The footprints of past earthquakes revealed in the afterslip of the 2010 Mw 7.8 Mentawai tsunami earthquake

The footprints of past earthquakes revealed in the afterslip of the 2010 Mw 7.8 Mentawai tsunami earthquake

Event Type: 

  • Seminar

Venue: 

EOS Seminar Room - N2-01B-28

Date: 

13 May, 2016 - 16:00

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: 

Feng Lujia

Dr Feng Lujia is a Senior Research Fellow at the Earth Observatory of Singapore (EOS), Nanyang Technological University (NTU), Singapore. She received her B.Sc. in Geology and M.Sc. in Structural Geology from Zhejiang University in China, and her Ph.D. in Geophysics from Georgia Institute of Technology in USA. She is a geodesist who has various experiences in using GPS to study tectonic, seismic, and volcanic deformation. Much of her work at EOS has involved analysis and modeling of the deformation signals from the Sumatran GPS Array (SuGAr). She has recently developed her interest in using the atmospheric water vapor information collected by the SuGAr to study the weather and climate over Southeast Asia. Known as “Tectonic Squirrel”, Lujia is hoping to become a “Climate Squirrel” in the near future.

28 Aug 2019

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