Tidally Modulated Icequakes Along a Ross Ice Shelf Rift in Antarctica
Description:
The Ross Ice Shelf (RIS) in Antarctica is the largest ice shelf on Earth. There are multiple periodically spaced rifts spanning ~100 km. They were formed due to a buildup of tensile stress as the ice shelf flows toward the Ross Sea. Previous work established that these rifts are seismically active, with seismicity modulated by tidal stresses. Here we present high quality seismic results from the NASA-supported Antarctic Rift Research for Ocean Worlds (ARROW) project which deployed 16 seismometers and 12 GPS stations across the east portion of the rift Western Ross 4 (WR4) between December 2022 and January 2023. The ARROW array recorded over 6000 seismic events (i.e. icequakes) and measured surface strain across WR4 from the GPS data. To locate the icequakes, we first hand-picked the P- and S-wave arrivals from each seismic station of an event. We then used a layered velocity structure derived from the active source experiments to locate each icequake and their depth. For events with higher signal-to-noise ratio, we additionally computed their moment tensor solutions. Our results indicate that most icequakes were located along both sides of the WR4 rift, and their distribution appears to represent several major en echelon fractures that can be observed from optical satellite imagery. Additionally, ~73% of the icequakes occurred during the extensional phase of the strain rates. For the moment tensor solutions, the Variance Reduction (VR) of most events are greater than 20% with their major tension-axis nearly parallel to the main ice flow direction. About 80% icequakes are located at a shallow depth (≤ 50 m), and 40% of them are shallower than 20 m depth, implying events occur within the shallow mélange within the rift or shallow marginal crevasses. Our measurements of deformation across the WR4 rift provide new constraints on the material strength and properties of both the ice shelf and rift mélange. Our results have implications for the ongoing deformation of ice shelf structures which affect the stability of the RIS in the future under a changing climate.
Session: Unusual Earthquakes and Their Implications [Poster]
Type: Poster
Date: 4/16/2025
Presentation Time: 08:00 AM (local time)
Presenting Author: Kathrine
Student Presenter: Yes
Invited Presentation:
Poster Number: 18
Authors
Kathrine Udell-Lopez Presenting Author kudell@umd.edu University of Maryland, College Park |
Mong-Han Huang Corresponding Author mhhuang@umd.edu University of Maryland, College Park |
Zoe Schlossnagle zschloss@terpmail.umd.edu University of Maryland, College Park |
Nicholas Schmerr nschmerr@umd.edu University of Maryland, College Park |
Emily Harkleroad eharkle1@terpmail.umd.edu University of Maryland, College Park |
Simon Eisl simonruns6@gmail.com University or New Hampshire |
Terry Hurford terry.a.hurford@nasa.gov NASA |
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Tidally Modulated Icequakes Along a Ross Ice Shelf Rift in Antarctica
Session
Unusual Earthquakes and Their Implications