Lacustrine records of seismo-volcanic events in Andean Patagonia

VILLAROSA, GUSTAVO; CHAPRON, EMANUEL; OUTES, VALERIA; BEIGT, DÉBORA; ARIZTEGUI, DANIEL; GOMEZ EDUARDO A.

Conferencia; IAL IPA 2022 Lakes as Memories of the Landscape; 2023

IAL IPA

The Andean Patagonia is characterized by strong geodynamic activity associated to the South American Pacific active margin. Intense seismicity originated in the Liquiñe-Ofqui Fault System and the Andean Transverse Faults and volcanic activity from the Southern Volcanic Zone are typical in the North Patagonian Andes. Atmospheric circulation at this latitude is dominated by westerly winds which controls the dispersion of explosive plumes, driving them predominantly to the East. Consequently, the lakes located east of the Andes are a valuable resource for reconstructing the volcanic and seismic activity o history of the region. In the last two decades several works have provided abundant paleoseismological and tephrochronological information for the region. An interesting association of seismic and volcanic signals were identified for several postglacial episodes that has been referred to as seismovolcanic events, the most recent of which was the Valdivia earthquake, followed within hours by the concomitant derived subsequent Cordon Caulle eruption in 1960. This paradigmatic episode had devastating effects in Bariloche where a major underwater slide on the port area and consequent tsunami destroyed the Puerto San Carlos pier, killing two people and sinking several ships? And 40 hours later was impacted by the Cordon Caulle tephra fall event. Similar association of seismic, tsunamigenic mass wasting and volcanic impacts occurred in other localities in Chile and Argentina. Lago Frias record also shows seismic deposits associated with the 1960 CC tephra. Other two important seismovolcanic events have been clearly identified in lacustrine records from the region: one of them associated to the Nahuel Huapi Tephra (Playas Blancas Negra, Naranjo et al. 2017) an important regional tephrochronological marker dated at 2,?? (ver Alloway et al 2021) and a previous one identified as ceiling collapses in two archaeological sites associated with a basaltic andesitic tephra attributed to Osorno volcano identified at Lago Trebol cores and dated at as? 12,4-12.1 ka cal BP.