A MPG/SGT seminar presentation Kathrine Udell from the University of Maryland.
Title:
Strength and Seismic Properties of Ross Ice Shelf Ice Rifts Constrained through Joint Seismic and Geodetic Deployments
Abstract:
The Ross Ice Shelf (RIS) located in Antarctica is the Earth’s largest ice shelf. A buildup of tensile stress as the ice shelf flows to the Ross Sea resulted in multiple periodically spaced ice rifts that are ~100km in length. Previous work established that these rifts are seismically active with seismicity modulated with tidally driven stress. Here we utilize joint seismic and geodetic datasets from the 2014-17 Dynamic Response of the Ross Ice Shelf project (DRRIS) deployment and our NASA-funded Antarctic Rift Research for Ocean Worlds (ARROW) deployment in 2022-23 to determine the brittle fracturing properties of two rift zones of the RIS with different material maturities. Using the ARROW data, we produce a high-resolution seismic catalog with more than 6000 icequake events. We determine that seismicity is strongly associated with extensional strain rates based on GPS data. We compare the observed icequake occurrence times with analytical predictions from rate-and-state friction constitutive laws that have been used to model frictional behavior on terrestrial faults. We find that seismicity rate is well predicted by an analytical model based on rate-and-state friction, demonstrating consistent physical properties between crustal material and ice shelves. Further, we find that rift sensitivity to periodic stress is age dependent. Seismic event locations follow fractures visible within these rift zones through mapping of high-resolution Worldview satellite imagery. These environments and datasets provide a unique opportunity to better understand the brittle failure processes for ice beyond laboratory scales, providing important constraints on the future stability of the RIS under varying stress conditions. Finally, insights gained from tidally driven seismicity along these ice shelf rift zones can also serve as analogs for terrestrial faults under periodic stress loading or the response of ice-ocean world ice shells to tidal forcings.
