Lake Nahuel Huapi and its 1960 Tsunami

Few people know that Lake Nahuel Huapi experienced a freshwater tsunami in 1960. This is an extremely rare phenomenon, and it had some nasty consequences on the coastline and the city and port of San Carlos de Bariloche.

Valdivia earthquake of 1960

The "1960 Valdivia Earthquake" or "Great Chilean Earthquake" was the largest earthquake ever recorded: its magnitude was 9.5 to 9.6.

It took place on May 22, 1960, and killed between 1000 and 6000 people, and provoked tsunamis that rushed across the Pacific Ocean and struck New Zealand, Australia, Hawaii, the Aleutian Islands and Northwestern Asia. The tsunami also battered the coast of Chile, and the tremor caused a tsunami in Lake Nahuel Huapi.

The Lake Tsunami

Those on the lake's shores saw the water recede from the beaches and return as a wave front that was 5 m (16 ft.) high. It razed the local port and killed two people.

A paper published in 2009 analyzed the lake tsunami, and why the port was razed (Villarosa, G., Outes, V. ., Gomez, E. A., Chapron, E., & Ariztegui, D. . (2009). Origen del tsunami de mayo de 1960 en el lago Nahuel Huapi, Patagonia: aplicación de técnicas batimétricas y sísmicas de alta resolución. Revista De La Asociación Geológica Argentina, 65(3), 593-597. Retrieved from https://revista.geologica.org.ar/raga/article/view/891).

The authors concluded, after analyzing the lake bed by the port, that "The impact of the seismic waves produced huge mass-failure below 70-80 m water depth. Thefailure was probably induced by the presence of a non-cohesive surface (tephra layer?) that acted as a sliding surface, and the mobilized material evolved into a mega turbidite in the deep basin. A large volume of water was displaced by the mobilization ofthese sediments producing a tsunami that hit the coasts of Bariloche and destroyed the harbor of the city."

It was a period of activity along the edge of the tectonic plates in Southern South America, the Nazca Plate subducts beneath the South American Plate and provokes earthquakes and volcanic activity along a line running beneath the Andes. The first quake shook Concepción (Chile) on May 21st. with an 8.1 magnitude. The next day two new quakes (7.8 and 7.1 magnitude) hit Concepción again, followed by the record-breaking 9.5 quake of Valdivia. It triggered the eruption of the Puyehue-Cordón Caulle volcano on May 24th which spewed ashes on Lake Nahuel Huapi and the City of Bariloche. Below is a view of the eruption.

Puyehue-Caulle erupting in 1960 seen from Bariloche.

Bariloche Port

The port of San Carlos was originally built in the 1930s and consisted of a timber pier (Pictured below in 1937).

San Carlos port, Bariloche, 1937

The port was enlarged with an enclosure along its northern side as can be seen in the picture below from the early 1950s.

San Carlos port, 1950s

It was damaged by a fire in 1958 and rebuilt. Then the tsunami destroyed it. Below are some pictures taken after the tsunami. Some ships in the port survived, others sank.

The tourist ships that visited Victoria Island, Puerto Blest and the Arrayán forest on Quetrihue Peninsula, moved their operations to the port of Llao Llao, Puerto Pañuelo port. It took decades for a new port to be built on the site of the old one. The port modern can be seen below.

There have been other tsunamis in the past

Geologic sampling of the sediments in the lakes Moreno, El Trébol, and Escondido, on the southern side of Lake Nahuel Huapi, (see the Thesis - Eventos paleoambientales en la cuenca del Lago Nahuel Huapi registrados en testigos sedimentarios lacustres durante los últimos 19.000 años, Lirio, Juan Manuel) found that the Nahuel Huapi paleolake (known as Lake Elpalafquen) had a higher water level than the current lake. It was closed in on its eastern tip by the terminal moraines of the glaciers that occupied the lake's basin during the last Ice Ages. The paleolake levels fell in three different stages, from 45 m to 17.5 m, and 6 m above the current water levels. These drops were associated with seismic-volcanic events recorded in the sediment cores analyzed by the authors:

"The erosional unconformities identified in the sedimentary cores are covered by tephra layers several centimeters thick, suggesting the existence of seismic events prior to the tephra collapse, similar to those recorded during the Valdivia earthquake on Lake Nahuel Huapi."

• 19,081 ± 0,274 ky cal BP the water of the paleolake stood 47 m higher than its current, reaching 815 m above sea level.
• The first descent took place 16,840 ± 0,250 ky cal BP.
• Another event 16,381 ± 0,269 ky cal BP also impacted on lake levels cutting off the basin of Lake Guillelmo and Lake Mascardi from the Nahuel Huapi basin, as it modified the marsh that separates Mascardi from Lake Gutierrez, leading the former to drain towards the Pacific Ocean (through the Manso and Puelo rivers), and shifting the continental watershed eastwards.
• 15,537 ± 0,249 ky cal BP the lake level dropped to 17.5 m above its present level.
• Followed by another decrease 14,680 ± 0,261 ky cal BP that left it 6 m above the current lake level.
• 1,750 years BP the lake dropped to its current level of 768 m above sea level.

These eartquake-induced lake level fluctuations were catastrophic events. The author writes: "It is possible that several of them would have catastrophic characteristics for the Limay River basin, dumping a large volume of water in a very short time; e.g., the author estimated that a 10-m drop in the Nahuel Huapi Lake basin would contribute a volume of 6.2 km3 of water to the Limay River."

A massive downstream flood.

Lake Elpalafquen and Modern Lakes. Source

So the gradual breakage of the eastern terminal moraine due to quakes led to a lower lake level, and erosion of the moraine between these events reduced the level even further. Notice how in the past, lakes Espejo and Corentoso (top left and right), and Gutierrez, Mascardi and Guglielmo (bottom center) were all linked as long arms to the main body which nowadays is Lake Nahuel Huapi.

These events would have had an impact on any potential cryptid living in the lake's basin.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

Paleolakes Colhue Huapi and Musters

Modern lakes Colhue Huapi and Musters are located in the middle of the Patagonian badlands, in the arid steppe of Chubut province, Argentina. They are surrounded by plateaus and basaltic mesas (see them in Google maps). They were not formed by glacers and are quite a distance from the Andean forests, yet they have an interesting story regarding their origin, and some curious native myths about how they formed.

The origin of Lakes Colhue Huapi and Musters

There was a low-lying area, a depression in the Patagonian steppe south of Mount Puricelli. Which received the output of the Paleo-Senguer river (formed in the Andes by the outflow of lakes Fontana and La Plata, and by several smaller rivers like Rio Mayo, Genoa, and Gato). At the end of the last Ice Age, Senguer carried more water and formed the Sarmiento Paleolake (named after the town that stands beside the modern lakes).

Paleolake Sarmiento covered an area of 4,300 km² (roughly 1,660 sq. mi.) and its surface rose to a level 60 meters above the current lake levels (196 ft.) it was large yet shallow (not more than 80 m - 262 ft).

At first the Senguer River bypassed the depression, flowing along what is the current Chico River valley towards the northeast, meeting the Chubut River and reaching the Atlantic (see a in the image below). The depression was fed by the scant rain that fell in the area.
A dry period followed, and the paleolake shrank (seee b in the image).
It was followed by the capture of the Senguer when a creek that ran along the Valle Hermoso valley eroded upstream and led the Senguer River to flow along it, into the depression (see c in the image). This flooded the depression and the lake grew to its maximum size.

This took place around 8,400 years ago. The lake drained towards the northeast along the valley of the Chico river.

Around 6,000 years ago, a dry period set in, and the Senguer carried less water, this led to a drop in the level of the Sarmiento paleolake. It shrank, and split into the two current lakes, Musters and Colhue Huapi. (see d in the image).

CAPTION HERE. Copyright © 2025 by Austin Whittall

The Native Myths

Berta Vidal de Battini compiled an ancient story told by Aurelio Nahuelquir in 1950 (source), it tells about the flood that formed Lake Colhue Huapi:

"My grandfather said that his grandparents told him that their grandparents said how the Lake Colhue Huapi appeared there. This is very ancient. Many, many years ago, the site of the lake was in those days a deep bog, like the Sacana salt flats. There was grass, and there was water and there were plenty of guanaco and ostrich to huynt. In this spot there was a large population of pure Tehuelches, with their animals and their homes, and all the tools they used, men and women. But, nobody knows how a great tragedy came about like a storm, and water welled up everywhere. They were all covered by the water, submerged the people with their animals, and everything, as if it was a punishment. And, there, this large and very pretty lake was formed, Lake Colhué-Huapí. It seems that an island remained, but it can't be seen. "

Was this an ancestral memory of the capture of the Senguer River and the flood that submerged the Sarmiento depression?

Battini also mentioned a story by Juan Quichanal (1952), from Sarmiento, it tells about the origin of Lake Musters, as a consequence of a camaruco (a traditional ceremony or prayer where they asked their gods for help favors and to ward off misfortunes).

"Many, many years ago, the countrymen of ancient times lived in Lake Musters. My great-uncle told me. He said it was very, very dry, and windy all day. The wind drove them mad. It didn't rain during the whole year. The animals died. There was nothing to eat. The people didn't have anything to hunt... the guanaco had gone far, far away to the hills of the Cordillera. The people had no option but to do a camaruco, a very large camaruco to plead for water and be well.
They say that all the people of the Cordillera sent messages to those in the lowlands to make a camaruco together. A tribe came down from the Cordillera. They all gathered together, and they waited for those people who lived where Lake Musters is. But those people didn't come. It is said that they had done their own separate camaruco and it rained. It rained a lot, a lot, and it formed alare lake. They say that when the other people went down to the lake, it got ancry and the waters rose, and growled, and a strong wind blew. This was the cry of the people that were there, under the waters of the lake. It can be heard from very far. This is what the old people at Lake Musters said."

Lake Creatures

See my posts on the Lake Colhue Huapi creature and the Giant Sloth at Lake Musters.

Both lakes are slowly drying out, due to the use of Senguer's water to irrigate the farms in Sarmiento. Below is a view of each lake: Colhue Huapi, with sand dunes (top), Musters (bottom)

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

Another Paleo-Lake (Puelo)

 

Paleo Lake ca. 1000 BP. By Barzi, A. [1]

When I posted on Vanishing Rivers I mentioned a great Paleo-lake that had formed at the end of the last Ice Age in northern Patagonia. In other posts, I had mentioned also mentioned deglaciation and the formation of the current Patagonian eco regions.

Today I came across a very interesting map by Mr. Alejandro Brazi, at his website which deals with the geography of the small village of El Hoyo and its surrounding areas.[1] It shows how the area that is now occupied by lakes Puelo, Epuyén and the valleys of the rivers Epuyén and Azul, were flooded during the end of the last Ice Age producing a very large paleo-lake.

The lake drained just as it does in the present, to the west, into the Pacific Ocean through a narrow pass in the Andean mountains.

The interesting part of this is that the Patagonian Plesiosaur was said to have been sighted in the Puelo-Epuyén rivers basin in the early 1920s. (see my map showing the current lakes and compare it with the one shown above.

Did the receding waters capture some megafaunal beast and restrict it, keeping it captive in the now smaller lakes?
Dit it originally swim up the Puelo River from the South Pacific Ocean, during the days when Puelo and Epuyén lakes were merged in the giant paleo-lake?

By the way, there have been reports of "monsters" in the Puelo River.

We will never know (neither can we know if there is -or was- a cryptid lake creature here or if it was really sighted in 1922.)

Bibliography.

Barzi, A. Descripcion de El Hoyo. Geografia Fisica

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia

2010 International Year of Biodiversity Copyright 2009-2010 by Austin Whittall © 

Lake Monsters - The origin of their habitat. Part 1

 

If the Patagonian lakes are home to lake “monsters” and mysterious creatures, we can learn more about these cryptids if we study the lakes themselves and their origin.

Patagonian lakes, both in Argentina and Chile are mostly located along the Andes mountain ranges which run in a north-south direction and are cut on an east-west direction by many valleys, some of which are filled with deep freshwater lakes. A few exceptions are lakes set in the steppe (i.e. Lake Colhue Huapi – which is fed by water from the Andean snow melt) some of which lake drainage and are fed by the scarce rainfall.

These Andean lakes were carved by the glaciers during the Ice Ages.

Ice Ages and the formation of lakes

Sixteen different “Ice Ages” have been recorded in the southern tipo of Patagonian mainland during the last 2 million years, and at least six in Tierra del Fuego Island during the last million years.[1]

The most severe of these was the “GGP” or Gran Glaciación Patagónica (Great Patagonian Glaciation), about 1 million years ago. During this event, the ice sheets reached the Atlantic Ocean at the area of the Strait of Magellan. Later glacier advances extended for several hundred kilometers but did not reach the sea (i.e up to 300 km in Tierra del Fuego). [1]

All of Patagonia is strewn with rounded boulders and pebbles created by the glaciers and their melt waters.

The last glacial event began about 25,000 years ago and most of southern Patagonia was covered with glaciers or a frozen tundra with permafrost. Only on certain warmer spots along the sea shore did the Nothofagus forest survive.[1]

Below are some maps showing the areas that were covered by the ice sheets:

Northern Patagonia. From the Internet [*]
The striped area was covered by glaciers. The dotted red line is the border between Chile and Argentina.

Northern Patagonia coverage, detail. From the Internet [*]
In gray the icefields, in black, current glaciers. Arrows show the direction of the ice sheet flow.

Southern Patagonia Ice coverage- note extant icefields in green. From [3].

Ice starts to melt: paleolakes

After deglaciation, the forests retreated together with the glaciers, their source of water, to occupy their current habitat in the Andes, leaving the now arid Patagonian plateau to shrubs and dwarfish bushes (a dry steppe).

During the ice ages, the glaciers and their moraines formed large natural dams that contained what are known as paleolakes. These large bodies of water had very high water levels and drained towards the Atlantic Ocean. The wide and deep valleys that cross the Patagonian steppe from west to east witness the might of the rivers that drained these lakes. Now most of these valleys hold small rivers (i.e. rivers Chico, Coyle, Gallegos) and some even run dry before reaching the coast (i.e. Deseado River).

During the late Pleistocene epoch (between 13,200 and 7,800 years ago), climate grew warmer and the glaciers began melting. This changed not only the weather and local ecology, but also affected the landscape as the paleolakes fragmented into smaller ones and their water level dropped, in some cases below the eastern terminal moraines, blocking their outflow into the Atlantic Ocean, and causing them to empty westwards into the Pacific Ocean.[2]

These paleo lakes were, from north to south, the following [2]

Elpalafquen 41° S. Was a vast lake system that drained through the Limay River into the Atlantic (which still drains many lakes of the eastern slope of the Andes such as Nahuel Huapi, Espejo, Correntoso, Gutiérrez, Moreno, Traful, etc.) it broke up about 13,200 years ago and some lakes began draining into the South Pacific through the Manso River (such as Mascardi, Steffen, Fonck, Guglielmo, Césares, Hess, etc.).

Caldenius 47-48° S, included current lakes Azara, Belgrano, Mogote, Nansen, Volcán and Burmeister, all of which are now part of the Argentine Perito Moreno National Park. It drained into the Atlantic until ten thousand years ago when it also began to drain through a channel cut through the Andes. Its level was over 100 m (300 ft.) higher than the current water level of Lake Belgrano.

Fuegian paleolake 54-55° S, began melting 7,800 years ago. It comprised lakes Fagnano, Yehuin and Chepelmut as well as the Esperanza bog. Nowadays only Esperanza drains towards the Atlantic through the del Fuego River. The other three lakes drain into the Strait of Magellan.

Remnant glaciers

All that remains of these imposing glaciers that once covered a very large surface of Patagonia are two continental ice sheets covering an area of 21,000 km2 (8,110 sq. mi.). These are the third biggest extensions of continental ice after Antarctica and Greenland. Located roughly 73°W and between 47° and 51°30’ S they are fed by the abundant winter snowfall and maintained by frost most of the year; however, they are now imperiled by climate change as can be seen in the following photographs of Upsala Glacier (Southern Icefield), comparing the same view in 1928 and 2004:

Upsala Glacier (49°50' S, 73°17'W) has a surface area of 870 km² (340 sq.mi.) and a length of about 60 km (37 mi.), making it the third largest Southern Hemisphere glacier outside Antarctica,and South America's longest glacier. It is shrinking rapidly. See Fig. 53 [3] which shows a map with the retreating front of this glacier (1968-1995).

See my photograph of the glacier in my post Here.

Northern Patagonian Icefield (47°00’S, 73°39’W) is about 120 km long (74 mi.) and 40-60 km wide (25 – 37 mi.) and covers an area of 4,200 km² (1,640 sq. mi.), capping the Andes.

Southern Patagonian Icefield (between 48°50’S and 51°30’S is about 40 km wide and covers a larger area (13,200 km², about 5,150 sq.mi.). This is the largest mass of ice outside of the Antarctic.

The remaining glaciers are distributed along the tall Andean peaks in smaller icefields, the larges of them is on Tierra del Fuego Island and has a surface area of about 2,500 km² (975 sq.mi.) it straddles Darwin Cordillera and Mount Sarmiento.

Impact on cryptids

From the above we can see that there were no lakes before the Ice Ages (2 million years ago max.). They must have been excavated in a gradual process, by which each successive glaciation dug deeper trough shaped valleys which during the warmer inter-glacial periods filled with water. And were repeatedly filled up again with ice sheets hundreds of meters thick during each new glacial period.

This must have exterminated any animals attempting to colonize these lakes until the last deglaciation some 10,000 years ago.

The current lakes are the remnants of gigantic paleolakes that broke up and split, shedding their water into both oceans. Their fauna prior to the introduction of salmonids in the 1900s was the local endemic Patagonian species, which hitch-hiked their way from lake to lake perhaps on the feet or feathers of the local water fowl.

This excludes the existence of any large "non-fish" freshwater creatures such as plesiosaurs and so on.

Large tropical mammals could have moved into the now arid Patagonia, but if they were aquatic creatures accustomed to the warmer and more humid conditions prevailing to the north of Patagonia, we must identify how they crossed the dry barren areas that now separate the Patagonian Andean forests from these northern tropical areas.

That is what we will do in our next post Here.

Bibliography.

[1] Coronato, A., Borromei, A., and Rabassa, J. Paleoclimas y Paleoescenarios en la Patagonia Austral y en Tierra del Fuego durante el Cuaternario.
[2] Del Valle, R., Tatur, A., and Rinaldi, C., Cambios en lagos y circulación fluvial vinculados al calentamiento climático del Pleistoceno Tardío-Holoceno Temprano en Patagonia e Isla 25 de Mayo, Islas Shetland del Sur, Antártida. Revista de la Asociación Geológica Argentina 62 (4): 618- 626 (2007)
[3] USGS. Historic Fluctuations of Outlet Glaciers from the Patagonian Ice Fields. Fig. 54.

Further Reading:

Glasser, N., Harrison, S., Winchester, V., and Aniya, M. Late Pleistocene and Holocene palaeoclimate and glacier fluctuations in Patagonia . Global and Planetary Change, Volume 43, Issues 1-2, August 2004, Pages 79-101.



Copyright 2009 by Austin Whittall ©

Patagonian Monsters