I am interested in how EQ relates to tectonics to understand better the past, present, and future. To do so, I apply, in collaboration, many geophysical techniques and observations (slab bending flexural models, refraction and reflection seismic data, kinematic earthquake modeling, gravimetry, and topography analysis) to reveal why EQs stop and their relationship with tectonic features. For instance, we have modeled the incoming plate’s flexural bending, providing insights into the role of sediments in the subduction channel thickness, as well as their potential influence on large megathrust EQ ruptures in Southern Chile.
+ +I also worked in the northern Chile subduction zone in the regions struck by the $M_w$ 7.7 Tocopilla (2007) and $M_w$ 8.1 Iquique (2014) earthquakes. In the case of the first EQ, we modeled seismic data and cross-correlated with Tocopilla EQ relocated aftershocks, revealing a bending from 10$^{o}$ to 22$^{o}$ in the slab geometry. We interpret the coastal scarp as a surface expression of this slab-dip change. Such a change in the dip acts as a barrier for EQ rupture towards the trench, implying that the megathrust is segmented along-strike as well as along-dip. In the case of Iquique EQ, we studied its rupture process (and its bigger aftershock) using a kinematic inversion in the frequency domain. Slip models are segmented along-strike and dip. We find that along-strike segmentation is associated with changes in the lithology and fluid content inside the continental wedge, whereas along-dip by a change in the slab dip, which is also associated with a change in the EQ frequency content.
+ +These results are very relevant because the traditional definition of a seismic gap considers the recurrence time between EQs in a given region, considering only the along-strike segmentation and not the event location at depth. Our results demonstrate that seismogenic zones are also segmented along-dip. This feature must be considered for a more reliable EQ hazard assessment, which is also supported by analysis of historical catalogs. Additionally, such results describe the importance of fault geometrical complexities in the EQ rupture process along subduction settings and, thus, its link with tectonics.
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(a) Iquique EQ data (blue) and synthetic seismograms (red) along with its kinematic slip model (b). (c) High-resolution topography and (d) free-air gravity anomaly. Mainshock (green) and aftershock (pink) slip contours are plotted. Violet line represents the location of an abrupt change on dip angle of the slab
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