One hundred years ago, an earthquake caused widespread panic in Malta, sending “partially dressed” people running out of their homes and causing stampedes in churches.

“At first the swelling roar of the earthquake was not understood, but when the edifices started rocking and the walls appeared to crease in snake-like, sinuous undulations, panic seized the whole congregation,” The Daily Malta Chronicle reported.

The congregation “with one irrepressible cry rushed in a mass for the street doors,” the paper said, adding that a jam at the entrance caused some people to be knocked down and trampled on.

The reportedly severe tremor of September 18, 1923, lasted 10 to 12 seconds. It struck at around 7.30am and was mainly felt in Valletta and Cottonera, but also in Rabat, Mdina and Gozo to a smaller extent.

According to research by Pauline Galea, associate professor at the University of Malta’s Department of Geosciences, people took refuge in gardens and open spaces, as well as by the sea.

Many houses in Valletta and Cottonera sustained cracks, while stone crosses fell off the church façade of the Madonna tal-Pilar church in the capital and the St Philip church dome in Senglea.

Parliamentary documents show that at least £1,000 was allocated towards the repair of government buildings.

“A police report of the time specifically mentions ‘serious damages’ to the Cecil Hotel in Old Bakery Street, Valletta, while the dome of St Paul’s church in Rabat suffered serious cracks. These damage reports allow us to associate an intensity of VI on the European Macroseismic Scale,” Prof Galea said.

At the time, tremors were recorded on a Milne seismograph of the horizontal pendulum type at the university’s Valletta campus.

Unfortunately, the intensity of the preliminary tremors had shifted the pilot lamp out of its position.

Combined with the fact that the earthquake occurred near the end of the drum recording for the period between September 14 and 18, only a small section of the recording is visible.

Luckily, the earthquake was recorded by other stations in Europe, with the International Seismological Summary Report for 1923 estimating the epicentre to be at 35.5N, 14.5E, around 40km south of Valletta.

“Although locating the epicentre from such a sparse data set is very difficult, this is probably close to the correct location, given that the largest effects were felt in Malta and not in Gozo," Prof Galea said.

“It is also possible to speculate that the origin of this shock might have been on the Malta Graben, the source of an earthquake sequence in September 2020.

"It is very difficult to estimate the magnitude of the event without more instrumental information but given that it was recorded at such large distances, it would be safe to assume a magnitude of five or higher.”

The September earthquake was not the only seismic event that year: in January, a sequence of tremors was felt mainly in Gozo, where people spent the night in the open.

People also organised pilgrimages to the Ta’ Pinu sanctuary.

The concern was so great that on January 19,  Enrico Mizzi petitioned for military tents to accommodate Gozitans “who might be obliged to sleep in the open during the earthquake shocks”.

His request was eventually refused.

Why are such events relevant to the current generations?

Prof Galea notes that the January tremors were probably part of an earthquake swarm similar to that recorded in January of this year. A swarm may continue for days, months or years.

Dozens of tremors were recorded over a matter of weeks at the start of 2023, prompting some concern due to their frequency. Most of these were too small to be felt, but a few exceeded magnitude 5.0, the largest occurring on January 30. In this case, the swarm occurred more than 100km south of Malta, and caused no damage.

Prof Galea told Times of Malta it was important to study seismic history as far back as possible to have a more accurate estimate of a particular locality’s expected seismic hazard and to better understand active faults in a region.

“Although some speculation about past seismic activity is necessarily involved owing to lack of instrumental data, the information available still provides insight on the activity of fault structures close to our islands.

“Using present-day seismic activity analysis, it is now possible to answer the questions that the Maltese of 100 years ago were probably asking. It is also worth noting a comment in the Daily Malta Chronicle that ‘thanks to the stability of our buildings, the damage reported, as far as can be ascertained, is not serious’.

“Hopefully, we can put the same trust in the quality of today’s buildings when the next similar earthquake strikes.”