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Months‐Long Crustal Deformation Driven by Aseismic Slips and Pore Pressure Transients Triggered by Local and Regional Earthquakes
Author(s) -
Lu Zhou,
Wen Lianxing
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 - 10.1029/2021gl095148
Subject(s) - geology , pore water pressure , seismology , borehole , poromechanics , deformation (meteorology) , slip (aerodynamics) , san andreas fault , fault (geology) , elastic rebound theory , geotechnical engineering , oceanography , physics , porous medium , porosity , thermodynamics
Strong strain and pore pressure changes are observed after three Mw 4.5+ local and one Mw 7.2 regional earthquake during 2010–2017 in borehole strainmeters near Anza, California. The strain change emerges immediately after the earthquakes and lasts 40–100 days with amplitudes up to 10 −7 , larger than the coseismic strain offsets. The pore pressure exhibits change immediately after the earthquakes at some boreholes and with a delay of 4–10 days at the others. A joint analysis of the observed postseismic strain and pore pressure change suggests that the postseismic strains could be explained by combined effects of poroelastic deformation due to earthquake‐induced pore pressure change and elastic deformation due to an earthquake‐triggered aseismic slip on a local fault. Our study indicates that, in addition to possible aseismic fault slips triggered by an earthquake, pore pressure changes after the earthquake could be even more important in producing postseismic deformation.