Multiple slow‐slip events during a foreshock sequence of the 2014 Iquique, Chile Mw 8.1 earthquake

Abstract

AbstractTo obtain a precise record of the foreshock sequence before the 2014 Iquique, Chile Mw 8.1 earthquake, we applied a matched filter technique to continuous seismograms recorded near the source region. We newly detected about 10 times the number of seismic events listed in the routinely constructed earthquake catalog and identified multiple sequences of earthquake migrations at speeds of 2–10 km/d, both along strike and downdip on the fault plane, updip of the main shock area. In addition, we found out repeating earthquakes from the newly detected events, likely indicating aseismic slip along the plate boundary fault during the foreshock sequence. These observations suggest the occurrence of multiple slow‐slip events updip of the main shock area. The final slow‐slip event migrated toward the main shock nucleation point. We interpret that several parts of the plate boundary fault perhaps experienced slow slip, causing stress loading on the prospective largest slip patch of the main shock rupture.