Geotechnical Reconnaissance of the 2015 Mw8.3 Illapel, Chile Earthquake

Abstract

The Mw 8.3 event that affected the Illapel area was triggered at 22:54:32 (UTC) on September16th of 2015, with hypocentral location 31.5530°S, 71.8640°W, and 8.2 km deep, as reportedby the Chilean National Seismological Center (CSN). As it occurred in the Iquique 2014,and Maule 2010 events, this earthquake filled a large seismic gap (Figure 2.1) between the1985 Mw 7.9 Valparaiso earthquake and the 1922 Mw 8.7 event. The gap had previouslyruptured on the 1943 Mw 7.9 and the great 1730 Mw 8.7 events as well as a relatively minorevent, the 1880 Mw 7.7 earthquake as reported by Nishenko (1991). The event was recordedby 17 strong motion stations, and 15 GPS stations. While an important number of aftershockswere triggered, no significant precursor activity is reported.