A wave-competence approach to distinguish between boulder and megaclast deposits due to storm waves versus tsunamis

Lorang, Mark S.

doi:10.1016/j.margeo.2010.10.005

Cited by 68 publications

(43 citation statements)

References 41 publications

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“…For example, applying Eq. (1) of Lorang [2011] to the conditions at Calicoan Island leads to estimates of 1-2 m final elevation for a 2 m diameter boulder, which is far less than was observed. The present work demonstrates that the potential to transport large boulders far onshore to high inland elevations does not lie exclusively with tsunamis, but can also be achieved by strong tropical cyclones.…”

Section: Discussionmentioning

confidence: 69%

“…The transport of coastal boulders by storm waves and tsunamis has been a topic of considerable discussion in the recent literature [Nott, 2003;Fichaut and Suanez, 2011;Lorang, 2011;Engel and May, 2012;Bourgeois and MacInnes, 2010]. In large part, the motivation for these boulder transport studies has been to estimate the magnitude of past events for which no other records exist [Nott, 2003;, and to evaluate implications for present day disaster reduction planning.…”

Section: Introductionmentioning

confidence: 99%

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Observations and Modeling of Coastal Boulder Transport and Loading During Super Typhoon Haiyan

Kennedy

Mori

Zhang

et al. 2016

Coastal Engineering Journal

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Boulders numbering in the high hundreds/low thousands, and with masses up to ∼ 30 tonnes, were transported onshore by Super Typhoon Haiyan in Calicoan Island, Philippines to maximum ground elevations that could exceed 9 m and terminal positions up to ∼ 180 m inland. One-dimensional Boussinesq hindcasts of coastal boulder motion showed intermittent transport initiated at the fronts of infragravity swash bores. Transport distances were found to be highly sensitive to wave-height, enough so that observations of terminal positions may be a viable method of estimating rough paleostorm magnitudes. The large accelerations at bore fronts generated significant inertial forces, particularly for larger boulders, but drag forces had greater root-mean-square magnitudes in all simulations. Widely used relations to infer fluid velocities from boulder properties were tested using modeled boulders -inferred velocities at modeled terminal boulder positions were compared to maximum computed Boussinesq fluid velocities at these locations and found A. B. Kennedy et al.to be significantly lower. This underprediction of inferred velocities was greatest for smaller boulders that were strongly mobile. Inferred drag loads compared to modeled values were somewhat more accurate for large boulders when a Froude number of unity was assumed to estimate flow depths. Although these boulders were unequivocally transported by storm waves, their large sizes and distances traveled venture into what has been considered the tsunami range. Thus, care must be taken to interpret the provenance of coastal boulder fields with unknown origin for lower to mid-latitude regions.

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Section: Discussionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

Observations and Modeling of Coastal Boulder Transport and Loading During Super Typhoon Haiyan

Kennedy

Mori

Zhang

et al. 2016

Coastal Engineering Journal

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“…Criteria to distinguish between tsunamis and storms include exponential landward fining of boulder fields or the generation of ridges due to strong storms, as well as more random scattering of boulders through tsunamis (Goto et al, 2010;Richmond et al, 2011). For some boulder deposits, storm transport was ruled out based on their large size, elevation and distance from the coast, and local extreme storm wave conditions (Scicchitano et al, 2007;Engel and May, 2012), while the long wave period of tsunamis has been associated with a higher transport competence (Lorang, 2011). However, the topic is still a matter of considerable debate (Goto et al, 2010;Lorang, 2011); until recently, only few studies provided unambiguous evidence for the transport of very large clasts during storms (Goto et al, 2011), e.g.…”

Section: Introductionmentioning

confidence: 99%

“…For some boulder deposits, storm transport was ruled out based on their large size, elevation and distance from the coast, and local extreme storm wave conditions (Scicchitano et al, 2007;Engel and May, 2012), while the long wave period of tsunamis has been associated with a higher transport competence (Lorang, 2011). However, the topic is still a matter of considerable debate (Goto et al, 2010;Lorang, 2011); until recently, only few studies provided unambiguous evidence for the transport of very large clasts during storms (Goto et al, 2011), e.g. based on direct observations, reliable historical documentation, or satellite data (Table 1).…”

Section: Introductionmentioning

confidence: 99%

Block and boulder transport in Eastern Samar (Philippines) during Supertyphoon Haiyan

May¹,

Engel²,

Brill³

et al. 2015

Earth Surf. Dynam.

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Abstract. 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 −1 , 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 −1 . 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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“…The differentiation of tsunami deposits from tempestites has been widely discussed for deposits left on land (e.g., Nott, 2003;Goff et al, 2004;Kortekaas and Dawson, 2007;Morton et al, 2007;Switzer and Jones, 2008;Lario et al, 2010;Lorang, 2011;Richmond et al, 2011;Phantuwongraj and Choowong, 2012;Ramírez-Herrera et al, 2012;Brill et al, 2014a). However, there is no consensus yet on reliable sedimentological criteria to distinguish between offshore storm and tsunami deposits.…”

Section: Introductionmentioning

confidence: 99%

Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash-flood deposits

Sakuna-Schwartz

Feldens

Schwarzer

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Tsunami, storm and flash-flood event layers, which have been deposited over the last century on the shelf offshore Khao Lak (Thailand, Andaman Sea), are identified in sediment cores based on sedimentary structures, grain size compositions, Ti / Ca ratios and 210 Pb activity. Individual offshore tsunami deposits are 12 to 30 cm in thickness and originate from the 2004 Indian Ocean Tsunami. They are characterized by (1) the appearance of sand layers enriched in shells and shell debris and (2) the appearance of mud and sand clasts. Storm deposits found in core depths between 5 and 82 cm could be attributed to recent storm events by using 210 Pb profiles in conjunction with historical data of typhoons and tropical storms. Massive sand layers enriched in shells and shell debris characterize storm deposits. The last classified type of event layer represents reworked flash-flood deposits, which are characterized by a fining-upward sequence of muddy sediment. The most distinct difference between storm and tsunami deposits is the lack of mud and sand clasts, mud content and terrigenous material within storm deposits. Terrigenous material transported offshore during the tsunami backwash is therefore an important indicator to distinguish between storm and tsunami deposits in offshore environments.

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A wave-competence approach to distinguish between boulder and megaclast deposits due to storm waves versus tsunamis

Cited by 68 publications

References 41 publications

Observations and Modeling of Coastal Boulder Transport and Loading During Super Typhoon Haiyan

Observations and Modeling of Coastal Boulder Transport and Loading During Super Typhoon Haiyan

Block and boulder transport in Eastern Samar (Philippines) during Supertyphoon Haiyan

Internal structure of event layers preserved on the Andaman Sea continental shelf, Thailand: tsunami vs. storm and flash-flood deposits

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