Investigating a large tsunami event on the Maltese islands

Abstract

The Maltese Islands have been subject to various tsunamis in the past, some of which were strong enough to modify the shape of our coastlines. Various historians describe an earthquake in 1693, which resulted in a tsunami that affected Xlendi, where the sea "rolled out to 1 mile and swept back a little later". Another tsunami was triggered by the 1908 Messina earthquake, although this had limited impact on the Maltese archipelago, such as localised flooding and minor structural dan1age. On the north-eastern coasts of Malta several erosional forms including 70-ton boulders and 11 m by 6 m large socket forms can be found. A recent study by Mottershead et al. (2014) investigated such geomorphic signatures at the Aħrax Point in Mellieħa and other coastal sites to propose that a 20 m tsunami wave affected the eastern coastline of the Maltese Islands. The objective of this dissertation is to test the validity of this hypothesis by analysing the nature and distribution of sediments along the Aħrax coast and explain the latter using hydrodynamic equations. As will be explained further, an attempt to infer the age of the tsunami event could not be made so the effort was instead shifted in testing Professor Mottershead's model for the Aħrax area in Mellieħa.