Radial Backprojection Imaging of Recent Mass Movements in Alaska
Description:
Backprojection imaging has shown utility for locating seismic events using waveform data, without requiring timing information from clear phase arrivals. Processes imaged with backprojection include earthquake rupture, volcanic tremor, and surficial mass movements. Here we develop a novel backprojection method using the radial horizontal component, instead of the conventional technique utilizing the vertical component, and apply it to recent mass movements in Alaska. Use of the radial horizontal component is designed to image the source region with Rayleigh waves, which are efficiently generated by surficial seismic sources. Although radial backprojection offers many advantages to vertical backprojection, including improved signal-to-noise ratio (SNR) of the image and the ability to image the source location with only two stations, its application requires additional details in order to quantitatively interpret the normalized amplitude of the backprojection image. For vertical backprojection, a normalized amplitude between 0 and 1 indicates either perfectly destructive (0) or perfectly constructive (1) stacking of the vertical waveforms at different stations. In contrast, a normalized amplitude of 1 for radial component backprojection indicates perfectly constructive stacking of signals exhibiting exclusively radial particle motion (i.e., no transverse component). We apply this novel radial backprojection method to a glacial calving event at Barry Arm on December 15, 2022, a landslide on the Kenai Peninsula near Seward on September 15, 2022, and a large ice-rock avalanche at Iliamna volcano on June 21, 2019. These case studies demonstrate the ability of radial backprojection to locate a source with as few as two stations and the improved SNR of the radial backprojection image compared to vertical backprojection. We also discuss the similarities and differences between radial backprojection and the method known as radial semblance developed by Kawakatsu et al. (2000; JVGR) and Almendros and Chouet (2003; BSSA).
Session: Detecting, Characterizing and Monitoring Mass Movements - II
Type: Oral
Date: 5/2/2024
Presentation Time: 11:15 AM (local time)
Presenting Author: Matthew
Student Presenter: No
Invited Presentation:
Authors
Matthew Haney Presenting Author Corresponding Author mhaney@usgs.gov U.S. Geological Survey |
Liam Toney ltoney@usgs.gov U.S. Geological Survey |
Ezgi Karasozen ekarasozen@alaska.edu University of Alaska Fairbanks |
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Radial Backprojection Imaging of Recent Mass Movements in Alaska
Category
Detecting, Characterizing and Monitoring Mass Movements