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Reawakening of large earthquakes in south central Chile: The 2016 M w 7.6 Chiloé event
Author(s) -
Ruiz S.,
Moreno M.,
Melnick D.,
Campo F.,
Poli P.,
Baez J. C.,
Leyton F.,
Madariaga R.
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 - 10.1002/2017gl074133
Subject(s) - geology , seismology , subduction , mantle (geology) , geodesy , tectonics , geophysics
On 25 December 2016, the M w 7.6 Chiloé earthquake broke a plate boundary asperity in south central Chile near the center of the rupture zone of the M w 9.5 Valdivia earthquake of 1960. To gain insight on decadal‐scale deformation trends and their relation with the Chiloé earthquake, we combine geodetic, teleseismic, and regional seismological data. GPS velocities increased at continental scale after the 2010 Maule earthquake, probably due to a readjustment in the mantle flow and an apparently abrupt end of the viscoelastic mantle relaxation following the 1960 Valdivia earthquake. It also produced an increase in the degree of plate locking. The Chiloé earthquake occurred within the region of increased locking, breaking a circular patch of ~15 km radius at ~30 km depth, located near the bottom of the seismogenic zone. We propose that the Chiloé earthquake is a first sign of the seismic reawakening of the Valdivia segment, in response to the interaction between postseismic viscoelastic relaxation and changes of interseismic locking between Nazca and South America.