The string of tremors that have hit Malta and Gozo in the past week is not uncommon, with the country last experiencing a similar series of seismic activity just two years ago.
Between September and November 2020, over 100 earthquakes of similar ‘intensity’ were recorded only 23km south of Malta, geosciences researcher Daniela Farrugia said.
But unlike the recent spate of tremors, which sparked reports of apartment blocks shaking and tables trembling, only a few of those were felt by residents.
That was down to their lesser magnitude, Farrugia explained.
The intensity felt from an earthquake relies on multiple factors including distance from the earthquake’s epicenter and its magnitude.
While 2020’s streak of seismic activity occurred just 23km away from land – roughly 100km closer than the recent incidents – those tremors were a lesser magnitude, making them harder to detect during day-to-day life.
Geographical distance can also play a part: in Sicily, for example, the recent tremors were not felt with the same intensity as in Malta as the current activity is restricted to a particular fault system that is not connected to Sicily’s fault system, which is further away.
Thursday saw three more tremors from the same area south of Malta as well as another one on Friday morning, bringing the total to 23 tremors in the past 10 days. On top of those 23 that are officially displayed on the university's seismic monitoring website, over 100 smaller tremors have also been recorded in this period.
Will there be larger earthquakes?
Although it is impossible for experts to give an accurate prediction of Malta’s seismic future, historical studies suggest we are unlikely to experience a major incident.
There is no record of earthquakes “with a large magnitude (greater than 6) originating from the fault which is currently active,” Farrugia said.
“So the probability that a large earthquake occurs is minimal.”
“Historically, building damage has been caused by earthquakes from Sicily and Greece, so these are also zones of concern,” she said.
Although Malta’s first digital seismograph was installed in 1995, experts use accounts and reports of earthquakes that occurred before that date to determine their rough magnitude.
People can expect more seismic activity over the next few weeks, though their frequency and magnitude is likely to decrease. However, this is hard to predict with any real degree of certainty as the tremors do not fall under the typical “mainshock – aftershock” sequence, geophysicist Pauline Galea said last week.
“The fault systems around the Maltese islands often demonstrate phases of activity, alternating with quiet periods. The present phase is a normal active phase,” Galea said.
Yet, if a sizeable shake does hit the island, the Civil Protection Department are in continuous contact with the University of Malta’s science faculty and has received training to prepare for the potential event, according to Home Affairs Minister Byron Camilleri.
The government has not currently discussed the tremors on “a political level”, Prime Minister Robert Abela said on Monday morning.