The footprints of past earthquakes revealed in the afterslip of the 2010 Mw 7.8 Mentawai tsunami earthquake
About the Event:
The 2010 Mw 7.8 Mentawai tsunami earthquake marks one of the first tsunami earthquakes that have postseismic deformation observed by geodetic instruments. The Sumatran GPS Array (SuGAr) has recorded the postseismic deformation following this 2010 event continuously for more than five years. The spatio-temporal evolution of the postseismic deformation is incredibly well explained by velocity-strengthening frictional sliding on the Sunda megathrust. Both the postseismic data and our quasi-dynamic models suggest that the afterslip must have progressed downdip relative to the 2010 coseismic rupture. The southeastern portion of the afterslip region clearly overlaps the area that had slipped during the mainshock and afterslip of the 2007 Mw 8.4 Bengkulu earthquake, while the northwestern portion slipped a region that had been mainly locked. We also show that the afterslip centroid has shifted slightly northwestward along strike relative to the coseismic centroid. This along-strike shift of centroid likely indicates the footprints that recent past slip left in the stress field. By incorporating pre-earthquake stress condition into our quasi-dynamic models, we demonstrate that the cumulative slip from the 2007 Bengkulu mainshock and its afterslip might have caused ~0.1 MPa difference in pre-earthquake Coulomb stress between the southwestern and northwestern portions.
About the Speaker:
“Tectonic Squirrel” Lujia FENG is enjoying her life at EOS so much that she has become one of the oldest members in the postdoc group. She received her B.Sc. in geology and M.Sc. in structural geology from Zhejiang University, China, and her PhD in geophysics from Georgia Institute of Technology, USA. After joining EOS since 2011, she has been primarily working with Emma on the data from the Sumatran GPS array (SuGAr), and she has been also working with a lot of EOS people in various GPS-related projects.