Ongoing seismological investigations around Villarrica volcano, southern Chile

DZIERMA, Y.; THORWART, M.; RABBEL, W.; COMTE, D.; LEGRAND, D.; BATAILLE, K.; IGLESIA, P.; PREZZI, CLAUDIA BEATRIZ

Göttingen, Alemania

Simposio; 21st Colloquium on Latin American Earth Sciences; 2009

As part of the collaborative research centre SFB 574, the Chilean subduction zone is being investigated by a seismological subproject conducted by Chilean, Argentinian and German partners. The general goal of the SFB 574 is to study the origin and influence of volatiles and fluids in subduction zones. The seismological subproject constitutes the structural and seismotectonic framework of these investigations. In addition to presenting a continental end-member of subduction zones, seismicity and volcanism in the Chilean subduction zone are strongly influenced by sediment input into the trench, oblique convergence and strain partitioning, and pre-Andean characteristics of the overriding plate. Furthermore, the occurrence of the largest instrumentally recorded earthquake, the Valdivia 1960 earthquake, close to the very active Villarrica volcano, makes this region ideally suited for subduction-related hazard investigations. A network of 55 seismological stations was installed in November 2008 between 39 deg and 40 deg South. The stations are distributed from the coast to the back-arc in Argentina, linking Villarrica Volcano with the area of maximum coseismic slip of the 1960 Valdivia earthquake. The data collected by this network will serve for local and teleseismic tomography, seismicity, receiver function and anisotropy studies. This poster will present first data examples. In addition to exploring the deep structure and geometry of the subduction zone, these studies will provide insight into the presence of fluids, fluid pathways,and the stress field. In combination with geochemical and volcanological studies also performed by the SFB 574, these investigations will contribute to a better understanding of subduction zone characteristics in a region of extreme coseismic stress, slab-arc fluid processes, volcano dynamics and hazards.