Not very often, as the Atlantic has fewer tsunamis in general than the Pacific or Indian Oceans, and it is difficult to identify small tsunamis without the otherwise energetic tide gauge records. However, two famous examples in the historical record may be quoted. Storegga landslip - Along the coasts of the northern North Sea, Norwegian Sea and north eastern Atlantic Ocean a very prominent sand layer was originally thought to have been deposited by a storm surge.
More recently, it has been attributed to a large tsunami circa 7,100 years ago. Lisbon earthquake (1755) - probably the most destructive tsunami in Europe during historical times occurred on 1st November 1755. An earthquake (now known as the Lisbon Earthquake) took place 200 km offshore from Portugal. The subsequent tsunami destroyed a large part of Lisbon and raised sea levels at Newlyn (Cornwall, UK) by up to 3 metres in ten minutes.