Title: Local Explosion Detection and Infrasound Localization by Reverse Time Migration Using 3-D Finite-Difference Wave Propagation

Abstract

Infrasound data are routinely used to detect and locate volcanic and other explosions, using both arrays and single sensor networks. However, at local distances (< km) topography often complicates acoustic propagation, resulting in inaccurate acoustic travel times leading to biased source locations when assuming straight-line propagation. Here we present a new method, termed Reverse Time Migration-Finite-Difference Time Domain (RTM-FDTD), that integrates numerical modeling into the standard RTM back-projection process. Travel time information is computed across the entire potential source grid via FDTD modeling to incorporate the effects of topography. The waveforms are then back-projected and stacked at each grid point, with the stack maximum corresponding to the likely source. We apply our method to three volcanoes with different network configurations, source-receiver distances, and topography. At Yasur Volcano, Vanuatu, RTM-FDTD locates explosions within ~20 m of the source and differentiates between multiple vents. RTM-FDTD produces a more accurate location for the two Yasur subcraters than standard RTM and doubles the number of detected events. At Sakurajima Volcano, Japan, RTM-FDTD locates the source within 50 m of the active vent despite notable topographic blocking. The RTM-FDTD location is similar to that from the Time Reversal Mirror method, but is more computationally efficient. Lastly, at Shishaldinmore » Volcano, Alaska, RTM and RTM-FDTD both produce realistic source locations (<50 m) for ground-coupled airwaves recorded on a four-station seismic network. We show that RTM is an effective method to detect and locate infrasonic sources across a variety of scenarios, and by integrating numerical modeling, RTM-FDTD produces more accurate source locations and increases the detection capability.« less

Authors:

Fee, David ^[1]; Toney, Liam ^[1]; Kim, Keehoon ^[2]; Sanderson, Richard W. ^[3]; Iezzi, Alexandra M. ^[4]; Matoza, Robin S. ^[3]; De Angelis, Silvio ^[5]; Jolly, Arthur D. ^[6]; Lyons, John J. ^[7]; Haney, Matthew M. ^[7]

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+ Show Author Affiliations

1. Univ. of Alaska, Fairbanks, AK (United States)
2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
3. Univ. of California, Santa Barbara, CA (United States)
4. Univ. of Alaska, Fairbanks, AK (United States); Univ. of California, Santa Barbara, CA (United States)
5. Univ. of Liverpool (United Kingdom)
6. GNS Science, Lower Hutt (New Zealand)
7. US Geological Survey, Anchorage, AK (United States)

Publication Date:

Wed Feb 24 00:00:00 EST 2021

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)

OSTI Identifier:

1804857

Report Number(s):

LLNL-JRNL-823967
Journal ID: ISSN 2296-6463; 1037190

Grant/Contract Number:  

AC52-07NA27344; EAR-1614323; EAR-1614855; EAR-1847736

Resource Type:

Accepted Manuscript

Journal Name:

Frontiers in Earth Science

Additional Journal Information:

Journal Volume: 9; Journal ID: ISSN 2296-6463

Publisher:

Frontiers Research Foundation

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; infrasound; location; explosion; volcano; ground-coupled airwaves; numerical modeling