ABSTRACT

Local seismic broadband recordings of the Integrated Plate boundary Observatory Chile (IPOC) are used to determine rupture directions for 60 M5.0 events in the foreshock and aftershock series of the 2014 Mw 8.1 Iquique earthquake in northern Chile. The applied method is based on accurate measurements of the P‐wave coda polarization, which exhibits systematic, azimuth‐dependent variations with time as the earthquake rupture propagates. We demonstrate a general consistency with observations from teleseismic backprojection studies for the main event and its largest foreshock (Mw 6.7) and aftershock (Mw 7.6). A large portion of the here analyzed events show unilateral rupture behavior, with a predominance of down‐dip (east) oriented directivity.

This study documents the potential of retrieving rupture directions for M5 earthquakes from a high‐quality local seismic monitoring system.

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