Block and boulder transport in Eastern Samar (Philippines) during Supertyphoon Haiyan
Fields of dislodged boulders and blocks record catastrophic coastal flooding during strong storms or tsunamis and play a pivotal role in coastal hazard assessment. Along the rocky carbonate coast of Eastern Samar (Philippines) we documented longshore transport of a block of 180 t and boulders (up to...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-12-01
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| Series: | Earth Surface Dynamics |
| Online Access: | http://www.earth-surf-dynam.net/3/543/2015/esurf-3-543-2015.pdf |
| Summary: | Fields of dislodged boulders and blocks record catastrophic coastal flooding
during strong storms or tsunamis and play a pivotal role in coastal hazard
assessment. Along the rocky carbonate coast of Eastern Samar (Philippines)
we documented longshore transport of a block of 180 t and boulders (up to
23.5 t) shifted upslope to elevations of up to 10 m above mean lower low
water level during Supertyphoon Haiyan on 8 November 2013. Initiation-of-motion
approaches indicate that boulder dislocation occurred with flow velocities
of 8.9–9.6 m s<sup>−1</sup>, which significantly exceeds depth-averaged flow velocities
of a local coupled hydrodynamic and wave model (Delft3D) of the typhoon with
a maximum < 1.5 m s<sup>−1</sup>. These results, in combination with recently
published phase-resolving wave models, support the hypothesis that
infragravity waves induced by the typhoon were responsible for the
remarkable flooding pattern in Eastern Samar, which are not resolved in
phase-averaged storm surge models. Our findings show that tsunamis and
hydrodynamic conditions induced by tropical cyclones may shift boulders of
similar size and, therefore, demand a careful re-evaluation of storm-related
transport where it, based on the boulder's sheer size, has previously been
ascribed to tsunamis. |
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| ISSN: | 2196-6311 2196-632X |