Earthquake reported on the Aeolian Islands

This afternoon at 14.54 MET the Italian Aeolian Islands were shacked by an earthquake of an estimated 4.5 magnitude after Richter. According to preliminary press releases of the Italian Institute for Geophysics and Volcanology the hypocenter of the earthquakes is situated 6 kilometres east of the island of Lipari, in a depth of 19,1 kilometres. The trembles were averted on the islands of Vulcano, Lipari, Salina and on the coast of Sicily in the cities of Palermo, Catania and of Messina.

Fig.1. Map of the Aeolian Islands (after Wikipedia).

The earthquake triggered some landslides at Lipari, rock fall on the flanks of the mountain of Vulcano and on Salina. In the village of Lipari minor damages are reported and parts of the beach of the island were closed for reasons of safety. Minor rock falls occured on Lipari also two days later (17.08.2010).

The actual information's releases are contradictory. In a first communication 7-4 injured persons on Lipari, resulting from accidents by rock falls- and landslides, were reported, this information was later withdrawn, only one emergency call and damages on buildings and roads are confirmed, there are no casualties (16.08.2010).
This seismic event is not unusual for the area, in fact the region is characterized by frequent, but deep located earthquakes with a small magnitude (ca. 2-3) produced by the subduction of the Ionian plate under the Tyrrhenian plate.

Fig.2. Simplified sketch of the tectonic setting (red lines) of Southern Italy, the Tyrrhenian Sea is moving south, pulled by the receding subduction zone south of the Ionian Sea. Meanwhile Sicily is pushed relative to the Tyrrhenian Sea to the north, in the junction zones eartquakes can generate and volcanism develop.

Stronger earthquakes are much more rare, seismic events with a magnitude of 4 are documented 3 times in the last 4 years (27.02.2006 / 18.08.2007 / 27.10.2008), the strongest earthquake recorded on the Aeolian island occurred on April 15, 1978 with a magnitude of 6.1, the epicentre was located some 30 kilometres more to the south compared to the actual one.

The actual earthquake caused more scare then damage; it was sensed so distinct because of the minor depth of the hypocenter compared to the usual events in the region. Monitoring is still ongoing, and there is the possibility of minor aftershocks in the next days (a minor shake of 2.3 occured Monday evening 16.08.2010).

Online Resources:

Istituto Nazionale di geofisica e Vulcanologia (accessed 16.08.2010)
Video (in Italian) about the seismicity in Italy between 20.07-03.08 (accessed 16.08.2010)