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| Titel |
Dispersion of tsunamis: does it really matter? |
| VerfasserIn |
S. Glimsdal, G. K. Pedersen, C. B. Harbitz, F. Løvholt |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 6 ; Nr. 13, no. 6 (2013-06-18), S.1507-1526 |
| Datensatznummer |
250018498
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| Publikation (Nr.) |
 copernicus.org/nhess-13-1507-2013.pdf |
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| Zusammenfassung |
| This article focuses on the effect of dispersion in the field of tsunami
modeling. Frequency dispersion in the linear long-wave limit is first briefly
discussed from a theoretical point of view. A single parameter, denoted as
"dispersion time", for the integrated effect of frequency dispersion is
identified. This parameter depends on the wavelength, the water depth during
propagation, and the propagation distance or time. Also the role of long-time
asymptotes is discussed in this context. The wave generation by the two main
tsunami sources, namely earthquakes and landslides, are briefly discussed
with formulas for the surface response to the bottom sources. Dispersive
effects are then exemplified through a semi-idealized study of a
moderate-strength inverse thrust fault. Emphasis is put on the directivity,
the role of the "dispersion time", the significance
of the Boussinesq model employed (dispersive effect), and the effects of the transfer from
bottom sources to initial surface elevation. Finally, the experience from a
series of case studies, including earthquake- and landslide-generated
tsunamis, is presented. The examples are taken from both historical (e.g. the
2011 Japan tsunami and the 2004 Indian Ocean tsunami) and potential tsunamis
(e.g. the tsunami after the potential La Palma volcanic flank collapse).
Attention is mainly given to the role of dispersion during propagation in the
deep ocean and the way the accumulation of this effect relates to the
"dispersion time". It turns out that this parameter is useful as a first
indication as to when frequency dispersion is important, even though
ambiguity with respect to the definition of the wavelength may be a problem
for complex cases.
Tsunamis from most landslides and
moderate earthquakes tend to display dispersive behavior, at least in some
directions. On the other hand, for the mega events of the last decade
dispersion during deep water propagation is mostly noticeable for
transoceanic propagation. |
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