A COMPARATIVE STUDY OF THE TSUNAMIS FROM THE 2021 AND 2023 LOYALTY ISLANDS Mw 7.7 THRUST-FAULT AND NORMAL-FAULT EARTHQUAKES

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dc.contributor.advisorCheung, Kwok F.
dc.contributor.authorRobert, William Henry
dc.contributor.departmentOcean & Resources Engineering
dc.date.accessioned2024-10-09T23:45:54Z
dc.date.available2024-10-09T23:45:54Z
dc.date.issued2024
dc.description.degreeM.S.
dc.identifier.urihttps://hdl.handle.net/10125/108676
dc.subjectOcean engineering
dc.subjectearthquake
dc.subjecttsunami
dc.titleA COMPARATIVE STUDY OF THE TSUNAMIS FROM THE 2021 AND 2023 LOYALTY ISLANDS Mw 7.7 THRUST-FAULT AND NORMAL-FAULT EARTHQUAKES
dc.typeThesis
dcterms.abstractThe Vanuatu Subduction Zone, which runs along the San Cristobal Trench and New Hebrides Trench, is an active tectonic region with a history of moderate to large tsunamigenic earthquakes. While over 40 earthquakes of Mw 7.0 or stronger have occurred along the New Hebrides trench within the past quarter-century, the subduction dynamics, tsunamigenic potential, and coastal risk of tsunamigenic earthquakes emanating from the southern trench remain understudied. We compare the tsunami signals from the 2021 and 2023 Mw 7.7 thrust-fault and normal-fault earthquakes along the South New Hebrides Trench. The 2021 megathrust earthquake was determined to have a relatively shallow slip patch with a focal depth of 10.0 km. The 2023 outer-rise normal-faulting earthquake occurred westward of the 2021 event at a depth of 18.1 km. The comparable moment magnitude and proximity of their epicenters provide an opportunity to examine the influence of fault mechanisms and bathymetric features at the Southern New Hebrides Trench on the tsunami waveform throughout the Southwest Pacific. The preferred finite-fault rupture models for each earthquake event were determined through iterative inversion of teleseismic P-waves and forward modeling of the tsunami waveform to match measurements at DART and coastal tide gauge stations. Analysis of the computed tsunami waveforms reveals that the 2021 and 2023 tsunamis are primarily influenced by the location of the seafloor deformation with respect to major bathymetric features in the near-field. The width of seafloor deformation and source water depth influence the subsequent period of tsunami waves, which has a strong effect on far-field energy lobes guided by seamounts and small islands, but the overall wave patterns exhibit similarities because the effects of bathymetry and resonance dominate at a larger scale.
dcterms.extent51 pages
dcterms.languageen
dcterms.publisherUniversity of Hawai'i at Manoa
dcterms.rightsAll UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
dcterms.typeText
local.identifier.alturihttp://dissertations.umi.com/hawii:12287

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M.S. - Ocean and Resources Engineering