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Synthetic evaluation of infrasonic multipole waveform inversion

December 27, 2021

Acoustic source inversions estimate the mass flow rate of volcanic explosions or yield of chemical explosions and provide insight into potential source directionality. However, the limitations of applying these methods to complex sources and their ability to resolve a stable solution have not been investigated in detail. We perform synthetic infrasound waveform inversions that use 3-D Green’s functions for a variety of idealized and realistic deployment scenarios using both a flat plane and Yasur volcano, Vanuatu as examples. We investigate the ability of various scenarios to retrieve the input source functions and relative amplitudes for monopole and multipole (monopole and dipole) inversions. Infrasound waveform inversions appear to be a robust method to quantify mass flow rates from simple sources (monopole) using deployments of infrasound sensors placed around a source, but care should be taken when analyzing and interpreting results from more complex acoustic sources (multipole) that have significant directional components. In the examples we consider the solution is stable for monopole inversions with a signal-to-noise ratio greater than five and the dipole component is small. For most scenarios investigated, the vertical dipole component of the multipole explosion source is poorly constrained and can impact the ability to recover the other source term components. Because multipole inversions are ill-posed for many deployments, a low residual does not necessarily mean the proper source vector has been recovered. Synthetic studies can help investigate the limitations and place bounds on information that may be missing using monopole and multipole inversions for potentially directional sources.

Publication Year 2022
Title Synthetic evaluation of infrasonic multipole waveform inversion
DOI 10.1029/2021JB023223
Authors Alexandra M. Iezzi, Robin S Matoza, David Fee, Keehoon Kim, Arthur Din Jolly
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research-Solid Earth
Index ID 70240811
Record Source USGS Publications Warehouse
USGS Organization Volcano Science Center