First results from seismicity and local earthquake tomography in the Villarrica-Valdivia region, South-Central Chile.

Dzierma, Yvonne, Thorwart, Martin, Siegmund, Claudia, Rabbel, Wolfgang, Comte, D., Bataille, K., Iglesia Llanos, M. P. and Prezzi, C. (2010) First results from seismicity and local earthquake tomography in the Villarrica-Valdivia region, South-Central Chile. [Poster] In: SFB 574 Subduction Workshop. , 04.-07.11.2010, Pucon, Chile .

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Abstract

The region north of Villarrica Volcano and the rupture zone of the 1960 Valdivia earthquake have been studied extensively. However, previous work focused on the parts of the plate interface adjacent to the epicentre and did not cover the area of maximum slip (39–42°S). This region has been considered a seismic gap due to the scarcity of local earthquakes registered in this region; this is consistent with a locked plate interface upon which significant strain can accumulate. To investigate this part of the Chilean margin, the seismology subproject deployed 55 seismic stations between 39° and 40°S, covering the area from
the coast to the back-arc in Argentina. The network was installed in November 2008 and operated for one year, consisting of 40 short-period and 15 broadband seismometers.
The local seismicity is significantly higher than expected, with more than 1000 events out of which about 300 were localized in the area covered by the network. The plate interface where the 1960 slip occurred is free of seismicity. At greater depths, the Wadati-Benioff-Zone can be observed down to 160 km with a dip angle of 30°; some indication for a double Benioff-zone at shallower depths is found. In the continental crust, seismicity is observed related to local fault structures. Some clusters of seismicity occur offshore, associated with the trench and fault structures in the incoming oceanic plate. In addition to the seismicity, we present focal mechanisms and first results from local earthquake tomography.

Document Type: Conference or Workshop Item (Poster)
Keywords: Geodynamics; subduction; earthquake; seismology, Chile; Villarrica
Research affiliation: OceanRep > SFB 574
OceanRep > SFB 574 > A2
Kiel University
Date Deposited: 13 Dec 2010 12:16
Last Modified: 27 Jan 2012 05:03
URI: http://oceanrep.geomar.de/id/eprint/10476

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