Source model of the 16 September 2015 Illapel, Chile, M<inf>w</inf> 8.4 earthquake based on teleseismic and tsunami data

We proposed a source model for the 16 September 2015 Illapel (Chile) tsunamigenic earthquake using teleseismic and tsunami data. The 2015 epicenter was at the northernmost of the aftershocks zone of the 2010 Mw 8.8 Maule earthquake. Teleseismic body wave inversions and tsunami simulations showed optimum rupture velocities of 1.5–2.0 km/s. The agreement between observed and synthetic waveforms was quantified using normalized root-mean-square (NRMS) misfit. The variations of NRMS misfits were larger for tsunami data compared to the teleseismic data, because tsunami waveforms are more sensitive to the spatial distribution of slip. The large-slip area was 80 km (along strike) × 100 km (along dip) with an average slip of 5.0 m and depth of 12–33 km, located ~70 km to the northwest of the epicenter. We obtained a seismic moment of 4.42 × 1021 Nm equivalent to Mw 8.4. Results may indicate a northward stress transfer from the 2010 Maule earthquake.Teleseismic data were provided by the Incorporated Research Institutions for Seismology (http://www.iris.edu/wilber3/find_event). Tide gauge data can be found at the Intergovernmental Oceanographic Commission website (http://www.ioc-sealevelmonitoring.org/). DART records were provided by NOAA (http://nctr.pmel.noaa.gov/Dart/). Earthquake catalogs by the USGS National Earthquake Information Center (http://earthquake.usgs.gov/earthquakes/search/) and Global Instrumental Earthquake Catalogue (1900-2009) of International Seismological Centre Global Earthquake Model (http://www.globalquakemodel.org/what/seismic-hazard/instrumental-catalogue/) were used in this study. We used the GMT software for drawing the figures [Wessel and Smith, 1998]. This article benefited from constructive review comments by Costas E. Synolakis (University of Southern California, USA) and Yuichiro Tanioka (Hokkaido University, Japan) for which we are grateful. We acknowledge financial supports from the Japan Society for the Promotion of Science