Heterogeneous structure of the Northern Chile marine forearc and its implications for megathrust earthquakes. Issue 2 (6th August 2018)

• Record Type: Journal Article
• Authors: Maksymowicz, Andrei; Ruiz, Javier; Vera, Emilio; Contreras-Reyes, Eduardo; Ruiz, Sergio; Arraigada, César; Bonvalot, Sylvain; Bascuñan, Sebastián
• Is Part Of: Geophysical journal international. Volume 215:Issue 2(2018:Nov.)
• Page Start: 1080
• Page End: 1097
• Publication Date: 2018-08-06
• Subjects: Composition and structure of the continental crust -- Fault zone rheology -- Gravity anomalies and Earth structure -- Seismicity and tectonics -- Dynamics: seismotectonics; Geophysics -- Periodicals; 550
• DOI: 10.1093/gji/ggy325
• Languages: English
• ISSNs: 0956-540X

Abstract

SUMMARY: Recent studies have proposed that nucleation zones, seismic barriers and high-slip patches of megathrust earthquakes correlate with physical heterogeneities, both in the oceanic/subducting plate and in the continental wedge. We present a density-depth model along the Nazca-South America subduction margin, from 18°S to 23°30′S, where a partial segment of this zone was ruptured by the M w 8.2 Iquique earthquake on 2014 April 1. The density modelling and interpretation were constrained with seismic reflection profiles, published Vp -depth tomographic models and relocated seismicity. These results were used to estimate the variability of normal stress on the seismogenic contact. Our results show a heterogeneous structure for the Northern Chile marine forearc. In particular, we observed a latitudinal and longitudinal segmentation of continental wedge properties, where changes in density can be explained by changes in fracturing degree, which could have an important control on the Iquique earthquake rupture process. This study provides new insights into the analysis of large earthquakes and seismic/tsunami hazard in this active segment of the Chilean margin.