Towards a Precise Modelling of the El Salvador Fault Zone Using Geodetic Techniques

Abstract

The El Salvador Fault Zone (ESFZ) comprises a set of a strike-slip faults, extending through the Central American VolcanicArc within El Salvador, where the Cocos plate subducts under the Caribbean plate. These structures act as a boundarybetween the forearc sliver and the western margin of the Chortís block, accommodating the relative movement betweenthem. The ESFZ has been responsible for several shallow, destructive earthquakes in El Salvador, thus posing a seriousthreat for millions of inhabitants. Understanding its seismic potential and the behaviour of its different segments results ofgreat importance for the assessment and mitigation of seismic risk in the region. Geodetic techniques, such as GNSS andInSAR, are useful tools for measuring surface deformation related to tectonic activity. We are in the process of updatingand densifying the existing GNSS velocity field in El Salvador, aiming to characterise the individual faults in the region bydetermining their slip rates and locking depth. Additionally, we will process InSAR data, trying to obtain a continuousmeasurement of the interseismic deformation. The combination of this information with other data (e.g. seismological andgeological) through kinematic models will allow us to better understand the factors controlling the seismogenic behaviourof the ESFZ faults, evaluate their seismic potential and improve the seismic hazard assessment.