Evidence of past tsunami found, scientists suggest re-evaluation of Malta's tsunami risks

Discovery is the result of a three-year geological study by the University of Portsmouth with support from the University of Malta

A team of University of Portsmouth researchers have discovered evidence that Malta's north east coast was battered by tsunami waves, up to 20 metres above sea level in some areas.

The team, lead by Dr Malcolm Bray, spent the past three years conducting a geological study of the north-eastern coast, with help from the Geography department at the University of Malta.

Large boulders found inland have been traced to sources close to the shore, some up to 100 metres away, where they landed after being carried by the waves.

“What all these measurements point to is that an enormous assailing force was responsible. Our calculations show the tsunami wave would probably have been at least four metres high in some places and substantially more powerful than the biggest storm waves on the islands," said Bray.

The researchers now hope to establish the age of the deposits to determine exactly when the tsunami took place

The Mediterranean basin is seismically active and tsunami are a regular occurrence, with a catalogue of them extending back to classical times. Studies of neighbouring coastlines show there has been a major tsunami, on average, every 400 years.

The last major ones in 1169 and 1693 were triggered by earthquakes centred on the Malta escarpment, southeast of Sicily, which directly faces Malta’s north-eastern coast and is only 100 km, or 54 nautical miles away

A tsunami in Malta could also be caused by seismic activity in Greece, where a major event occurred in southwest Crete in AD 365. This implies that Malta would have little warning time - between 30 minutes and 90 minutes - of an advancing tsunami.

This discovery has important repercussions for Malta, where the high population density means that many thousands could be threatened by similarly sized waves.

Bray called for the education of the Maltese on the risk of tsunamis as well the re-evaluation of the tsunami threat by the government in an effort to protect vulnerable coastline communities.

“If people feel an earthquake, they need to know that there is a risk of a tsunami, and if they see the sea recede they should know to get to higher ground. Fortunately in Malta, higher ground is never far away, but people do need to be made aware of the risks," said Bray.