5.5-magnitude earthquake off Sicily closes Palermo schools and tests new tsunami warning system

A 5.5-magnitude earthquake struck the southern Tyrrhenian Sea off the northern coast of Italy’s Sicily at 12:19 local time on Friday, October 23, as part of a continuing seismic sequence that alarmed Palermo and the Aeolian Islands, prompting authorities to issue a temporary tsunami alert that was later canceled and to close schools and universities as a precaution.

Series of successive tremors

According to the regional Civil Protection department in Sicily, the sequence began early on Thursday, October 22 at 05:37, with magnitudes ranging between 2.2 and 5.5 at depths of 8 to 32 kilometres. The epicentres were concentrated at sea about 20 kilometres northwest of the island of Alicudi and about 80 kilometres north of the town of Cefalù. The National Institute of Geophysics and Volcanology recorded 69 tremors of magnitude 2 or greater between October 20 and 23, including a second 5.0 shock on Friday afternoon.Civil Protection in Sicily)

Residents felt the main shock in Palermo, Catania, Trapani and the Aeolian Islands, reaching as far as the Calabria region. Shaking intensity maps estimated effects up to level V on the Mercalli scale in the islands and northern Sicily. No human casualties were reported, while local reports said there were rockfalls on the islands of Alicudi and Filicudi away from populated areas, and that schools on the islands were evacuated.

One-hour tsunami alert

The Tsunami Warning Center of the National Institute of Geophysics and Volcanology said it sent an initial information message to the Civil Protection authority at 12:23, then raised the alert level at 12:29 to an orange “watch,” meaning the possibility of small waves under 50 centimetres. Messages were also distributed to Mediterranean countries participating in the service, since the center provides tsunami-warning services for UNESCO in the region. After checking tide-gauge readings at Strombolicchio and Ginostra, no tsunami wave was detected and the alert was canceled at 13:22.

First test of a probabilistic warning system

The institute said this event is the first the center has handled in the Mediterranean since the activation of a new methodology known as probabilistic tsunami forecasting, a method that estimates the probability that an earthquake will generate a tsunami and its potential impacts on coasts, taking into account uncertainties in wave generation and propagation. It confirmed that the calculation procedures and the transmission of messages to Civil Protection and then to local authorities “worked very well,” calling the episode “a test of the system passed with distinction.”Italian Tsunami Warning Center)

Closure of schools and universities in Palermo

Palermo Mayor Roberto Lagalla signed a precautionary order closing schools at all levels, public and private, and university facilities until 08:00 on Sunday, October 25, and activated the municipality’s Civil Protection structures to inspect buildings and infrastructure, starting with the most fragile and important. The order urged residents to limit private car travel to essential journeys so as not to hinder ambulance teams, and asked operators of crowded venues to verify the safety of their premises and prepare evacuation plans.

Area known for seismic activity

The area lies close to the volcanic Aeolian archipelago, classified among Italy’s high seismic-risk zones. One of the notable historical quakes there was the May 28, 1980 event of magnitude 5.7, which caused damage on Alicudi; the same area experienced a sequence of more than 50 tremors west of the island in March 2026.