Effects of fringing reefs on tsunami inundation: American Samoa

Gelfenbaum, Guy; Apotsos, Alex; Stevens, Andrew W.; Jaffe, Bruce E.

doi:10.1016/j.earscirev.2010.12.005

Cited by 82 publications

(63 citation statements)

References 38 publications

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“…They seem to act as efficient natural barriers partially protecting the coasts from wind-wave and cyclonic swell impacts as reported by Clark (1991) and Frihy et al (2004). Several recent studies show that they also play a predominant role in case of tsunami arrival (Kunkel et al, 2006;Fernando et al, 2008;Liu and Ghidaoui, 2009;Baba et al, 2008;Gelfenbaum et al, 2011). Unfortunately, these reefs are highly threatened by human activities, a threat also re-enforced by storms (Wilkinson, 1999;Bouchon et al, 2008a,b) as in 75 % of the world's coral reefs, as reported by Burke et al (2011).…”

Section: Introductionmentioning

confidence: 97%

Tsunami hazard assessment of Guadeloupe Island (F.W.I.) related to a megathrust rupture on the Lesser Antilles subduction interface

Roger

Dudon

Zahibo

2013

Nat. Hazards Earth Syst. Sci.

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The French Caribbean Archipelago of Guadeloupe is located over the Lesser Antilles active subduction zone, where a handful of earthquakes have reached magnitudes of Mw = 7.0 (moment magnitude) and more. According to available catalogs, these earthquakes have been able to trigger devastating tsunamis, either directly by the shake or indirectly by induced landslides. The Guadeloupe Archipelago is known to have suffered from several violent earthquakes, including the 1843 Mw ~ 8.5 megathrust event. In this study, we discuss the potential impact of a tsunami generation scenario of a Mw = 8.5 rupture at the subduction interface using numerical modeling and high resolution bathymetric data within the framework of tsunami hazard assessment for Guadeloupe. Despite the fact that the mystery remains unresolved concerning the lack of historical tsunami data for the 1843 event, modeling results show that the tsunami impact is not uniformly distributed in the whole archipelago and could show important maximum wave heights. This is easily explained by the bathymetry and the presence of several islands around the main island leading to resonance phenomena, and because of the existence of a fringing coral reef partially surrounding Guadeloupe Island and its satellites. We then discuss the role of source parameters, the arrival times and the protective role of fringing coral reefs surrounding the islands, using tsunami modeling applied on two Guadeloupian touristic coastal places: Sainte-Anne and Saint-François

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Section: Introductionmentioning

confidence: 97%

Tsunami hazard assessment of Guadeloupe Island (F.W.I.) related to a megathrust rupture on the Lesser Antilles subduction interface

Roger

Dudon

Zahibo

2013

Nat. Hazards Earth Syst. Sci.

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“…Coral reef growth, however, has a profound influence on coastal evolution: coral reefs protect island edifices from marine abrasion (incuding during storm surges and tsunamis), provide a barrier that allows significant sediment accumulation within island shelves, and frequently are the most important sediment supplier on the edifices in which they grow (Kennedy and Woodroffe, 2000;Kunkel et al, 2006;Gelfenbaum et al, 2011). Organic growth in general and coral reef growth in particular gain prominence as edifices age (Scott and Rotondo, 1983).…”

Section: Reef Growth and Biogenic Productionmentioning

confidence: 99%

Coastal evolution on volcanic oceanic islands: A complex interplay between volcanism, erosion, sedimentation, sea-level change and biogenic production

Ramalho¹,

Quartau

Trenhaile

et al. 2013

Earth-Science Reviews

153

147

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The growth and decay of oceanic hotspot volcanoes are intrinsically related to a competition between volcanic construction and erosive destruction, and coastlines are at the forefront of such confrontation. In this paper, we review the several mechanisms that interact and contribute to the development of coastlines on oceanic island volcanoes, and how these processes evolve throughout the islands' lifetime. Volcanic constructional processes dominate during the emergent island and subaerial shield-building stages. During the emergent island stage, surtseyan activity prevails and hydroclastic and pyroclastic structures form; these structures are generally ephemeral because they can be rapidly obliterated by marine erosion. With the onset of the subaerial shield-building stage, coastal evolution is essentially characterized by rapid but intermittent lateral growth through the formation of lava deltas, largely expanding the coastlines until they, typically, reach their maximum extension. With the post-shield quiescence in volcanic activity, destructive processes gradually take over and coastlines retreat, adopting a more prominent profile; mass wasting and marine and fluvial erosion reshape the landscape and, if conditions are favorable, biogenic processes assume a prominent role. Posterosional volcanic activity may temporarily reverse the balance by renewing coastline expansion, but islands inexorably enter in a long battle for survival above sea level. Reef growth and/or uplift may also prolong the island's lifetime above the waves. The ultimate fate of most islands, however, is to be drowned through subsidence and/or truncation by marine erosion.Keywords complex, interplay, between, volcanism, erosion, sedimentation, sea, level, islands, change, coastal, biogenic, production, oceanic, evolution, volcanic, GeoQuest Disciplines Medicine and Health Sciences | Social and Behavioral Sciences Publication DetailsRamalho, R. S., Quartau, R., Trenhaile, A. S., Mitchell, N. C., Woodroffe, C. D. & Avila, S. P. (2013). Coastal evolution on volcanic oceanic islands: a complex interplay between volcanism, erosion, sedimentation, sealevel change and biogenic production. Earth-Science Reviews, 127 140-170. AbstractThe growth and decay of oceanic hotspot volcanoes are intrinsically related to a competition between volcanic construction and erosive destruction, and coastlines are at the forefront of such confrontation. In this paper, we review the several mechanisms that interact and contribute to the development of coastlines on oceanic island volcanoes, and how these processes evolve throughout the islands' lifetime. Volcanic constructional processes dominate during the emergent island and subaerial shield-building stages. During the emergent island stage, surtseyan activity prevails and hydroclastic and pyroclastic structures form; these structures are generally ephemeral because they can be rapidly obliterated by marine erosion. With the onset of the subaerial shield-building stage, coastal evolution is essentially ch...

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“…Deep channels through the fringing-reef matrix in particular can allow for the propagation of far more tsunami energy than shoals protected by reefs or islets (cf. Gelfenbaum et al, 2011). The simulations run at MHWS reinforce that during the largest events, run-up is also possible from the lagoon side of the atoll, as the reef flat does not provide a barrier to wave propagation.…”

Section: Summary Of Results From Simulationsmentioning

confidence: 64%

“…This may seem counterintuitive and the reverse of what might be expected. An explanation for this behaviour may come from a simulation study by Gelfenbaum et al (2011) that explored the effect of fringing reefs on tsunami inundation in American Samoa. Their study suggested that when fringing reefs are narrow (< 200 m wide), greater wave amplitudes onshore are encouraged by shoaling interaction with the fringing reef.…”

Section: Tsunami Evacuation Advisory: Identifying Key Information Relmentioning

confidence: 99%

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Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

Orpin

Rickard

Gerring

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract. Devastating tsunami over the last decade have significantly heightened awareness of the potential consequences and vulnerability of low-lying Pacific islands and coastal regions. Our appraisal of the potential tsunami hazard for the atolls of the Tokelau Islands is based on a tsunami source-propagation-inundation model using Gerris Flow Solver, adapted from the companion study by Lamarche et al. (2015) for the islands of Wallis and Futuna. We assess whether there is potential for tsunami flooding on any of the village islets from a selection of 14 earthquake-source experiments. These earthquake sources are primarily based on the largest Pacific earthquakes of M w ≥ 8.1 since 1950 and other large credible sources of tsunami that may impact Tokelau. Earthquake-source location and moment magnitude are related to tsunami-wave amplitudes and tsunami flood depths simulated for each of the three atolls of Tokelau. This approach yields instructive results for a community advisory but is not intended to be fully deterministic. Rather, the underlying aim is to identify credible sources that present the greatest potential to trigger an emergency response.Results from our modelling show that wave fields are channelled by the bathymetry of the Pacific basin in such a way that the swathes of the highest waves sweep immediately northeast of the Tokelau Islands. Our limited simulations suggest that trans-Pacific tsunami from distant earthquake sources to the north of Tokelau pose the most significant inundation threat. In particular, our assumed worst-case scenario for the Kuril Trench generated maximum modelledwave amplitudes in excess of 1 m, which may last a few hours and include several wave trains. Other sources can impact specific sectors of the atolls, particularly distant earthquakes from Chile and Peru, and regional earthquake sources to the south. Flooding is dependent on the wave orientation and direct alignment to the incoming tsunami.Our "worst-case" tsunami simulations of the Tokelau Islands suggest that dry areas remain around the villages, which are typically built on a high islet. Consistent with the oral history of little or no perceived tsunami threat, simulations from the recent Tohoku and Chile earthquake sources suggest only limited flooding around low-lying islets of the atoll. Where potential tsunami flooding is inferred from the modelling, recommended minimum evacuation heights above local sea level are compiled, with particular attention paid to variations in tsunami flood depth around the atolls, subdivided into directional quadrants around each atoll. However, complex wave behaviours around the atolls, islets, tidal channels and within the lagoons are also observed in our simulations. Wave amplitudes within the lagoons may exceed 50 cm, increasing any inundation and potential hazards on the inner shoreline of the atolls, which in turn may influence evacuation strategies. Our study shows that indicative simulation studies can be achieved even with only basic field information. In part, this ...

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Effects of fringing reefs on tsunami inundation: American Samoa

Cited by 82 publications

References 38 publications

Tsunami hazard assessment of Guadeloupe Island (F.W.I.) related to a megathrust rupture on the Lesser Antilles subduction interface

Tsunami hazard assessment of Guadeloupe Island (F.W.I.) related to a megathrust rupture on the Lesser Antilles subduction interface

Coastal evolution on volcanic oceanic islands: A complex interplay between volcanism, erosion, sedimentation, sea-level change and biogenic production

Tsunami hazard potential for the equatorial southwestern Pacific atolls of Tokelau from scenario-based simulations

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