Searching for a paleotsunami record in the Hawaiian Islands
Abstract
Historical records of tsunamis over the last 200 years in the state of Hawai'i demonstrate that earthquakes in subduction zones around the Pacific (Aleutian, Kuril-Kamchatka, Chile, Japan, and Alaska) can cause significant tsunami inundation on multiple Hawaiian islands. Deposits found along these subduction zones provide evidence for older tsunamis, but it is unclear if any of these prehistoric far-field events have impacted the Hawaiian islands because no study has successfully correlated Hawaiian paleotsunami deposits between sites or islands. We cored coastal marshlands on Óahu, Maui, and Kauái searching for tsunami deposits in order to determine the viability of extending the record of tsunami inundation in the state of Hawai'i. Sites were selected based on historical tsunami runup, numerical inundation modeling results, the presence of a coastal marsh in close proximity to a sandy shoreline, the extent of undisturbed wetlands, and the breadth of prior geological investigations. Several possible tsunami deposits were identified on the north and northeast shores of Kauái and Óahu as marine sand layers within marsh peat or mud. At some sites, the presence of deposits from the 1946 and 1957 Aleutian tsunamis aided identification of the deeper candidate tsunami deposits. Radiocarbon ages of the deeper sand layers suggest deposition around 800-600 cal yr B.P., which may coincide with a tsunami deposit in the eastern Aleutians that was deposited 660-560 cal yr B.P. (Witter et al., 2016). Further dating and analyses of the deposits is needed to determine whether or not deposition was synchronous on O'ahu and Kaua'i and to determine from sedimentological and micropaleontological characteristics that a tsunami formed the deposits.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMNH43A1820L
- Keywords:
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- 3225 Numerical approximations and analysis;
- MATHEMATICAL GEOPHYSICSDE: 4332 Disaster resilience;
- NATURAL HAZARDSDE: 4341 Early warning systems;
- NATURAL HAZARDSDE: 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL