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Source Study of Ice-quakes in a Ross Ice Shelf Rift

Description: 

Building upon prior research that documented thousands of icequakes at Ross Ice Shelf Rift WR4 using nine broadband seismic stations—events linked to tidal cycles, thermal stress, and temperature variations (Olinger et al., 2019; Huang et al., 2022)—we apply moment tensor inversion techniques to better understand generation mechanisms for icequake and ice deformation dynamics. We conduct full-moment-tensor analyses using the Computer Programs in Seismology (CPS) package, computing Green's functions for a layered subsurface model consisting of surface firn, underlying ice, water, sediment, and crystalline basement rock. Our analysis identifies distinct extensional Lamb-wave signals propagating at velocities of 2.7–3.2 km/s that are successfully modeled by synthetic seismograms. To account for uncertainties in cataloged events, we perform inversions across a grid around each source and identify optimal centroid locations and origin times. Our findings indicate that all centroid depths occur in the upper 40 meters within the firn layer, demonstrating that failure occurs in the shallow brittle layer. The moment tensor solutions suggest a combination of crack opening, one crack collapse, and a DC component oriented in the direction of the WR4 rift, and moment magnitude vary between 0.4 and 1.5. The calculated extensional stress based on the CATS2008_v2023 tidal model shows a stretching stress of 0.3–0.8 kPa at the time of icequakes due to tidally induced tilting of the ice shelf, while the stress for the event with a crack-closing solution falls below 0.2 kPa. These findings provide quantitative constraints on ice shelf rifting dynamics and insights for assessing Antarctic ice sheet stability under evolving environmental conditions.

Session: Cryoseismology: Advances in Technology and Scientific Discovery [Poster]

Type: Poster

Date: 4/15/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Farzaneh Aziz Zanjani

Student Presenter: No

Invited Presentation: 

Poster Number: 1

Authors