Aftershock seismicity and tectonic setting of the 16 September 2015 Mw 8.3 Illapel earthquake, Central Chile.

Lange, Dietrich , Geersen, Jacob , Barrientos, Sergio, Moreno, Marcos, Grevemeyer, Ingo , Contreras-Reyes, Eduardo and Kopp, Heidrun (2016) Aftershock seismicity and tectonic setting of the 16 September 2015 Mw 8.3 Illapel earthquake, Central Chile. Open Access Geophysical Journal International, 206 (2). pp. 1424-1430. DOI 10.1093/gji/ggw218.

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Powerful subduction zone earthquakes rupture thousands of square kilometers along continental margins but at certain locations earthquake rupture terminates. To date detailed knowledge of the parameters that govern seismic rupture and aftershocks is still incomplete. On 16 September 2015 the Mw. 8.3 Illapel earthquake ruptured a 200 km long stretch of the Central Chilean subduction zone, triggering a tsunami and causing significant damage. Here we analyze the temporal and spatial pattern of the co-seismic rupture and aftershocks in relation to the tectonic setting in the earthquake area. Aftershocks cluster around the area of maximum coseismic slip, in particular in lateral and downdip direction. During the first 24 hours after the mainshock, aftershocks migrated in both lateral directions with velocities of approximately 2.5 and 5 km/h. At the southern rupture boundary aftershocks cluster around individual subducted seamounts that are related to the downthrusting Juan Fernández Ridge. In the northern part of the rupture area aftershocks separate into an upper cluster (above 25 km depth) and a lower cluster (below 35 km depth). This dual seismic-aseismic transition in downdip direction is also observed in the interseismic period suggesting that it may represent a persistent feature for the Central Chilean subduction zone.

Document Type: Article
Additional Information: High-resolution multibeam bathymetric data were collected during multiple seagoing campaigns lead or co-lead by GEOMAR Helmholtz Centre for Ocean Research Kiel. The database at GEOMAR combines swath bathymetric soundings from cruises carried out between 1995 and 2010 (e.g. vonHuene et al., 1995, Flueh et al., 2002) and may be accessed through the Ocean Science Information System OSIS-Kiel ( The data was complemented with some swath transects from the National Center for Environmental Information (NCEI) database. - WOS:000379772500050
Keywords: 2015 Illapel earthquake, Aftershock distribution, Subduction zone, Central Chile, Seismogenic zone, Forearc tectonic, RV SONNE, SO161
Research affiliation: Kiel University
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > The Future Ocean - Cluster of Excellence > FO-R06
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1093/gji/ggw218
ISSN: 0956-540X
Projects: Future Ocean
Date Deposited: 14 Jun 2016 07:28
Last Modified: 23 Sep 2019 22:32

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