Frequency dispersion amplifies tsunamis caused by outer-rise normal faults

Abstract Although tsunamis are dispersive water waves, hazard maps for earthquake-generated tsunamis neglect dispersive effects because the spatial dimensions of tsunamis are much greater than the water depth, and dispersive effects are generally small. Furthermore, calculations that include non-dis...

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Autores principales:	Toshitaka Baba, Naotaka Chikasada, Kentaro Imai, Yuichiro Tanioka, Shuichi Kodaira
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/039720aba08f46288a25d0d4526aa505
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spelling	oai:doaj.org-article:039720aba08f46288a25d0d4526aa5052021-12-02T19:16:15ZFrequency dispersion amplifies tsunamis caused by outer-rise normal faults10.1038/s41598-021-99536-x2045-2322https://doaj.org/article/039720aba08f46288a25d0d4526aa5052021-10-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-99536-xhttps://doaj.org/toc/2045-2322Abstract Although tsunamis are dispersive water waves, hazard maps for earthquake-generated tsunamis neglect dispersive effects because the spatial dimensions of tsunamis are much greater than the water depth, and dispersive effects are generally small. Furthermore, calculations that include non-dispersive effects tend to predict higher tsunamis than ones that include dispersive effects. Although non-dispersive models may overestimate the tsunami height, this conservative approach is acceptable in disaster management, where the goal is to save lives and protect property. However, we demonstrate that offshore frequency dispersion amplifies tsunamis caused by outer-rise earthquakes, which displace the ocean bottom downward in a narrow area, generating a dispersive short-wavelength and pulling-dominant (water withdrawn) tsunami. We compared observational evidence and calculations of tsunami for a 1933 M w 8.3 outer-rise earthquake along the Japan Trench. Dispersive (Boussinesq) calculations predicted significant frequency dispersion in the 1933 tsunami. The dispersive tsunami deformation offshore produced tsunami inundation heights that were about 10% larger than those predicted by non-dispersive (long-wave) calculations. The dispersive tsunami calculations simulated the observed tsunami inundation heights better than did the non-dispersive tsunami calculations. Contrary to conventional practice, we conclude that dispersive calculations are essential when preparing deterministic hazard maps for outer-rise tsunamis.Toshitaka BabaNaotaka ChikasadaKentaro ImaiYuichiro TaniokaShuichi KodairaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-11 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Toshitaka Baba Naotaka Chikasada Kentaro Imai Yuichiro Tanioka Shuichi Kodaira Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
description	Abstract Although tsunamis are dispersive water waves, hazard maps for earthquake-generated tsunamis neglect dispersive effects because the spatial dimensions of tsunamis are much greater than the water depth, and dispersive effects are generally small. Furthermore, calculations that include non-dispersive effects tend to predict higher tsunamis than ones that include dispersive effects. Although non-dispersive models may overestimate the tsunami height, this conservative approach is acceptable in disaster management, where the goal is to save lives and protect property. However, we demonstrate that offshore frequency dispersion amplifies tsunamis caused by outer-rise earthquakes, which displace the ocean bottom downward in a narrow area, generating a dispersive short-wavelength and pulling-dominant (water withdrawn) tsunami. We compared observational evidence and calculations of tsunami for a 1933 M w 8.3 outer-rise earthquake along the Japan Trench. Dispersive (Boussinesq) calculations predicted significant frequency dispersion in the 1933 tsunami. The dispersive tsunami deformation offshore produced tsunami inundation heights that were about 10% larger than those predicted by non-dispersive (long-wave) calculations. The dispersive tsunami calculations simulated the observed tsunami inundation heights better than did the non-dispersive tsunami calculations. Contrary to conventional practice, we conclude that dispersive calculations are essential when preparing deterministic hazard maps for outer-rise tsunamis.
format	article
author	Toshitaka Baba Naotaka Chikasada Kentaro Imai Yuichiro Tanioka Shuichi Kodaira
author_facet	Toshitaka Baba Naotaka Chikasada Kentaro Imai Yuichiro Tanioka Shuichi Kodaira
author_sort	Toshitaka Baba
title	Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
title_short	Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
title_full	Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
title_fullStr	Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
title_full_unstemmed	Frequency dispersion amplifies tsunamis caused by outer-rise normal faults
title_sort	frequency dispersion amplifies tsunamis caused by outer-rise normal faults
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/039720aba08f46288a25d0d4526aa505
work_keys_str_mv	AT toshitakababa frequencydispersionamplifiestsunamiscausedbyouterrisenormalfaults AT naotakachikasada frequencydispersionamplifiestsunamiscausedbyouterrisenormalfaults AT kentaroimai frequencydispersionamplifiestsunamiscausedbyouterrisenormalfaults AT yuichirotanioka frequencydispersionamplifiestsunamiscausedbyouterrisenormalfaults AT shuichikodaira frequencydispersionamplifiestsunamiscausedbyouterrisenormalfaults
_version_	1718376952158486528

Frequency dispersion amplifies tsunamis caused by outer-rise normal faults

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