Geological underwater survey: Laguna Azul

Expedition Mundo Azul:
Searching for a hidden volcano in the sea floor of Laguna Azul

Location: Laguna Azul, Peru
Altitude: 700 m
Maximum length of the lake: 5 kms
Total surface area: 430 ha
Maximum depth: 37 m
Year of expedition: 2000

Participants: Stefan Austermühle, Nina Pardo, Klaus Storch, Hitti Storch

Goal:

  • Confirm the presence of a volcano on the bottom of the Blue Lagoon (Laguna Azul) in Tarapoto, Region of San Martin.

Results:

The Blue Lagoon (Laguna Azul) is situated around 40 kilometers from the city of Tarapoto and 16 km from the right side of the Huallaga River in the District of Sauce, in the Region of San Martin. Laguna Azul is one of the principal tourism destinations of the District of Sauce. According to literature, the Lagoon’s origin is a tectonic event. Locals reported that sometimes the water starts stinking like sulfur and fish die. This raised the question of the possibility of a presence of an active volcano on the sea floor. The expedition’s goal was to screen the lake with Mundo Azul´s sediment sonar in order to confirm the presence of a sub-aquatic volcano.

The lagoon can be divided in two parts – A larger part, being very shallow (maximum depth: 7 meters) and a smaller part with a maximum depth of 37 meters. As the graphics with one of the sonar transects shows, the volcano could be located on the bottom of the deeper part of the lake. The image shows the opening of the volcano, being covered with a thin layer of very soft sediment. Sulfur gas seems to penetrate this layer in order to dissolve when rising up from the volcano and poisoning the water periodically, causing the fish mortalities.

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Page author: Stefan Austermühle