Combining seismic arrays to image the high-frequency characteristics of large earthquakes

This study investigates the source properties of the 2007 8.0 Pisco, Peru, 2007 8.4 and 7.9 Mentawai Islands, Indonesia, 2009 8.1 Samoa Islands and 2010 8.8 Maule, Chile, earthquakes using a backprojection technique that utilizes data from multiple seismic arrays. Combining seismic arrays increases azimuth and distance coverage and improves lateral resolution. The four subduction interface events show rupture propagation towards the bottom of the seismogenic zone. In addition, all of the earthquakes show evidence of multiple rupture segments with varying rupture speeds and directions. Relating these segments to the specific features of the subduction zones (e.g. interseismic coupling) suggests that asperity sizes may be controlled by subtle features of the subducted slab.