Seismic Characterization of the Explosive Subevents in the 2022 Hunga-Tonga Volcanic Eruption Using Joint Moment Tensor Inversion
The Hunga-Tonga submarine volcanic eruption of January 15, 2022, was notable for its size and effects on the atmosphere, including the generation of sound waves. In this work, we are interested in the seismic signal from this event, which was recorded by global seismic stations and lasted approximately 20 minutes, with the largest subevents occurring over a 5-minute period starting at 04:15:17 UTC. Our previous study identified four subevents and a predominantly explosive source mechanism in the associated seismic activity. However, it relied on a hypothesis that each subevent had an identical source mechanism. In this study, we analyzed waveform data from regional surface waves filtered between 25 and 70 seconds and used a computational approach to estimate a set of parameters that best fit the data and allowed a different source mechanism and onset time to be estimated for each subevent. The analysis was conducted using the Covariance Matrix Adaptation Evolution Strategy (CMA-ES), which allowed us to design a scalable inversion scheme required to increase unknown parameters (28 in total). Our results indicate that all subevents had explosive source mechanisms, as indicated by all-positive eigenvalues of the subevent moment tensors. The combined magnitude of the four subevents ranged from 6.35 to 6.71 Mw, highlighting the difficulty of precisely defining the source magnitude with the set of available regional data. These findings suggest that the subevents were similar in nature and may aid in understanding the overall sequence of the eruption. Due to the stochastic nature of the CMA-ES algorithm, we validated our findings by producing ten independent parameter searches of the model space.
Session: Exploiting Explosion Sources: Advancements in Seismic Source Physics
Type: Oral
Room: 203
Date: 4/19/2023
Presentation Time: 04:45 PM (local time)
Presenting Author: Julien Thurin
Student Presenter: No
Additional Authors
Julien Thurin Presenting Author Corresponding Author jthurin@alaska.edu University of Alaska Fairbanks |
Carl Tape ctape@alaska.edu University of Alaska Fairbanks |
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Seismic Characterization of the Explosive Subevents in the 2022 Hunga-Tonga Volcanic Eruption Using Joint Moment Tensor Inversion
Category
Exploiting Explosion Sources: Advancements in Seismic Source Physics
Description