3D NearField Surface Deformation, Stress and Friction of the 2023 Mw 7.8 and Mw 7.6 Kahramanmaras Earthquakes Measured by Alos2, Sentinel1 and Sentinel2 Pixel Offsets
The variation of stress on faults is important for our understanding of fault friction and the dynamics of earthquake ruptures. However, we still have little observational constraints on absolute stress magnitudes, or their variations in space and in time over the seismic cycle. Here, we use 3D surface deformation measurements in the nearfield of the 2023 Mw 7.8 and Mw 7.6 Kahramanmaras earthquakes to estimate the distribution of 3D slip vectors along both ruptures and invert them for the stress state and frictional properties, using the approach of Milliner et al. (2022). To estimate the 3D coseismic surface deformation we invert azimuthal and range pixel offsets estimated from ascending and descending Sentinel1 and descending ALOS2 radar data. Radar were processed using ISCE, and pixel offsets from Sentinel2 optical imagery estimated using the newly developed COSICorr+ software. The coseismic slip magnitude shows a marked decrease of ~3 m along a restraining bend of the Mw 7.8 mainshock rupture. We assume this reflects the quasistatic effect of a decrease in the initial shear stress due to the change of the fault geometry with respect to the ambient stress field. We use this to invert for the static and dynamic friction of the ruptured faults and the absolute stress magnitude and its orientation.
Session: February 2023 Mw 7.8 Earthquake Sequence in Turkey
Type: Oral
Room: 201 A/B
Date: 4/19/2023
Presentation Time: 11:00 AM (local time)
Presenting Author: Chris W. D. Milliner
Student Presenter: No
Additional Authors
Chris Milliner Presenting Author Corresponding Author geomilliner@gmail.com California Institute of Technology 
JeanPhilippe Avouac avouac@caltech.edu California Institute of Technology 
Danielle Lindsay danielle.lindsay@berkeley.edu University of California, Berkeley 
Sezim Güvercin sezim.guvercin@gmail.com Boğaziçi University 
Ozgun Konca ozgun.konca@boun.edu.tr Boğaziçi University 
Roland Burgmann burgmann@berkeley.edu University of California, Berkeley 
Saif Aati saif@caltech.edu California Institute of Technology 


3D NearField Surface Deformation, Stress and Friction of the 2023 Mw 7.8 and Mw 7.6 Kahramanmaras Earthquakes Measured by Alos2, Sentinel1 and Sentinel2 Pixel Offsets
Category
February 2023 Mw 7.8 Earthquake Sequence in Turkey
Description