The earthquake of 16 December 1857 and the expedition to the ‘Napoletano’ region

On the evening of 16 December 1857, three earthquakes struck the ‘Napoletano’ region and devastated a vast area of Basilicata and part of Campania, affecting the present-day province of Potenza and the central-eastern part of the Salerno area. The most severe damage was suffered by the Agri valley and the most remote and isolated areas. Out of a total of 182 affected localities, more than 30 were almost completely razed to the ground. The death toll was staggering. According to official estimates, 10,939 people lost their lives, of whom 9,732 were in the Potenza area and 1,207 in the Salerno area.
The lack of transport links and damage to the long-distance communications system (which at the time relied on the electric telegraph) slowed down the arrival of relief efforts and the assessment of the damage suffered. It was only after three months that an initial official estimate was produced. Reports on the earthquake were gathered locally by the intendants (the King’s local representatives), reached Naples slowly and were published in the *Giornale del Regno delle Due Sicilie*.
Through the British press, Robert Mallet learnt of the earthquake and applied to the Royal Society in London for funding to organise a scientific expedition to the affected areas. He believed that by observing the natural characteristics of the affected territory and the physical signs left by the earthquake, and by analysing the mechanical action of the seismic wave on the various solid bodies affected by the tremor, it would be possible to trace the position (both on the surface and at depth) of the seismic source and determine the epicentre of the earthquakes.
The earthquake in the ‘Neapolitan region’ presented a rare and long-awaited opportunity to demonstrate how the scientific principles – developed over a period of fifteen years – could be put into practice in the field. Thanks to a grant of 150 pounds awarded on 27 January 1858, Mallet – armed with numerous letters of introduction and recommendation provided by members of the nobility and the scientific community in London – was able to set off from England to undertake his expedition.