Diverse Focal Mechanism Solutions of Microseismic Events During Active Deformation in Krysuvik Geothermal Area, SW Iceland, in 2009

Authors: Sigridur KRISTJANSDOTTIR, Kristjan AGUSTSSON, Olafur G. FLOVENZ, Laurent GEOFFROY, Catherine DORBATH
Keywords: microseismicity, focal mechanism solutions
Conference: Stanford Geothermal Workshop Session: Geophysics
Year: 2014 Language: English
Abstract: Krysuvik is a geothermal area located on the Reykjanes Peninsula in southwest Iceland. The peninsula is an oblique spreading plate boundary, striking N80°E compared to the spreading direction of N102.1±1.1°E (DeMets, et al. 1994). Early in 2009 a signal of uplift was detected in the area. The uplift continued until the fall of 2009 when the area started subsiding. Another period of uplift started in April 2010 and lasted until the beginning of 2012 when the area began subsiding again. Intense seismic swarms were recorded on a dense seismic network located in the area during the period of unrest in 2009. Altogether over ten thousand earthquakes were detected. The activity was characterized by short, intense swarms in between longer, quieter periods. A detailed analysis was performed on the focal mechanism solutions of ~1,000 events. Earthquakes of different faulting types characterize individual swarms, with normal, reverse, and strike-slip events taking place in the same swarms.
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