ANR project SSDYN (2022 - 2025)

SSDYN - Identifying Slow Slip DYNamics combining seismic and geodetic data

Project Objectives

The main objective of this project is to gain knowledge about aseismic slip processes on a large spectrum of spatial and temporal scales. We combine seismic and geodetic data to capture details of slow slip dynamics. The project focusses on the Mexican subduction zone, an ideal and almost unique natural laboratory to study these processes, thanks to the suitable plate geometry (short trench to coast distance, flat slab) and the great variety of the slow slip processes observed.

Study Area

This project combines a large-scale target (left map below), in which we plan to analyze the various slow slip processes over this large plate boundary, to constrain their processes and characterize the interactions; and a small scale target in the Oaxaca region (right map below)) in which a denser instrumentation will allow to decipher the details of slow slip dynamics.

Geodynamic context, previously identified events and available data. (A) Large scale map of the Mexican subduction with major earthquakes (gray), SSEs (blue) and tremors (green). GNSS stations (blue triangles), broadband seismic stations from SSN (red triangles) and Descending Sentinel-1 tracks are represented. Past SSEs and tremors have been identified in Guerrero and Oaxaca. Tremors also occur in Jalisco, Colima and Michoacán, but so far not associated with detectable SSEs. At this scale we will rely on GNSS stations (blue triangles), broadband seismic station from SSN (red triangles) and InSAR (shown are Descending Sentinel-1 tracks) for our analysis. (B) Zoom on the Oaxaca region where a large tremor area is located slightly downdip from the mai SSE region. The three additional seismic stations (big orange triangles) will be installed to monitor tremors, in addition with 20 new GNSS sites installed by UNAM (filled blue triangles).