors. While they were doing so, the outward current increased and the ship was left high and dry. The withdrawal was so rapid that they failed to stop the capstan and engines before they found themselves aground, so the propeller began to lift mud and sand from the bottom. This covered the intake of the condenser, leaving them momentarily without motors. From the CANELOS, it was seen that the anchor chains were stretched across the almost dry Bay of Corral. The center of the Bay now looked like a river whose water ran with great velocity seaward.
The pilot, Sr. Weller, said that at this time they looked toward the horizon and saw a wave whose height he estimated at 8 to 9 meters breaking and advancing with great velocity. Very soon this wave, the third, arrived at the ship carried her off listing more than 45 degrees. Part of the wave broke over the deck, leaving it full of sand, small stones, and fish. The wave washed the C ANELOS away at about 20 knots toward the interior of the Bay and very near the coast of N iebla, with the bow toward the south. While the CANELOS was entering the Bay near Niebla, the SANTIAGO was leaving by the side of the Bay near Corral. The CANELOS passed, listing sharply, about 150 meters from the lighthouse at Niebla and was dragged over rocks that destroyed the keel. The crew saw that the boat was losing fuel. Shortly after arriving opposite the sea wall of Niebla, which had suffered grave damage from the first two waves, the ship turned (perhaps because the anchor that she was still dragging had caught and held for some m inutes) and swung sidewise, grounding herself for 10 minutes on Banco Simon Rey, position 5 (figure 41). Here the crew noticed the currents that were running in Rio Valdivia: by the bank at Niebla, the water was lowering with great velocity, and a strong current was going up the opposite bank. It was this current that floated the C ANELOS anew and carried her 1.5 miles upriver, finally leaving her permanently aground at position 6 (figure 47). The crew therefore abandoned the CANELOS at 1800 hours, because they feared she would overturn. The list was constantly being augmented by the accumulation of sediments along one side, and undermining of the river bed on the other side of the ship took place each time the current went out.
As has been mentioned, the steamship SANTIAGO was tied up at the French dock at the time of the earthquake (figure 48). A little while after the collision with the CARLOS HAVERBECK, the dock fell over and the lines were cut. The S NTIAGO floated off, passing over the fallen dock to position 2, where she withstood the first outflow with the aid of her anchors and motors. During the second wave, she managed to stay inside the port, although she was carried from position 2 to position 3, very near a tank constructed on some rocks in front of Sixth of May Street. From the ship it could be seen that a gigantic wave was inundating the Port of Corral and causing tremendous destruction there. The SANTIAGO became surrounded by the houses of Corral that were being carried away toward the open sea. Here the ship was passed very closely by the house of the Captain of the Port and the firehouse barracks, among others. The man in charge of the firehouse was ringing the bell. This man, when he realized that there was going to be a maremoto, climbed to the tower of the firehouse and, thinking it would he most effective to call the attention of the people with the bell, began ringing the bell loudly. He was doing this when the house was carried away by the water and, according to witnesses, continuedringing the bell even though he was in the middle of the Bay. Later this valiant cuartelero succeeded in getting to land, thus saving his life.
The SANTIAGO survived the third wave, but upon the withdrawal of the water following the third wave, she was dragged rapidly seaward with her bow to the south. The SANTIAGO left the Bay by a sort of canal that had been formed between the coast and Banco Tres Hermanas, at the same time that the CANELOS, on the other side of the Bay, was being carried upstream. Currents which had formed in the Bay dragged her from position 5 to 6, from where she soon drifted in the direction of Ensenada San Juan. With the withdrawal of the waters the ship was again swept seaward, her anchors dragging (they had not been cut loose, although the chains had been filed), to a spot in front of Ensenada Molino (position 9, figure 48). Fromthe SANTIAGO some houses and, later, the raft with the officers of the CARLOS HAVERBECK were seen passing, but, because of the currents and waves, the SANTIAGOs crew were not able to help them. The SANTIAGO spent the night in this position. The next day they weighted anchor to search the zone in front of the harbor to see if the could rescue anyone. They then received instructions from the Direction del Litoral to return to Valparaiso. However, although the SANTIAGO had succeeded in saving herself from the maremoto in Corral, she never arrived at Valparaiso. Instead she ran ashore on a point of Isla Mocha because abnormal currents caused by the tidal wave caused an error in navigation. Her radar had been inoperative and could not be repaired before the maremoto. The SANTIAGO was totally lost.
The changes observed in the Bay of Corral and Rio Valdivia as a result of the earthquake and the tidal wave are extraordinary. It is sufficient to compare figure 33 to figure 34 to appreciate the changes in depth. In the rest of the Bay the changeswere similar. In front of the Bay, i.e., in the outer part, the phenomena are the opposite. There are zones in which the depth has diminished as much as 6 meters: for example, where the depth had been 32 meters it is now 26 meters. This is due to the fact that the waves swept the interior of the Bay and deposited the sediment on the exterior. When a complete new mapping of the Bay has been made it will be possible to calculate the amount of material transported.
Banco Tres Hermanas no longer exists. Over its former location there is now a sounding of 5 or more meters of water. In other places where there had been 2 to 3 meters before the tidal wave there is now 7 to 9 meters.
Rio Valdivia has also undergone increases in depth and is now navigable for boats of average tonnage. In addition to the increases in depth caused by the tidal wave,there was a sinking of the land estimated at 1.5 meters in Corral and Valdivia. As a consequence, Rio Valdivia was widened in the zones where its banks were low.
Mehuin: The first evidence of the tidal wave in Mehuin (figure 21 and 49) was a rapid withdrawal of the water from Rio Mehuin o Lingue. Fifteen or 20 minutes after the earthquake, a great, rapid increase in river level began. Then an enormous mass of water washed away the houses at the mouth of the river and began to wash away the first houses on the Bay shores. The formation of the waves, three in all, was observed to take place about 3000 meters from the coast. The highest wave was the third, estimated at 8.5 meters of height.
The Alcalde de Mar of MIehuin said in his report "Those of us who were on the south bank of Rio Lingue climbed the hills, from whence we observed the tragedy of the fishermen, who were fleeing through the brush with their women and children,falling and getting up again. Some of them were reached by the waves. Those who saved themselves took refuge on a little sand hill about a kilometer from the bay, others on a knoll at the mouth of the river, that subsequently remained isolated."
The building of the Marine Biology Station of the Universidad Austral de Valdivia was carried off by the first wave, washed seaward, and destroyed upon the cliffs of the coast.
As a consequence of the earthquake and the tidal wave there are notable changes in the river. A bar formerly made passage difficult for even the smallest boats, limiting usage to a maximum of 6 tons. Now the river can easily be crossed by large boats because the depth over the bar has increased. Furthermore, there was a straightening of the river, and several changes were made in its course. As in all theaffected zone, a sinking of the terrane occurred, calculated to be about 1.5 meters (figure 50 and 51).
Queule: A little to the north of Mehuin is Caleta Queule (figure 21 and 52). No data have been obtained about the maremoto here, because the Alcalde de Mar of Queule died as a result of this phenomenon. The transformations suffered by the river were obtained through the kindness of the Alcalde de Mar of Mehuin, and the description of the consequences of the earthquake and tidal waves have been obtained from the work of Veischet (p. 19) :
"Not a single house remained intact, and their remains are encountered as much as 2 kilometers toward the interior, together with the remains of fishing boats and uprooted trees disseminated in the muddy forest or over a meadow at the foot of the coastal cordillera. The breaker that passed over the village reached a height 4 meters on its arrival at the first houses, mute witnesses of this fact are the pieces offloating wood that have remained entangled in a group of trees. These trees supporting one another were not doubled by the waves. It is accurate to consider that the great wave had passed over the shore ridge and had travelled, before arriving at the houses, a distance of 1.5 kilometers toward the interior."
"The river augmented its width, the inter-tidal zone reached to the western bank of the old village and the work of the tides has converted the estero, formerly a meander, into a small estuary" (figure 53-56). The bay also suffered some changes which were described as follows: "The bar of the Caleta [bay] was opened into a canal 5 meters deep bordering the coast. The former bank of the mouth of the Rio Queule has disappeared."
Puerto Saavvedra: The most noteworthy physiographic feature of the Puerto Saavedra area (figure 21 and 57) is the offshore sand bar that encases a large stretch of the Rio Imperial and separates it from the sea next to the coastline. The earthquake did not produce much damage in Puerto Saavedra, but the tidal wave destroyed it almost completely.
The first evidence of the tidal wave was a great withdrawal of the waters that augmented the current of the river, 25 to 30 minutes after the earthquake. A little later the first wave, 3 or 4 meters in height, reached the coast and carried away part of the offshore bar. The third wave was the biggest of all; its height has been calculated at 7 to 8 meters. It totally destroyed the village. It penetrated to the interior as far as the mouth of the Rio Imperial and opened a new mouth across the offshore bar. According to information received, several other high waves came during the night. One inhabitant of Puerto Saavedra, whose house had been protected by a pine forest, spent the night on the roof while the zone around him was inundatedrepeatedly. The remains of many houses were encountered 2 and 3 kilometers inland. A newspaperman described what he saw in Puerto Saavedra as follows: "Now the only indications of its extinguished existence are some roofs upon the soil and hundreds of tablets that served as the walls of the fragile houses of the villagers. Only the cracked walls of the church and the principal buildings that surround it remain standing, along with the local school.
"The tiny settlement, Nehuente, situated on the other side of the Rio Imperial, disappeared completely. There is not remaining a single wall to indicate its existence.
"Trovelhue, at more or less 40 kilometers, was submerged in the river water, but upon the retiring of the water its inhabitants returned to their houses.
"Between Trovelhue and Puerto Saavedra the landscape is completely altered because the river changed its course, carrying away a great amount of beach and terra firma."
Among the houses still standing, mentioned by the newspaperman, one house in Puerto Saavedra that was not destroyed should be pointed out. It belongs to Sr. Pablo Lifer and is north of the village near the mouth of the Rio Imperial. The report of Watanabe and Karzulovic (p. 49) says in this respect: "This is in a higher terrain than the rest of the town and has a bunch of trees between it and the banks of Rio Imperial. It is evident that this row of trees, even though it is very small, diminished in notable form the force of the tidal wave, protecting the houses from certain destruction. In this same house the sea reached an altitude of about 60 centimeters over the foundations. In the other houses the sea rose to a level of several meters." According to Weischet, the Rio Imperial now empties through the mouth opened across the offshore bar. The width of the mouth is now about 1,000 meters. "The rest of the littoral barrier is now an island, which in its extreme north doubles against the south bank of the In perial River. It now seems that Puerto Saavedra is separated from the river and its actual location is on the side of a lagoon that has a very narrow and shallow exit. If this situation continues, the entrance to the bay will be filled by beach sediments and this ancient port will be separated from the sea."
The new mouth of Rio Imperial was investigated by the Navy corvette Casma and described as follows:
"The coast in front of Rio Imperial from MIorro Cauten to the south of the old mouth from about a mile of the coast was investigated; it was obviously unapproachable over its whole length, with strong breakers that impeded the approach of any small boat. Great landslides were seen in the hills from Cauten southward, with slides that practically divided the hills in two and at times with tremendous fractures oriented north-south.
"As a consequence of the earthquakes and tsunamis, the sand bar that exists between the conjunction of Rio Macul and Rio Imperial toward the south has been opened for a thousand meters.
"The offshore bar, or littoral ridge, referred to before is a tongue of earth and dune sand some 500 meters in width and 10 to 15 meters high. Before the earthquake, in the place at which the bar was broken, Rio Imperial overflowed to the sea in winter by a tiny riverlet.
"The mouth now presents steep banks of sand and earth about 10 meters high, and breakers 3 to 5 meters high now totally occlude the entrance. The conditions that they could observe in the new mouth were completely adverse to the use of a small boat."
As in all the affected zone, Puerto Saavedra suffered a general sinking of 1.2 meters.
Isla Mocha: On Isla Mocha (fig. 21 and 58) the earthquake was felt with great intensity and great landslides occurred that swept away everything in their paths, such as trees, animals, etc.
At some places, cracks were produced in the ground.
The sea wave began about 10 minutes after the earthquake, the first evidence being a withdrawal of the water from 100 to 200 meters. Then came three waves that approached the island from the southwest, affecting the south and west coasts with greatest intensity.
The first wave was highest and reached an estimated height of 15 meters. The houses of the inhabitants, as well as the buildings of the lighthouse, dock, etc., located in Caleta la Hacienda, were totally erased.
The island and adjacent zones were uplifted an estimated 1.7 meters. This may be demonstrated by rocks that now crop out of the sea, as well as by soundings made inside the 10-meter level, by which it was proved that they are now 2 meters less.
Lebu: The phenomena in the port of Lebu (fig. 21 and 59) were completely different from those in the zones farther south. In this port, the most important seismic movement was that of 21 May at 0605 hours. During this earthquake, the land was uplifted about 1 meter. According to the Captain of the Port the following evidence exists :
1. An uplifting of the river bed and adjoining banks was noted. The river was left without flow except in the middle, while the banks and docks remain dry at low tide and with a depth of only about 1 meter at high tide. This makes navigation by tugboats and cargo barges in Rio Lebu quite impossible.
2. The bar at the river mouth was displaced by an uplift of the land that formed new embankments of sand and sediments that have made navigation of tugs with drafts afts in excess of 1 meter even more difficult at low tide.
3. Coal may be loaded from the Errazuriz dock of the Victoria Coal Company only at high tide.
4. Rocks that surround the shallow places in the port are now exposed to view.
5. El Guape, a stony island that serves to break the ground swell, formerly disappeared during high tide. Now it is seen as a pinnacle that the high tide covers only by half.
The tidal wave of 22 May affected the port of Lebu but elapsed time between the earthquake and the maremoto was not recorded. Three waves arrived at the coast Whose maximum heights were estimated at 3 to 4 meters. The waves were felt as far as 5 km up the river.
Lota: The Captain of the Port of Lota (fig. 21 and 60), with the pilot of Lota, observed the phenomena that affected this port from the Fiscal dock.
First, strong breakers formed at Punta Escoria. At 1600 hours the sea withdrewabout 150 meters horizontally. A little later the first wave arrived. This reached points about 20 meters farther inland than the tides of the syzygies. This phenomenon was repeated five times, the last advance being at 0200 hours on 23 May. The abnormality of wave conditions continued decreasing until 27 May.
The vertical height of the waves was 1.5 meters over the average level of the sea.
Isla Juan Fernandez: The first alterations of the sea in Bahia Cumberland (fig. 61, Isla Mas a Tierra of the Archipelago of Juan Fernandez) occurred while the majority of the inhabitants were on the dock or nearby, observing the arrival of the sailboat ROBINSON CRUSOE that was coming from Valparaiso.
The sea slowly withdrew about 30 meters horizontally, producing great consternation among those present. Precautions were immediately taken to save the smaller ships at their moorings. Six to eight waves followed whose altitudes were not estimateds but which caused no damage except to carry away some boats that were later retrieved.
There is no information as to what happened on the other side of the island because that coast is completely uninhabited and very difficult to reach. The coast was certainly affected because it lay athwart the advance of the waves.
Issla de Pascna (Easter Island): The population of Isla de Pascua (fig. 62) is concentrated at Hanga Roa, on the west side of the island, hence there were no witnesses to the maremoto, which affected only the coast that faces the South American continent. The Military Chief of the Island estimated the height of the waves at about 6 meters. There is evidence that the sea penetrated the lower parts of the islands to 500 meters, probably aided by a strong wind that was blowing that day.
In addition to destroying some windmills used to pump water for animals and some stone fences, it destroyed the Ahu of Tongariki. Ahus are platforms of stone upon which in the past the islanders erected statues of stone, which later were thrown down, remaining in the near vicinity.
The Rev. Padre Sebastian Englert, who visited the site, described what he saw as follows (Englert, 1961) : "I saw with surprise what may be described only by thegraphical expression that 「no stone remained upon stone!」 An enormous avalanche of water, probably reaching some 6 meters over the level of the sea, invaded the coast of Hotuiti for a distance of 500 meters and swept away the ahu, statues, sun-shades, fences, and blocks of stone with such force that only a person who had known the ahu well before its disappearance could now establish its former location.
"The waves of the sea appear to have played with the heavy statues as if they were balls. They remain scattered around 50 to 150 meters from the site of the ancient ahu. I was especially taken by one of these and was struck by its beauty. Even though, some years before, it fell my lot to inventory all the statues of the island and to put numbers on them, I had not appreciated the state of sculptural perfection because the head and chest had been partly buried. Now it lay stretched out mouth upward among stones and rubble some 100 meters from its former location. As it measured 6 meters in length by 3 meters in width at the widest part of the trunk, from arm to arm, it was possible to calculate that it weighs at least 20 metric tons. The waves of the sea transported it with an irresistible, but at the same time such gentle, force that it had not deteriorated nor fractured, and the perfect form of the face and chest causes admiration."
PART III. PORTS OF TALCAHUANO AND POINTS NORTH
From Talcahuano to the north, records of tide gages are available from which the exact times, amplitudes, durations, and forms of the waves and the total time during which abnormal sea conditions prevailed may be obtained. Copies of the marigrams obtained are included in this report as figure 1, jj-rr, in rear pocket.
The most notable thing from Valparaiso northward was that the waves of greatest amplitude did not occur on 22 May as one might suspect, but on 24 May. One explanation might be the influence of new earthquakes that occurred in this same zone
The waves had different amplitudes in different ports, clearly showing the influence of submarine topography.
In Talcahuano the waves reached the greatest height, about 3 meters above mean sea level. The water did no damage except for inundation.
One noticeable thing is that, contrary to the observations made more to the south, the first movement in all these ports was an elevation of the water.
We include in table 1 the data for the several ports, beginning at the time the effects were first felt. The position of each of these ports is indicated in figure 63.
PART IV. ABNORMALITIES OF THE TIDES OF CHILOE AND LLANQUIHUE IN
The interior maritime zone between Chiloe and Llanquihue, bathed by the Golfo Ancud, Golfo Corcovado, and Seno Reloncavi, is characterized by the great tidal amplitudes measured in its ports. These amplitudes vary between 5 and 7.4 meters. These great ranges, when compared with those.of Chilean ports bathed directly by the Pacific Ocean where the amplitude fluctuates between 1.6 and 2.0 meters, show the great difference in this important oceanographic factor between the two zones.
The great amplitude of the tides has given to the interior ports of Llanquihue and Chiloe a special character, which has been used to advantage economically, industrially, and artistically by the inhabitants of the zone.
Before the earthquakes, the tides were not abnormal, and the high tides of the syzygy, those tides at the days of new and full moon, did not seem extraordinary, to the coastal population.
For example, in Quellon (figure 4, 7, 8, and 13), a port situated on the south of Isla Grande de Chiloe, the highest tides of the year (those that occur at the double coincidence of syzygy with the moon in perigee) reach a fraction of a meter over the high tides of the month. This phenomenon formerly escaped notice because the water never passed above the level of the sea wall; on the dock situated to the west of the bay, whose platform is almost at a level with the wall, the water formerly rose only one or two rungs more up the access ladder to the platform, without attracting the attention of the occupants. Thus the highest tides had never before occasioned problems for the population.
Following the earthquakes of May, 1960, the panorama changed.
The tides of the first week of July and of August completely covered the sea wall and inundated the Avenue. This same phenomenon occurred in Queilen, Chonchi, Castro, etc.
The question arises, what happened to Chiloe? The only response is that the insular platform has subsided because of the violent earthquake of May. A good approximation of the amount the insular platform has settled may be obtained in Quellon; the freeboard of the dock was 1.5 meters and the water rose 0.71 meters above the dock; hence, the sinking of the bottom in Quellon is about 2.21 meters. The sinking of the insular platform, different in different places, is a definite fact in the zone of Chiloe; on the other hand, in such ports of the continent as Chaiten, Ayacara, etc., this phenomenon did not cause alarm and the sinking was less.
This alteration of the depth of the sea, a disaster for the population, was of benefit to the ports; because of the increased depth the ships now have a greater maneuvering area.
In the last week of July 1960 the B. A. PILOTO PARDO departed on an 18-day cruise, making tidal observations in various ports of the interior of Chiloe. Thirty-three localities were visited, from Tenaun in the north to Melinka in the south, returning by the continental ports and adjacent islands.
The effects produced by the high tides were very noticeable. Coastal towns were flooded, and roads and trails at the edge of the beach, passable even during the highest tides before the earthquake, had now disappeared. In the middle of the patio of the school at Ahoni, for example, the new line of the high tides may be seen clearly traced by a line of algae, scraps, and shavings. In all the localities of the island the high tide line is now between 10 and 15 meters farther inland than before.
In Quellon, the port most affected by the high tides, observations were made between 4 and 7 August with a tide scale located in the dock, then undergoing repairs. The platform of the dock coincided with the 6.00-meter mark on the tide scale.
Observations were begun at 1000 hours when a tidal altitude of 6.02 meters covered the dock totally. The Port Construction official, in charge of repairs, averred thatthe dock was constructed so that, formerly, during the highest tides it had had 1.5 meters of freeboard. Now, lacking 3 days before the highest tide, the dock was already inundated. The day-to-day observations registered an increase in tide scale reading as is indicated by the table below.
In the port of Queilen (fig. 4 and 64-66), where the same phenomena occurred, the inhabitants were saved from an inundation by the happy chance that a householder had constructed a second dike a little higher than the sea wall and at a short distance from the bases of the houses.
The photographs give various aspects of the port of Queilen on 7 August 1960, the highest tide of the year.
REGIMEN OF THE TIDES OF CHILOE
The tide tables of 1960 show that Puerto Montt is the master port, or port of reference, for the zone of Chiloe. The secondary ports Quellon and Queilen are shown below to have a positive time difference with respect to Puerto Montt, i.e., the times of high and low tides in Quellon and Queilen occur 15 and 30 minutesrespectively, after those in Puerto llontt. On 7 August 1960 the hour of high tide in Quellon, according to the tide tables, would have been as follows:
Time of high tide, Puerto Montt ......................................... 1351
Time of high tide, Quelldn ............................................... 1406
Difference, min ........................................................... 15
and in Queilen :
Time of high tide, Puerto llontt ......................................... 1351
Time of high tide, Queilen ............................................... 1421
Difference, min .......................................................... 30
The observations made after the earthquake, during August, 1960, showed this sequence to have been altered, as may be seen by comparing once again the hours of high tide at Puerto ".\Iontt with those at Quellon and Queilen.
Before the earthquake the high tide occurred in Quelldn 15 minutes after it occurred in Puerto Montt-after the earthquake the high tide occurred 50.3 minutes, on the average, before it occured in Puerto ~tontt.
The following compares high tide times of Puerto ~Iontt and Queilen on 7 August 1960:
Time of high tide, Puerto Montt ......................................... 1400
Time of high tide, Queilen ............................................... 1303
Difference, min .......................................................... - 30
Before the earthquake the Queilen high tide came 30 minutes after that in Puerto Montt; now it happens 30 minutes before.
In this calculation the time of high tide in Puerto \1ontt has been obtained directly from the portable tide gage located provisionally at Angelmd in Puerto Montt, and the hours of the secondary ports have been taken from observations made with the tide scale in both ports. Although the period of observation is relatively short it may be seen that the times of the tides in this zone have been affected by the earthquakes.
An examination of the map of Chiloe gives us a probable explanation of this change of time. With the descent of the insular or maritime platform, the mass of water in the zone between Corral and Guafo has been increased. The velocity of a tide varies as a function of depth in accordance with the formula V = (pg)^(1/2) , where p is the depth and g the acceleration of gravity; hence, velocity is greater in deeper waters. It is perfectly reasonable to suppose that the velocity of translation of the tide wave has undergone an augmentation along the west coast of Isla Grande de Chiloe, as the tide runs through this zone without being opposed by geological obstacles until arriving by Boca del Guafo. On the other hand, the branch of the current that bifurcates near Chacao takes longer to get to Puerto Montt, because it has to cross shallows and make its way past the topographic accidents of Seno Reloncavi.
In order to verify this alteration in time, we can make a comparison of the interval between the tide and the passage of the moon (Establishment of the Port at Quellon before and after the earthquake).
Along the beaches of Chiloe, the Establishment of the Port increases from north to south; for this reason we affirm that the wave of advance of the tide has this direction.
We see that the value increases to 12 hours 25 minutes, from whence it returns to zero, because the moon, the body to which the tide-moon interval is referred, has in this lapse passed from the upper to the lower meridian. This interval is known as the semidiurnal lunar period.
To obtain a reliable value of the Establishment of the Port, we examined the Hydrographic Archives and found some tidal observations on three consecutive days, 18-20 November 1938, made by the cutter YELCHO at Quellon :
From a comparison of the tide-moon interval the difference in the time of tides at the master port and the secondary port may be obtained. This value is given in Part II of the Tide Tables.
According to this, high tide occurs first in Quellon and 48.3 minutes later in Puerto llontt. Comparing earlier the hours of high tide in both ports a result of 50.3 minutes was obtained: both results are quite comparable.
1. The regimen of the time of the tides has been changed in the interior ports of Chiloe.
2. The insular platform on the interior coast of Chiloe has descended and the depth of the ports has increased.
3. The schedule of tides in Puerto Montt has not changed.
From these conclusions we may expect that future hydrographic work done in Castro, Quellon, Queilen, etc., will show variations with the hydrographic data obtained before the earthquake, including changes in bathymetry, tidal phenomena, and the details of the coastline.
This paper details the efforts of the Chilean Navy in warning of the tidal waves that followed the earthquakes of May 1960 and the efforts made to collect information concerning the tsunami. Details of time of arrival, damages, wave height and run up are presented for almost all ports in the affected area beginning at Puerto Aysen and working northward. Changes in water depth, caused by erosion, deposition, and changes in land elevation are reported.
The fates of several ships caught in the great waves are described in detail. Marigrams of the tsunami are given for all available Chilean ports.
The times of high and low tides in the Gulf of Chiloe changed following the earthquakes.
The cooperation of the different maritime authorities, captains and pilots of merchant ships, chiefs of lighthouses, and observers at the tidal stations is sincerely appreciated. The authors also wish to thank Dr. Wolfgang Weischet, Director of the Institute of Geography of the U niversidad Austral de Chile, for the information and photographs supplied by him, and Sr. Oscar Arriagada, graphic reporter of the newspaper "El Mercuro," of Valparaiso, for the photographs of Corral and Valdivia.
Department of Navigation and Hydrography, Chilean Navy Information Bulletin No. 56
Ano YVI. Englert, Sebastian
1961. "Novedades Arqueologicas de Isla de Pascua," ("Archeological Novelties of Easter Island"), Rev Marina, No. 5, Vol. 76.
1960. "El Maremoto del22 de Mayo de 1960," ("The Tsunami of 22 May, 1960"), Rev Marina, No. 5, Vol. 76.
Watanabe, Takeo, and Juan Karzulovic
1960. Los Movim.ientos Sismicos del Mes de Mayo de 1960 en Chile, (Seismological ]Iovements of the Month of May, 1960, in Chile), University of Chile, Institute of Geology Publ. No. 14.
1960. Contribuciones at Estudio de las Transformaaciones Geogrdficas en la Parte Septentrional del Sur. de Chile pot, efecto (let Sisnio del 22 de May de 1960, (Contributions to the Study of the Geographical Transformations in the Northern Part of the South of Chile for the effects of the Earthquake of 22 May, 1960). University of Chile, Institute of Geology Pub]. No. 15.