Student: Hannah Shea, Master’s student in Geoscience, University of Iowa
Faculty Advisor: Dr. William Barnhart
InSAR Time-series Analysis of Afterslip from the 2017 Mw 7.3 Sarpol-e Zahab (Darbandikhan) Earthquake
Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing radar approach used to measure Earth surface deformation. Earthquakes and post-earthquake processes cause ground displacement that can be measured by InSAR. My project includes generating and modeling InSAR time-series of aseismic fault slip (afterslip) following the largest recorded earthquake in the Zagros mountain range of Iran in 2017. Laboratory rock mechanic experiments show that aseismic fault slip occurs under specific frictional conditions, so the time-series observations of afterslip provide the opportunity to constrain the frictional properties of faults in this geologic setting. The Zagros Fold and Thrust Belt is the location for many blind earthquakes which make fault geometries difficult to constrain, so modeling the spatial and temporal extent of afterslip clarifies ambiguity regarding the crystalline basement fault (classified as a “ramp”) and the basal decollement (recognized as a “flat”) where the earthquake and afterslip occurred. The InSAR time-series of afterslip provides a means to estimate frictional mechanics of the ramp and flat, both of which are locations for damaging earthquakes. This project is meant to better our understanding of thick-skin deformation in its entirety, while estimating the frictional properties and large thrusting in the Zagros Mountains, which helps us to greater comprehend earthquake hazard.