Premium
Seismic and Aseismic Fault Slip During the Initiation Phase of the 2017 M W = 6.9 Valparaíso Earthquake
Author(s) -
Caballero Emmanuel,
Chounet Agnès,
Duputel Zacharie,
Jara Jorge,
Twardzik Cedric,
Jolivet Romain
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl091916
Subject(s) - foreshock , seismology , geology , slip (aerodynamics) , deformation (meteorology) , fault (geology) , aftershock , physics , thermodynamics , oceanography
Transient deformation associated with foreshocks activity has been observed before large earthquakes, suggesting the occurrence of a detectable preseismic slow slip during the initiation phase. 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 M W = 6.9 earthquake preceded by intense foreshock activity. To assess the relative contribution of seismic and aseismic slip, we compare surface displacement predicted from foreshocks source models with 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 pre‐slip during an initiation phase preceding the mainshock.