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miércoles, 2 de abril de 2014

8.2Mw Offshore northern Chile - 1st April 2014 Earthquake Interseismic coupling model

On April 1, 2014 a large earthquake 8.2Mw (USGS) occurred in northern Chile. The fast convergence of the Nazca plate beneath the South American continent (~7cm/yr) is traduced in a locking of a thrust faulting at their contact. The focal mechanism solution delivered by different research institutions and universities is consistent with slip on the  interplate megathrust. In 2011 Chlieh et al (JRG) estimated an interseismic coupling model for northern Chile. They found and asperity that correlates with the rupture area of the earthquake occurred yesterday. 
I prepared a map showing the interseismic coupling model obtained by Chlieh et al (2011). It shows an asperity located just there in same place of the rupture area of the 8.2Mw 1st Apr. earthquake. This map shows also the focal mechanisms solutions from the USGS, for the mainshock 8.2Mw and the recent 7.6Mw event, that seems to have broken another southward small asperity, which has been mapped also by the coupling model. The epicentral location of these events is denoted by the yellow and green stars, respectivelyThe foreshocks (10 days before the mainshock) and the aftershocks so far (2nd Apr), were taken from the Centro Sismológico Nacional de Chile, and are showed in blue stars. 
Note that south of the rupture area of this large earthquake, there is still a considerable asperity that has not broken yet, which correlates with the presumed rupture area of the past 1877 (~M8.5). An important amount of stored energy will be released there... when???...

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