Title: Three–Dimensional Acoustic Multipole Waveform Inversion at Yasur Volcano, Vanuatu

Abstract

Acoustic waveform inversions can provide estimates of volume flow rate and erupted mass, enhancing the ability to estimate volcanic emissions. Previous studies have generally assumed a simple acoustic source (monopole); however, more complex and accurate source reconstructions are possible with a combination of equivalent sources (multipole). We deployed a high–density acoustic network around Yasur volcano, Vanuatu, including acoustic sensors on a tethered aerostat that was moved every ~15–60 min. Using this unique data set we invert for the acoustic multipole source mechanism using a grid search approach for 80 events to examine volume flow rates and dipole strengths. Our method utilizes finite–difference time–domain modeling to obtain the full 3–D Green's functions that account for topography. Inversion results are compared using a monopole–only, multipole (monopole and dipole), simulations that do not include topography, and those that use a subset of sensors. We find that the monopole source is a good approximation when topography is considered. However, initial compression amplitude is not fully captured by a monopole source so source directionality cannot be ruled out. The monopole solution is stable regardless of whether a monopole–only or multipole inversion is performed. Inversions for the dipole components produce estimates consistent with observed source directionality,more » though these inversions are somewhat unstable given station configurations of typical deployments. Furthermore, our results suggest that infrasound waveform inversion shows promise for realistic quantitative source estimates, but additional work is necessary to fully explore inversion stability, uncertainty, and robustness.« less

Authors:

Iezzi, A. M.  ^[1];

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Fee, D.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-0936-9977"
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Kim, K.  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-8635-0428"
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Jolly, A. D.  ^[3];

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• Search DOE PAGES for ORCID "0000-0003-1020-9062"
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Matoza, R. S.  ^[4]

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• Search DOE PAGES for ORCID "0000-0003-4001-061X"
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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. GNS Science, Lower Hutt (New Zealand)
4. Univ. of California, Santa Barbara, CA (United States)

Publication Date:

2019-07-24

Research Org.:

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

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1583041

Report Number(s):

[LLNL-JRNL-800930]
[Journal ID: ISSN 2169-9313; 1004072]

Grant/Contract Number:  

[AC52-07NA27344; EAR-1847736]

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Solid Earth

Additional Journal Information:

[ Journal Volume: 124; Journal Issue: 8]; Journal ID: ISSN 2169-9313

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES