Seismic structure of the north Chilean continental slope between 19-21ºS using multichannel seismic reflection and refraction data
Abstract
The northern Chilean subduction zone is widely recognized as an erosive convergent margin due to the lack of sediment contribution from the continent to the trench, landward migration of the volcanic arc during the past 100 Myr, and long-term subsidence. There is also a well-studied seismic gap, where no major earthquakes (Mw>8.5) have occurred since 1877. Although some studies have been developed in recent years regarding the geologic and seismic structure of the margin, there are still some features of the structure and tectonic scheme that remain poorly understood. This study is part of the PICTURES (Pisagua/Iquique Crustal Tomography Improves Understanding of Region of the Earthquake Source) project, whose main goal is to understand the role of geologic structures in the upper plate on the distribution of slip during the 2014 Mw 8.2 Pisagua/Iquique earthquake sequence offshore northern Chile and its relationship to regional seismicity. A grid of 2D seismic reflection and refraction data were acquired during cruise MGL1610 of the R/V Langseth; sources were also recorded on ocean bottom seismometers to generate a 3D velocity model. The goal of the work presented here is to analyze variability in the shallow structure of the margin between 19 and 21ºS. For this purpose, four ~150 km long trench-perpendicular reflection lines were processed following standard reflection seismic procedures. P-wave 2D velocity sections were also obtained following a travel time tomography inversion procedure using times of refracted waves observed on the 8-12-km long multichannel streamer, which results in dense spatial resolution of Vp to a depth of ~3 km. Seismic reflection and velocity sections are then jointly interpreted to better understand tectonic processes and seismicity in this region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T51H0407G
- Keywords:
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- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY