M5.7 quake off Sicily closes Palermo schools as southern Tyrrhenian swarm intensifies

A magnitude 5.7 earthquake struck the southern Tyrrhenian Sea on Friday at 10:19 UTC — around 12:19 local time — roughly 61 kilometres west-northwest of Leni on the Sicilian island of Salina, making it the largest tremor in a swarm of 55 earthquakes recorded in the region over the past 30 days.

The quake's shallow depth — USGS placed it at 10 km, while EMSC recorded it at approximately 4 km — meant shaking was felt across a wide area of northern Sicily and the Aeolian Islands. USGS assigned an estimated intensity of around IV on the Modified Mercalli scale and issued a PAGER GREEN alert, indicating low expected impacts. No significant casualties or structural damage have been widely reported.

On land, Palermo's mayor Roberto Lagalla signed an ordinance closing all schools and universities of every level as a precautionary measure, activating the city's civil protection structures and reinforcing monitoring across the territory. The measures remain in force until 8 a.m. the following day, according to Sky TG24, "salvo ulteriori disposizioni" — unless further instructions are issued.

salvo ulteriori disposizioni— Roberto Lagalla, Mayor of Palermo

The swarm began around the night of 20 October 2026 in the southern Tyrrhenian Sea, approximately 30 km northwest of Alicudi in the Aeolian Islands, according to Italy's National Institute of Geophysics and Volcanology (INGV). The day before Friday's main shock — on 22 October at 12:19 local time — INGV recorded a magnitude 5.5 event (Ml 5.0) at a depth of 9 km, located about 62 km from Malfa and 63 km from Leni. That event was accompanied by two further quakes of magnitude 4.3 and 4.0, plus 14 events between magnitude 3.0 and 3.9.

Since midnight before Friday's main shock, approximately 30 additional tremors were recorded at sea, with magnitudes ranging from 2.0 to a maximum of 3.4, at depths between 10 and just over 20 kilometres, Sky TG24 reported.

INGV describes this zone as an area of frequent seismicity and high seismic hazard. The Aeolian archipelago has been struck by several earthquakes of magnitude 5 or greater in the historical record, including events on 28 May 1980 (Mw 5.7), 20 May 1957 (Mw 5.2), and 21 May 1957 (Mw 5.3). The 1980 earthquake caused damage rated VI–VII on the Mercalli-Cancani-Sieberg scale on the island of Alicudi. More recently, in March 2026, a sequence of more than 50 earthquakes — the strongest reaching magnitude 4.7 — occurred about 15 km west of Alicudi, just south of the current swarm zone.

INGV's shaking map for Friday's main event estimated ground motion reaching up to intensity V MCS across the Aeolian Islands and a broad stretch of northern Sicily. The agency notes that the area has also experienced very deep earthquakes — some hundreds of kilometres down — linked to the subduction process beneath the region, such as a magnitude 5.3 event on 5 May 2004 at a depth of 255 km.

Aftershocks are continuing and the event remains under review. Authorities have not lifted precautionary measures as of the latest available reports.

Why it matters — A sustained offshore swarm near the seismically active Aeolian Islands has now produced two quakes above M5.5 in two days, prompting precautionary school closures in Palermo and raising questions about how long the sequence will continue.

Sources differ on Earthquake depth: 10 km (usgs.gov) vs ~3.9 km (emsc-csem.org)

Sources differ on Mainshock magnitude (previous day, 22 Oct): Ml 5.0 / Mw 5.5 (tg24.sky.it)

Reported by usgs.gov, tg24.sky.it, open.online, emsc-csem.org, adnkronos.com