Mora-Stock, C., Thorwart, Martin, Wunderlich, Tina, Bredemeyer, Stefan, Rabbel, Wolfgang and Hansteen, Thor (2012) Multiparameter surveillance of the Llaima and Villarrica volcanoes (Southern Chile): The near real-time approach. [Talk] In: The Lübeck Retreat, Collaborative Research SFB 574 Volatiles and Fluids in Subduction Zones: Climate Feedback and Trigger Mechanisms for Natural Disasters. , 23.-25.05.2012, Lübeck . The Lübeck Retreat: final colloquium of SFB 574; May 23-25, 2012: program & abstracts. ; p. 21 .

Abstract

Llaima and Villarrica are two of the most actives volcanoes in the Southern Volcanic Zone in the
Chilean Andes, with different type of activity and edifice. Llaima is a closed vent volcano with constant
seismic activity, while Villarrica is an open vent volcano with a constantly degassing lava lake at the
summit. Since 2009, seismic networks have been deployed at Llaima and Villarrica, and mini-DOAS
stations continuously recording SO2 degassing were installed in 2010 and 2009, respectively. The
response of Llaima and Villarrica volcanoes to local volcano-seismic activity, to regional events, and
also to the tectonic activity related to the great Maule earthquake (M8.8) in February 2010 are
investigated. Time series for tremors, long period and volcano tectonic events were obtained from the
catalogue of the Volcanic Observatory of the Southern Andes (OVDAS in Spanish) and from the
continuous record of the SFB 574 temporary volcanic network. At Villarrica volcano, peaks of activity
of tremor and long period events were observed months prior to and after the earthquake, which is
consistent with an increase in the activity related to fluids (gas and magma). Degassing at Villarrica
followed a complex pattern, where increased degassing rates preceded the M8.8 Maule earthquake
by three months. Days before the earthquake, there was a strong decrease in degassing, and finally
by a persistent degassing maximum about one month after the earthquake. At Llaima, a high increase
in the volcano tectonic activity was observed directly after the earthquake, consistent with a possible
structural adjustment response. Also, continuous low fumarolic degassing was observed during and
after the earthquake at Llaima, but this activity could be related to the closing of the eruption cycle
started in January 2008. We aim at a better understanding of the volcanic systems through the
combination of both degassing and seismic data, and also detection of satellite-based thermal
anomalies. Ongoing work focuses on the quantification of magma volumes involved, location of
chambers and finally on tomographic structures of Villarrica.

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