Characterisation of erosional features associated with tsunami terrains on rocky coasts of the Maltese islands

Mottershead, D. N.; Bray, Malcolm; Soar, Philip J.; Farres, Paul

doi:10.1002/esp.3784

Cited by 9 publications

(9 citation statements)

References 57 publications

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“…In contrast, however, we are concerned here with the patterns of signatures in Maltese coastal landscapes extending upwards to >20 m asl. Their recent recognition in Malta (Mottershead et al 2014(Mottershead et al , 2015 represents a much more severe landfall impact and would appear to require a different explanation. The recent evidence of Polonia et al (2013Polonia et al ( , 2016a and Köng et al (2016) implies stratigraphic and temporal support for the AD 365 tsunami and at least one previous basin-wide event originating in the Hellenic Arc, as potentially responsible agencies.…”

Section: Resultsmentioning

confidence: 99%

“…The field evidence for historic extreme wave events in the Maltese islands is concentrated along the east coast, clearly indicating wave attack from that direction (Mottershead et al 2014(Mottershead et al , 2015. This is not to suggest that such events are exclusive to the east but rather it offers topographies that act as traps for coastal sediment deposition.…”

Section: Geomorphological Evidence Of Tsunami In Maltamentioning

confidence: 99%

“…A special case is the model of Hansom et al (2008), which describes clifftop boulder detachment. This was used by Mottershead et al (2015) to model the wave required to detach a ~60 t boulder from a clifftop cornice at ~10 m asl (Figure 4) and revealed the required storm wave to be between 9.1 and 28.4 m (depending on the original but unknown orientation of the boulder), which is clearly unfeasible at this elevation and with maximum sea waves of 5.5 m (Drago et al 2013). However, the required power would be produced by a tsunami wave at 10 m asl of between 2.1 and 7.3 m height, which is a more feasible proposition, particularly for a site with extreme wave signatures present up to 22 m asl.…”

Section: Geomorphological Evidence Of Tsunami In Maltamentioning

confidence: 99%

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Tsunami landfalls in the Maltese archipelago: reconciling the historical record with geomorphological evidence

Mottershead¹,

Bray²,

Soar³

2017

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The Maltese Islands lie in the middle of the tsunamigenic Mediterranean domain, around whose margins and islands evidence of historic tsunami landfall has been increasingly recognized in recent years. Critical review of historical evidence of events in 1693 and 1908 indicates extremely modest tsunami impacts. In marked contrast, though, recently discovered geomorphological evidence summarized herein suggests that Malta's coastlines have been overwashed up to elevations of >20 m asl by an exceptional event. A new perspective is provided by a review of the central Mediterranean context within which the Maltese evidence is located. Recent advances in understanding of the Holocene sequence forming the Mediterranean Sea floor present a new stratigraphic and temporal framework within which to elucidate tsunami history. Within 100 km of Malta terrestrial stratigraphy on Sicily also provides supporting evidence of tsunami impact. Review of these advances suggests that the exceptional event required to emplace the most extreme sedimentary and geomorphological signatures on and around Malta is likely to have had a far-field origin. The currently available circumstantial evidence points strongly toward a probability that the AD365 earthquake and tsunami were responsible. This in turn enables critical reassessment of the exposure of Malta to tsunami hazard. Keywords Mediterranean; extreme waves; erosion features; boulder deposits; tsunami; Malta The Maltese archipelago sits on the Malta Plateau atop the Pelagius Platform, a northern promontory of the African plate which extends towards Sicily and separates the deep Ionian Basin from the western Mediterranean. Eastwards at a distance of 120 km the submerged Malta Escarpment forms the steep margin of the Ionian Basin, eastwards of which the sea floor falls to-4000 m (Galea 2007; Micallef et al. 2013). The islands are formed of Neogene sedimentary rocks

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Section: Resultsmentioning

confidence: 99%

Section: Geomorphological Evidence Of Tsunami In Maltamentioning

confidence: 99%

Section: Geomorphological Evidence Of Tsunami In Maltamentioning

confidence: 99%

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Tsunami landfalls in the Maltese archipelago: reconciling the historical record with geomorphological evidence

Mottershead¹,

Bray²,

Soar³

2017

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“…Microseismic energy is transferred into the landward cliff with cliff top vibrations being correlated with significant wave height and water maximum depth at the cliff base (Young et al, 2016). While wind-generated waves of gravity to infragravity frequency are the primary energy input, the instantaneous impact of longer period tsunami waves also can drive landscape formation in some circumstances, as is observed in the erosional scars on the platforms and cliffs of the Maltese Islands (Mottershead et al, 2015).…”

Section: Instantaneous Scalementioning

confidence: 99%

The temporal and spatial scales of rocky coast geomorphology: a commentary

Kennedy

Coombes

Mottershead

2017

Earth Surf Processes Landf

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Rocky shores are complex landforms that result from marine erosion and subaerial weathering. They are time-integrated features where their present day form is the result of instantaneous erosion, often on the millimetre to sub-metre scale, occurring for centuries to millennia. As a result, research on rocky coasts focuses on a range of temporal and spatial scales from granular-scale swelling of a rock surface and instantaneous wave impact to modelling millennial-scale sea level drivers. The challenge for rocky coast researchers is either to upscale or to downscale their results to the humantimescales of greatest interest to managers. The research presented in Earth Surface Processes and Landforms over the past 3 years highlights the range of spatial and temporal approaches to the study of coastal cliffs and shore platforms. We identify a key temporal and spatial gap in current research. Seasonal -annual timeframes over hundreds of metres to kilometre scale studies appear to be lacking and are likely critical in understanding the future evolution of rocky coasts, especially their response to climate change.This article is

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“…The location of Malta in the centre of the Mediterranean Sea means that it is exposed both to storm waves and tsunami [12,25]. Recent research has presented evidence of extreme wave impacts on Maltese coasts at elevations up to >20 m above sea level (asl) [7,8,26]. The evidence embraces a range of both depositional and erosional signatures, with many existing features within the range of potential storm wave energy [8] and some outlying features being interpreted as tsunamigenic in origin [7,26].…”

Section: Introductionmentioning

confidence: 99%

Reconstructing Boulder Deposition Histories: Extreme Wave Signatures on a Complex Rocky Shoreline of Malta

et al. 2020

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The Żonqor coastline, southeast Malta, displays an exceptional range of geomorphic signatures of extreme coastal events. This paper brings together evidence acquired from a field survey, analysis of time-sequential imagery, and hydrodynamic modelling to investigate the histories of boulder groups identified by their intrinsic and contextual characteristics. Clear differences are revealed between the distribution of boulders recently moved and those of considerable age. Tracking the movement of boulders since 1957 confirms that storms of surprisingly frequent interval are capable of complex boulder movements, including lifting of megaclasts. Scrutiny of the ancient boulders, including weathering features and fascinating landward-facing (reverse) imbrication, cautiously suggests tsunami as the agent for their emplacement. A novel method is developed for depicting the velocity decay profiles of hypothetical waves, which overcomes some of the limitations of the Nott approach. Applied here, the wave run-up context further sets the ancient movers apart from their recent mover companions. The combined evidence implies a palimpsestic landscape where storm waves are regular geomorphic agents that add to and rework the distribution of boulders close to the shoreline, but over long time periods the landscape becomes reset by tsunami—a concept that is of value to agencies in Malta responsible for coastal safety, planning and management.

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Characterisation of erosional features associated with tsunami terrains on rocky coasts of the Maltese islands

Cited by 9 publications

References 57 publications

Tsunami landfalls in the Maltese archipelago: reconciling the historical record with geomorphological evidence

Tsunami landfalls in the Maltese archipelago: reconciling the historical record with geomorphological evidence

The temporal and spatial scales of rocky coast geomorphology: a commentary

Reconstructing Boulder Deposition Histories: Extreme Wave Signatures on a Complex Rocky Shoreline of Malta

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