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Real Time Characterization of Earthquakes in the Mexican Subduction Zone Based on a Seismogeodetic Network

Description: 

A twenty-station seismogeodetic network operates in the Mexican subduction zone spanning the states of Guerrero and Oaxaca. The stations are composed of a GNSS receiver, and the geodetic data are applied an RTX correction in real time and a Kalman filter based on the input of a forced balance accelerometer. Tests show that the resulting real time displacement using these two corrections is as accurate as the post-processed data. Based on these data, the static displacement of large and great earthquakes is estimated. An algorithm was developed to continuously monitor coastal deformation along the subduction zone for potential coseismic displacement. The algorithm triggers when three adjacent seismogeodetic stations report deformation of the coast. The observed horizontal components of the geodetic data are rotated to coincide with the strike and dip of the subduction zone. The source area and length are inverted using Okada´s formulation based on the deformation data recorded by the seismogeodetic instruments. The inversion is done using simulated annealing. The result of the inversion allows the real time estimation of source size and magnitude of large and great earthquakes, for which the national seismic network normally saturates. No large or great earthquakes (Mw >7.5) have taken place in the Mexican subduction zone since the installation of the seismogeodetic network. The algorithm was tested using three recent great earthquakes for which there are coseismic deformation data: the Maule and Illapel earthquakes in Chile in 2010 and 2015 and the Tohoku, Japan event of 2011. The magnitude and source dimensions obtained by the inversion simulating real time acquisition of the geodetic data of the Chilean earthquakes agree with those presented by other authors. In the case of the Tohoku earthquake, the magnitude and source dimension were underestimated probably because the geodetic stations on land are far from the rupture area. Our results show that the seismogeodetic network in the subduction zone is capable of characterizing in real time the source and magnitude of large and great earthquakes.

Session: Performance and Progress of Earthquake Early Warning Systems Around the World - II

Type: Oral

Date: 4/16/2025

Presentation Time: 11:00 AM (local time)

Presenting Author: Gerardo

Student Presenter: No

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