Seismic and aseismic fault slip during the initiation phase of the 2017
Mw=6.9 Valparaiso earthquake.
Emmanuel Caballero
Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS, Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS, Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS
Corresponding Author:[email protected]
Author ProfileZacharie Duputel
Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS, Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS, Institut de Physique du Globe de Strasbourg, UMR7516, Université de Strasbourg/EOST, CNRS
Author ProfileAbstract
Transient deformations associated with foreshocks activity has been
observed before large earthquakes, suggesting the occurrence of a
detectable pre-seismic slow slip during the initiation phase. In this
respect, a critical issue consists in discriminating the relative
contributions from seismic and aseismic fault slip during the
preparation phase of large earthquakes. We focus on the April-May 2017
Valparaíso earthquake sequence, which involved a Mw=6.9 earthquake
preceded by an intense foreshock activity. To assess the relative
contribution of seismic and aseismic slip, we compare surface
displacements predicted from foreshock source models to the transient
motion measured prior to the mainshock. The comparison between observed
and predicted displacements shows that only half of the total
displacement can be explained by the contribution of foreshocks. This
result suggests the presence of aseismic preslip during an initiation
phase preceding the mainshock.