The occurrence of tsunamis impacting the UK is rare, with only two (possibly three) having been identified; a 3m high wave as a result of the 1755 Lisbon earthquake, and a 21m high tsunami in 6100 BC which occurred under very different geological conditions (Storegga Slide). In recent years there has been an accumulation of evidence indicating that the 1607 Bristol Channel floods may also have resulted from a tsunami that rose from a height of 4m to over 6m as it passed up the channel.