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Seismological and Geodetic Investigations in the Atacama Region of Chile: Investigations of Links Between Plate Interface and Intermediate Depth Processes

Description: 

The Atacama region of Northern Chile likely to be a mature seismic gap, with the last segment-breaking great earthquakes in 1819 (Mw~8.0) and 1922 (Mw~8.4). As such it provides the opportunity to study processes during the final stage of the seismic cycle but also the time-dependent hazard can be considered to be severe. Several episodes of silent slip events have been reported from GNSS time series analysis (by Klein et al., 2018), the last one from 2014-2016. The same area is also known to have given rise to several earthquake swarms of plate interface and intermediate depth seismicity, indicating a propensity for transient behaviour. This region is only sparsely sampled by permanent seismic and GNSS stations.

Here we report on preliminary results from the recently completed temporary deployment of more than 100 seismic stations and ~30 continuous GNSS stations, which complement the permanent stations mostly operated by the Chilean seismic network. Automated analysis of data from this network yielded more than 30,000 events which are relocated in a 2D model using a double-difference relocation scheme, with a magnitude of completeness of ~2.0. The located seismicity clearly delineates two bands of seismicity within the oceanic slab, and in some areas, a third one is associated with the plate interface; the upper plate only shows sparse activity. The seismicity can be compared to the plate-locking map derived for the same area. Most of the seismicity is located between an extended offshore locking zone and the shoreline, probably representing the transition to velocity-weakening material. To first order, intensity of intermediate depth seismicity seems to follow the intensity along the plate interface.

Session: Subduction Zone Structure From Trench to Arc [Poster]

Type: Poster

Date: 4/19/2023

Presentation Time: 08:00 AM (local time)

Presenting Author: Frederik Tilmann

Student Presenter: No

Invited Presentation: 

Authors