January 30, 1607 Tsunami: Bristol Channel, England, United Kingdom

Ref #10997:

1607, January 30. At approximately 0900 (all times are local), the lowlands surrounding the Bristol Channel suffered possibly the worst coastal flooding on record. The flood waters caused extensive damage to Bristol and many surrounding villages on the Somerset levels as well as Barnstaple in North Devon. Reports from parish registers and contemporary pamphlets also detail the devastation caused to the Gwent levels on the north side of the Bristol Channel.

It has been postulated that a tsunami may have been responsible for the flooding. However, these analyses rely heavily on geomorphological evidence and inferences drawn from the historical erosion of wetlands. The authors underestimate the significant volume of water associated with a storm surge and the coastal damage that surges can cause. Another important fact, overlooked by those sources, is that areas on the opposite side of the country flooded on the same day.

Ref #3053:

1607, January 30. 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. Tsunami wave heights increased from 4 m in the outer Bristol Channel to more than 6 m within the inner Severn Estuary […] The 1607 flood appears to have been restricted to the coast and coastal lowlands of Bristol Channel and the Severn Estuary, catastrophically flooding 518 km2 along 570 km of coastline and causing 2000 recorded deaths and great economic loss. The area affected by the 1607 flood extended from Barnstaple [Devon] and Carmarthenshire coast in Bristol Channel to the head of the Severn Estuary at Gloucester. Some local churches record the flooding with commemorative plaques.

Ref #11945:

It is unlikely that an earthquake could have caused a tsunami directly as seismic events around Britain are not expected to be large enough to generate significant surface rupture to initiate a tsunami. Also there are no reports of damage to buildings to indicate a local earthquake. If it was a distant earthquake and its epicentre located further away then if it triggered a tsunami it could be expected that the wave would be wide ranging and not restricted to the Bristol Channel. If the origin is a submarine landslide, extensive bathymetric surveys do not reveal any evidence of a slide within the Bristol Channel. Large landslides usually occur on the upper slopes of continental margin such as seen south of Ireland. A tsunami from such a source could be expected to have simultaneously struck the coasts of Ireland, UK and France.

Ref #14326:

The exceptional high tide (14.36m above chart datum) that occurred at 9am combined with the severe weather points to a storm surge as the more likely explanation. The most authoritative account says that a westerly gale blew for 16 hours although some records state that a strong south-west wind blew unbroken for three days (Horsburgh and Horritt, 2006). Note that this event occurred when many places in the United Kingdom were using the Julian Calendar rather than the Gregorian Calendar now used and so is recorded as 20th January 1606.