Vesuvius and Pompeii: The Volcano Behind the Ruins

Vesuvius is the volcano that buried Pompeii in AD 79, about 10 km away, and it has been quiet since its last eruption in 1944. It is not one cone but two: Monte Somma, an older building with a collapsed rim, and the Gran Cono, the younger cone that grew inside it after the eruption that destroyed the town. Italy's Civil Protection Department lists the volcano as quiescent, with the alert level at green, and the Osservatorio Vesuviano of the national institute INGV watches it around the clock. We read that page on November 5, 2026.

Volcanologists call the whole complex Somma-Vesuvius. According to the Civil Protection Department it has an older building, the Somma, marked by a caldera, and a younger cone, the Vesuvius proper, that grew inside the caldera after the eruption of AD 79. From the bay you can pick out the Somma as the curved ridge beside and behind the cone. Its age is under 39,000 years. Between about 39,000 and 20,000 years ago, eruptions were mostly effusive, with some low-energy explosions, and that is when the Somma was built.

The point for visitors is that the cone you see now is not the mountain the Romans knew. Strabo, writing decades before the eruption, describes the upper part as ash-colored, with rocks that looked eaten away by fire, and guessed that it had once burned. Cassius Dio, who wrote more than a century after 79, compares the mountain to a hunting theatre, hollow in the middle and ringed by intact heights. Neither is a description of the cone you see now. The cone arrived afterward.

Partly. The mountain had rested for about three centuries before 79, a gap the Civil Protection Department gives, and farmland climbed its slopes. Strabo's remarks show an educated guess, not a warning. Pliny the Younger, whose two letters to Tacitus are the main written account, does not mention Pompeii or Herculaneum at all. He writes that, seen from across the bay, the cloud rose from a mountain nobody could name at first, and adds one clause:

Before that, the mountain's history was a series of long rests broken by very large events. About 18,000 years ago, after a long pause, the volcano produced its first Plinian eruption (the Pomici di Base). More followed, each after a long quiet spell: the Pomici di Mercato about 8,000 years ago and the Pomici di Avellino about 3,500 years ago, before the eruption of 79. The hour-by-hour account of that day is in our guide to the eruption of AD 79. Here we start the day after.

From 1631 to 1906 the volcano showed almost continuous Strombolian activity with lava flows, and rests of only a few years. Scientists place the end of that open-conduit period at 1944. So "how often does Vesuvius erupt" has two answers. Between 1631 and 1944, often. Before 1631, rarely, but violently, with rests of centuries.

The scientific word is quiescent, and the official description is specific. Since 1944 the volcano has been in a rest with a plugged, or closed, conduit. It has produced only fumarolic activity and seismic swarms of moderate energy, the Department says, with no ground deformation and no significant change in physical or chemical parameters. It also says that no precursory phenomena that would indicate a short-term resumption are being recorded. We quote that, as of November 5, 2026, and we do not forecast.

The record shows that long rests end in strong eruptions, and that the volcano has been resting since 1944. It does not show when anything will happen. Neither do we.

What do the experts consider likely? Based on recent studies, the Department says the most probable event is a violent Strombolian eruption (VEI 3) with fallout of pyroclastic material and mudflows. A geophysical survey found no shallow magma chamber large enough to produce a Plinian eruption, so it calls that unlikely. The emergency plan nevertheless uses a larger, sub-Plinian event like the one of 1631 as its reference scenario. That is what planning does: it prepares for the stronger case without saying that it is coming. Our page of Pompeii myths and facts checks several claims about the mountain.

The monitoring network of the Osservatorio Vesuviano, the Naples section of the national institute of geophysics and volcanology (INGV), watches Vesuvius 24 hours a day. The Department names two competence centers: the Osservatorio Vesuviano and IREA, the electromagnetic sensing institute of the national research council (CNR). Based on what they report, the Civil Protection Department declares an alert level and an operational phase, in agreement with the Campania Region and after hearing the Major Risks Commission.

There are four levels: green, yellow (attention), orange (pre-alarm) and red (alarm). Green means that no anomalous phenomena are recorded compared with the ordinary activity of recent decades. The Department publishes the current level at the top of its Vesuvius page, and the national public alert system is called IT-alert. Our statement that the level was green is dated November 5, 2026; for anything later, read the Department's page and not ours.

Pompeii is in the red zone. So is Herculaneum. That is a fact about administrative boundaries drawn around the hazard, and it applies to the roughly 700,000 people who live at the foot of the volcano, a figure the Department gives (the plan page gives 670,000 for the red zone). It is why the volcano appears in emergency planning for the whole area. We found no guidance from the Department or the Park asking visitors to change their plans. The plan is built for residents; if an alert level ever rose, you would follow the instructions of the authorities and of the Park's staff, as anyone else on site would.

Yes, but not to the crater. As of November 2026, according to the Park of Vesuvius, the open trail ends at the Capannuccia, at 1,170 m. The loop path and the highest section are closed. The Park says tickets for the Gran Cono are sold exclusively online, and the pages we read quote two different ticket prices, so we do not print one.

A mountain visit and a Pompeii visit work well on separate halves of the day or on separate days. For tickets and logistics, see our category Pompeii and Vesuvius, which compares combined options. For wind, rain and temperatures, see our climate page. One classic view of the volcano from the ruins is from the Forum.