Co-Seismic Vertical Deformations of the 30 November 2018 M7.0 Anchorage Earthquake, Alaska

Date: 4/26/2019

Time: 06:00 PM

Room: Grand Ballroom

A M7.0 earthquake occurred on November 30th, 2018, at about 50 km depth and located 14 km NNW of Anchorage, Alaska. This intraplate earthquake caused some major structural damages in and near the city of Anchorage, and aftershock distribution shows significant deformation in the NNE direction of the city. We analyzed co-seismic displacements using Single Look Complex (SLC) Sentinel-1 SAR images in order to understand rupture behavior of this event. We used two Sentinel-1A SAR images (track=131, descending, dates= 2018-11-22 and 2018-12-04), distributed by European Space Agency (ESA), for Interferometric Synthetic Aperture Radar (InSAR) solutions. We constructed unwrapped/wrapped InSAR phase and deformations images by using SNAP software distributed by ESA. We followed the data processing steps of co-registration with enhanced spectral diversity, interferogram generation, deburst, topographic phase removal, Goldstein phase filtering, multilooking and phase unwrapping. We used the GETASSE30 DEM to remove topographic effect on the phase image. Goldstein Filter was run to reduce the noise. To increase the signal-to-noise ratio (S/N), multi-looking was also applied on filtered images by assigning the range and azimuth numbers to 10 and 3, respectively. We then generated a line-of-sight (LOS) vertical displacement image by using SNAPHU (Statistical-Cost, Network-Flow Algorithm for Phase Unwrapping) software distributed by Stanford University , which is a two-dimensional phase unwrapping algorithm essential for surface deformation studies. Our LOS vertical deformation analysis shows a 50 to 60mm vertical downward displacements in the main aftershock distribution area. These results are also consistent with the real-time GPS (vertical component) measurement about 60mm downward displacements measured in the aftershock area.

Presenting Author: Recep Cakir

Authors