Catastrophic Wave Erosion, Bristol Channel, United Kingdom: Impact of Tsunami?

Abstract

On January 30, 1607, a massive wave from the ocean surged up Bristol Channel in the United Kingdom, flooding more than 500 km2 of lowland along 570 km of coast. It killed 2000 people and is considered Britain's worst natural disaster on land. The wave occurred on a fine day and surprised inhabitants. Contemporary descriptions of the event have many of the characteristics of accounts of recent catastrophic tsunamis. Geomorphic evidence for tsunamis in the channel can be found in the form of transported and imbricated boulders, bedrock sculpturing on coastal platforms and ramps, and, at isolated locations, wholesale erosion of the coastal landscape. Hydrodynamic calculation of the height of the tsunami and flow velocities can be derived from boulder dimensions. Tsunami wave height increased from 4 m in the outer Bristol Channel to more than 6 m within the inner Severn Estuary. Theorized flow velocities range between 11.8 and 18.1 m s1, increasing up the estuary. Under topographic enhancement, these depths and velocities may be sufficient to generate bedrock sculpturing, which is indeed observed at a few locations on rocky headlands in the channel. Interpolation of the amount of cliff retreat at Dunraven Bay indicates that an imbricated boulder train was deposited by tsunami sometime between 1590 AD and 1672 AD, a time span that encompasses the January 30, 1607, event. A B S T R A C TOn January 30, 1607, a massive wave from the ocean surged up Bristol Channel in the United Kingdom, flooding more than 500 km 2 of lowland along 570 km of coast. It killed 2000 people and is considered Britain's worst natural disaster on land. The wave occurred on a fine day and surprised inhabitants. Contemporary descriptions of the event have many of the characteristics of accounts of recent catastrophic tsunamis. Geomorphic evidence for tsunamis in the channel can be found in the form of transported and imbricated boulders, bedrock sculpturing on coastal platforms and ramps, and, at isolated locations, wholesale erosion of the coastal landscape. Hydrodynamic calculation of the height of the tsunami and flow velocities can be derived from boulder dimensions. Tsunami wave height increased from 4 m in the outer Bristol Channel to more than 6 m within the inner Severn Estuary. Theorized flow velocities range between 11.8 and 18.1 m s Ϫ1

Coastal boulder deposit as evidence of an ocean‐wide prehistoric tsunami originated on the Atacama Desert coast (northern Chile)

“…One of the most used characteristics for differentiating between tsunami and storm deposits is the inland distance of inundation (Bryant & Haslett, ; Kortekaas & Dawson, ; Scicchitano et al ., ; Switzer & Jones, ; Goto et al ., ; Richmond et al ., ; Kennedy et al ., ). Tsunamis occur much less frequently but their impact extends hundreds of metres inland (Dudley & Lee, ; Goff et al ., ); therefore, dispersed boulder deposits described beyond the limit of storm inundation have been interpreted as tsunami evidence in different environmental settings (Goto et al ., ; Paris et al ., ; Goff et al ., ).…”

Numerical identification of tsunami boulders and estimation of local tsunami size at Ibaruma reef of Ishigaki Island, Japan

“…Nott (, ) proposed a representative model to derive the minimum storm wave and tsunami heights necessary to overturn a boulder. This model has been used widely by many researchers, especially during the 2000s (e.g., Nott ; Scheffers & Kelletat ; Bryant & Haslett ; Mastronuzzi et al ; Scicchitano et al ), although problems in assumptions of the parameters have been pointed out (Morton et al ; Switzer & Burston 2009b; Goto et al ; Switzer & Burston ). Subsequently, the Nott model was improved (e.g., Benner et al ; Nandasena et al ), although it remains insufficient to differentiate the origin of boulders in some cases (e.g.…”

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

“…51–59) based largely on examples from the SE coast of Australia. Few other studies identify such forms elsewhere, although sculptured forms of postulated tsunamigenic origin are reported from California, USA (Aalto et al ., ) and the Bristol Channel UK (Bryant and Haslett ). Review of this body of work has recommended that further research into these features is required to resolve uncertainties and validate some interpretations (Courtney et al ., ).…”