UK meteotsunamis: a revision and update on events and their frequency

A tsunami is a series of waves caused by the displacement of water. The displacement may result from ‘bottom‐up’ seabed movement, such as caused by earthquakes, landslides and volcanic eruptions or ‘top‐down’ movement, from pressure perturbations in the atmosphere. These ‘top‐down’ events are termed meteotsunamis. Meteotsunamis frequently occur in the Mediterranean, the Baltic Sea, the east coast and Great Lakes of North America, and Japan, so they are not exclusive to the United Kingdom. The most recent meteotsunami near the UK coast was in May 2017, when waves around 2m in elevation, generated by a storm passing over the UK, struck the coast of the Netherlands. Historical documents covering the past 150 years describe many meteotsunamis from United Kingdom (UK) coastal waters (Haslett et al ., 2009; Haslett and Bryant, 2009; Tappin et al ., 2013; Vilibić et al ., 2015; O'Brien et al ., 2018). Some of these events have resulted in fatalities, involving beach users who were struck by unexpected sea waves. Meteotsunamis commonly strike the coasts of the UK, damaging harbours, boats and very rarely, causing fatalities. In the UK, they were usually detected by analysis after the event, unless witnessed first‐hand. This post‐event analysis is particularly necessary in the UK because the data provided by the tide gauge system, operated by the Environment Agency, only records at 15‐min intervals, not in real time as in the rest of Europe. The periods of meteotsunamis are in the range of minutes to tens of minutes (Pattiaratchi and Wijeratne, 2015). A frequency of tens of minutes is similar to a typical frequency expected from a meteotsunami that would have an amplified response from harbour or bay resonance (Tappin et al ., 2013). Therefore, those occurring in UK waters are not often recorded with the present tide gauge settings and as a consequence, cannot be analysed effectively