Rupture Imaging of Firn Quakes with Distributed Acoustic Sensing
A firn quake is an unusual seismic event resembling an earthquake but occuring in the snowfields and often accompanied by an audible “whumpf” sound. This intriguing phenomenon is explained to be caused by the collapse of a weak snow layer. However, historic reports and quantitative measurements of firn quakes are limited. Here, we report the most distinct firn quakes ever recorded, with their seismic signals clearly captured by a distributed acoustic sensing (DAS) array near the South Pole. The DAS array, deployed in January 2023, extends about ~8 kilometers from the South Pole station to the QSPA seismograph site and consists of ~8,000 channels. The firn quakes, induced during seismic surveys, were both felt directly during the fieldwork and recognized on the DAS records. The seismic records of firn quakes show distinct surface waves with multiple Rayleigh modes generated by the propagating source, with rupture durations varying from a few seconds to about 15 seconds. To investigate the kinematic features of firn quakes, we develop a novel back-projection rupture imaging method, utilizing Rayleigh waves together with an iterative mode striping technique. Our method yields an accurate estimation of rupture speed, depth, and magnitude, which provides critical insights into the physical mechanism of firn quakes.
Session: Advancing Seismology with Distributed Fiber Optic Sensing - I
Type: Oral
Room: K’enakatnu 6
Date: 5/3/2024
Presentation Time: 09:00 AM (local time)
Presenting Author: Jiaxuan Li
Student Presenter: No
Additional Authors
Jiaxuan Li Presenting Author Corresponding Author jxli@caltech.edu California Institute of Technology |
Yan Yang yanyang@caltech.edu California Institute of Technology |
Ettore Biondi ebiondi@caltech.edu California Institute of Technology |
Auden Reid-McLaughlin areidmcl@caltech.edu California Institute of Technology |
Richard Aster rick.aster@colostate.edu Colorado State University |
Douglas Wiens doug@wustl.edu Washington University in St. Louis |
Martin Karrenbach martinkarrenbach@gmail.com Seismic Unusual, LLC |
Zhongwen Zhan zwzhan@caltech.edu California Institute of Technology |
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Rupture Imaging of Firn Quakes with Distributed Acoustic Sensing
Category
Advancing Seismology with Distributed Fiber Optic Sensing
Description