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Nucleation Phase and Dynamic Inversion of the M w 6.9 Valparaíso 2017 Earthquake in Central Chile
Author(s) -
Ruiz S.,
AdenAntoniow F.,
Baez J. C.,
Otarola C.,
Potin B.,
Campo F.,
Poli P.,
Flores C.,
Satriano C.,
Leyton F.,
Madariaga R.,
Bernard P.
Publication year - 2017
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 - 10.1002/2017gl075675
Subject(s) - geology , seismology , foreshock , induced seismicity , asperity (geotechnical engineering) , slip (aerodynamics) , aftershock , physics , geotechnical engineering , thermodynamics
The Valparaiso 2017 sequence occurred in the Central Chile megathrust, an active zone where the last mega‐earthquake occurred in 1730. Intense seismicity started 2 days before the M w 6.9 mainshock, a slow trenchward movement was observed in the coastal GPS antennas and was accompanied by foreshocks and repeater‐type seismicity. To characterize the rupture process of the mainshock, we perform a dynamic inversion using the strong‐motion records and an elliptical patch approach. We suggest that a slow slip event preceded and triggered the M w 6.9 earthquake, which ruptured an elliptical asperity (semiaxis of 10 km and 5 km, with a subshear rupture, stress drop of 11.71 MPa, yield stress of 17.21 MPa, slip weakening of 0.65 m, and kappa value of 1.98). This earthquake could be the beginning of a long‐term nucleation phase to a major rupture, within the highly coupled Central Chile zone where a megathrust earthquake like 1730 is expected.