Infrasound from the repeated collapses of Kilauea caldera: High-resolution source location and waveform inversion
Abstract
Kilauea caldera has undergone drastic changes during the 2018 Lower East Rift Zone eruption due to the coincident withdrawal of magma in the summit region. This withdrawal has caused significant subsidence focused around Halema`uma`u crater due to both gradual slumping and discrete near-daily collapse events. To examine these collapse events, we had 3-7 campaign infrasound sensors deployed 1.5-4 km from Halema`uma`u crater with good azimuthal coverage to complement the permanent infrasound array (AHUD) 4 km away. The collapse events have produced remarkably similar waveforms since the onset of broader caldera subsidence in late May. Co-seismic shaking dominates the infrasound onsets and at frequencies above 1 Hz. The majority of the acoustic energy is at very long periods focused around 15 s, with peak amplitudes around 10 Pa at 1.5 km. Unlike most volcano infrasound signals, these infrasonic VLP's begin with a rarefaction (decrease in pressure), likely coincident with rapid collapse of Halema`uma`u crater and/or collapse of the magma storage system beneath it. This is somewhat unexpected as the co-collapse geodetic signal is inflationary. Here we apply infrasound source location and waveform inversion techniques to locate the areas of most rapid subsidence and determine the total collapse volume for each event. Both techniques use high-resolution digital elevation models (DEMs) and finite difference time domain (FDTD) modeling to account for acoustic wave propagation. We compare the infrasound-derived volume fluxes with those from geodetic inversions and high-resolution DEMs, providing an opportunity to validate multiple inversion techniques. The infrasound from the Kilauea caldera collapse events provides a unique look into the rate, style, evolution, and volume flux of this rarely observed volcanic process.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V41B..04F
- Keywords:
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- 8499 General or miscellaneous;
- VOLCANOLOGY