More than 500 earthquakes took place in the vicinity of Malta over a 19 year period, with most so small they weren't felt by residents.

Scientists from the University of Malta's Department of Geosciences identified the tremors in the country's first national earthquake catalogue.    

The 500 earthquakes took place around the islands between 1995 and 2014 - equating to 26 a year.

They were the recorded on the only seismic station operating on Malta during this period, code-named WDD and located at Wied Dalam, limits of Birżebbuġa. Most of the earthquakes were weak and not felt by residents.

The epicentres were all off-shore and most were located along the graben systems beneath the sea. The grabens are deep submarine canyons which separate Malta from Lampedusa, Pantelleria and North Africa in general.

This new data set provides fresh information about the tectonic activity that takes place around the Maltese islands, particularly highlighting the extent of activity of the grabens and other submarine faults.

Publication co-author Matthew Agius said the catalogue will help scientists determine a more accurate seismic hazard map for the islands in this region.

Since 2014, seven more seismic stations have been installed around the Maltese archipelago, establishing the Malta Seismic Network. The catalogue, he said, will be updated with the processing of more data in the near future.

The project was funded by the Italia-Malta Operational Programme 2007–2013 (SIMIT) and INTERREG V-A Italia-Malta Operational Programme 2014–2020 (SIMIT-THARSY).