SCEC Award Number 21019 View PDF
Proposal Category Collaborative Proposal (Integration and Theory)
Proposal Title Modeling of postseismic deformation following the 2019 Ridgecrest earthquake sequence
Investigator(s)
Name Organization
Roland Bürgmann University of California, Berkeley Eric Fielding National Aeronautics and Space Administration Kang Wang University of California, Berkeley Zhen Liu National Aeronautics and Space Administration
Other Participants Niloufar Abolfathian, NASA Postdoctoral Program
SCEC Priorities 1e, 3a, 3b SCEC Groups Geodesy, SDOT, CXM
Report Due Date 03/15/2022 Date Report Submitted 03/15/2022
Project Abstract
 Based on our previous year’s effort, this project aims to characterize the spatial and temporal distributions of postseismic deformation spanning nearly two years after the 2019 Ridgecrest earthquake sequence using Satellite Radar Interferometry (InSAR) of multiple SAR satellites and Global Navigation Satellite Systems (GNSS). The primary goal of this project is to model the underlying postseismic deformation observed during the first two years after the mainshock. Using InSAR and GNSS data collected during the first 2 years after the mainshock, we have developed an initial set of models to characterize the early postseismic deformation following the 2019 Ridgecrest earthquake sequence. We show that the surface deformation 2 years after the 2019 Ridgecrest earthquakes consists of contributions from all three commonly considered relaxation mechanisms, including afterslip, viscoelastic relaxation, and poroelastic rebound. Specifically, the InSAR deformation observed in the near-to-medium field can be well explained by a model combining both afterslip and poroelastic rebound, while the GNSS displacements in the far-field require the involvement of viscoelastic relaxation from the upper mantle. This is important not only for understanding how strain and stress evolve, but also for evaluating the impact of the 2019 earthquakes on the surface deformation field represented by SCEC’s Community Geodetic Model (CGM), both in the near field of the rupture and across southern California.
Intellectual Merit This project characterizes the spatial and temporal distributions of postseismic deformation following the 2019 Ridgecrest earthquake sequence in southern California, which directly contributes to establishing the Community Geodetic Model and crustal deformation in southern California. Postseismic deformation models derived in this effort are of great importance to sharpen our understanding of the stress evolution after a large earthquake, and constrain the rheological properties of the fault zone and surrounding rocks. The InSAR LOS velocity and displacement time series developed in this study complement the contributions of several other CGM groups focusing on the C-band Sentinel-1 InSAR data. The methods of correcting for the InSAR atmospheric noise developed in this study are also helpful to better utilize and interpret the InSAR data of other SAR missions, such as the ALOS-2 and the planned NISAR mission.
Broader Impacts This project supported the intellectual development of a postdoc Kang Wang. Kang was supported to present his work at the 2021 SCEC annual meeting the AGU fall meeting and interact with other members of the SCEC community. A research article summarizing the effort of this project is currently under preparation. The postseismic deformation data and models developed in this project can be integrated as part of the CGM, which will benefit a broader community.
Exemplary Figure Figure 2. Distribution of cumulative afterslip ~1.5 years after the 2019 Ridgecrest earthquake sequence. Grey dots in panels to the right represent the aftershocks during ~2 weeks after the mainshock (Shelly, 2020). Blue contours represent the coseismic slip contours at 1-meter interval (from Wang et al., 2020). The red star represents the hypocenter of the mainshock. Green star denotes the approximate location of the Mw 5.5 aftershock on 06/30/2020.