Edward Marchesi Around noon on Friday, October 23, a powerful earthquake struck the Tyrrhenian Sea , felt by residents from Palermo to Catania. The National Institute of Geophysics and Volcanology ( INGV ) recorded the event at 12:19 PM, indicating an epicenter west of the Aeolian Islands, not far from Alicudi, at a depth of approximately 9 km.
The earthquake reached a magnitude of 5.5 , causing a strong vibration for several seconds. Despite its intensity, authorities immediately reported no damage to people or property, but have activated emergency procedures to ensure the safety of schools, public offices, and judicial facilities.
The main earthquake: technical data and affected area
According to INGV surveys, the most vulnerable area is the southern Tyrrhenian coast, where the African tectonic plate interacts with the European one. The magnitude of 5.5 was measured, with enough energy to make the tremor felt more than 200 km away. The event occurred approximately 30 km from the Sicilian coast, making the tremor particularly noticeable in the cities of Palermo and Catania.
Earthquake felt from Palermo to Catania and safety measures in place
Testimonies collected on social media reveal the fear among the population: "The tremor was very strong," "it lasted for several seconds," and there were even reports of aquariums spewing water. As a precaution, the Palermo Prefecture ordered the evacuation of students from numerous schools, as well as some municipal offices and the Prefecture itself. The Trapani courthouse was also evacuated, with magistrates and judicial staff temporarily transferred to safe locations.
The head of the Sicilian Civil Protection Agency , Salvo Cocina, declared a state of alert and requested the prompt action of all affected municipalities. Thanks to this prompt action, the authorities were able to manage the evacuations without incident, demonstrating the effectiveness of the emergency protocols already established in the region.
Seismic swarm: aftershocks recorded within an hour
The main earthquake was followed by a series of aftershocks that kept authorities on high alert. At 10:02, a magnitude 3.9 tremor was recorded at a depth of 25 km, followed by further tremors at 11:04 (M3.3, 9 km), 11:51 (M4.3, 24 km), and 11:56 (M3.6, 32 km). After the main quake, further tremors occurred: at 12:24 (M4.0, 8 km), 12:41 (M3.0, 10 km), 12:43 (M3.2, 10 km), 12:51 (M3.2, 25 km), 12:55 (M3.3, 10 km), and 13:08 (M2.9, 10 km).
A total of nine tremors with magnitudes greater than 3.0 were detected between 10:02 AM and 12:55 PM, confirming the presence of an active seismic swarm . The proliferation of these events prompted the Civil Protection Department to maintain a high alert for several hours, limiting further risks to the population.
Orange tsunami alert and its course
Following the magnitude 5.5 earthquake, the INGV Tsunami Center issued an orange alert, as required by the international protocol for the Mediterranean. The alert was managed by the INGV Tsunami Center , one of four global centers responsible for marine monitoring. Salvo Cocina ordered the immediate activation of coastal protection measures.
Within an hour of its issuance, the alert was lifted because no significant changes in sea level were detected. Seismologist Salvatore Stramondo confirmed the absence of tsunamis, emphasizing that the phenomenon had no observable effects on the coastline.
Seismic context of the week: 60 tremors in 7 days
The magnitude 5.5 earthquake is part of a broader sequence of seismic activity that has affected the southern Tyrrhenian Sea in recent days. According to Salvatore Stramondo, director of the INGV Earthquake Department, approximately 60 tremors have been recorded over the past week, including a dozen with magnitudes greater than 4.0. On October 23 alone, approximately 15 events occurred in the same area, demonstrating the volatility of the geotechnical context.
Constant monitoring by the INGV and the Civil Protection Department has allowed the population to be kept informed and respond quickly in the event of an escalation. Despite the series of tremors, no structural damage or injuries have been reported so far, thanks in part to the prompt action of local authorities.