Short-Term Bidirectional Interaction between Slow Slip Events and Three Devastating Earthquakes in Mexico

Date: 4/24/2019

Time: 08:45 AM

Room: Cascade II

Triggering of dynamic instabilities in a fault hosting aseismic slip or, inversely, triggering of slow earthquakes by seismic waves far from the source have been a major research topic in the last years mainly from the theoretical and experimental points of view. Only a few observations of one kind or the other plausibly suggest that such interactions actually happen in nature. In this study we show that the recent 2017-2018 devastating earthquakes in central Mexico (i.e. Mw8.2 of September 8, 2017; Mw7.1 of September 19, 2017; and Mw7.2 of February 16, 2018), two of them intraslab events, can be explained as a cascade of events causally related with slow slip transients in the plate interface at a regional scale, in the states of Guerrero and Oaxaca, that preceded or succeeded their ruptures. By means of newly developed and powerful methods, we analyze continuous nationwide geodetic and seismological data (i.e. GNSS and strong motion records onshore, and ocean bottom pressure gauges offshore) for (1) imaging the temporal evolution of aseismic slip and interseismic coupling in a period including and spanning beyond the 5 months comprising the three earthquakes; (2) imaging the evolution of Coulomb failure stresses in the plate interface and the seismogenic faults; and (3) estimating the dynamic stresses and strains at the interface produced by the seismic waves of the events. Our results suggest that both co-seismic and slow crustal deformations during the 1.5-years analyzed period are the consequence of quasi-static or dynamic bidirectional interactions between slow and devastating earthquakes in an unprecedented short-term cascade of events that killed more than 471 people in central and southern Mexico.

Presenting Author: Victor M. Cruz-Atienza

Authors