When it comes to volcanoes, most people worry about a pyroclastic flow from a supereruption, or an outpouring of lava, taking them out. Unfortunately, it’s the more subtle elements of a volcanic system, like mobile gases and vapors, that many more people should be wary of.

As a particularly grim case in point, three members of the same family have died at Solfatara crater near Pozzuoli, Italy, after they were consumed by the acidic fumes that were pouring out of its core.

According to reports, the family of four, from Turin, were visiting the otherworldly sulphur-emitting monster when one child (11) ran through a safety barrier and fell in to the more volatile part of the crater. The mother and father rushed in to help, and were said to have died instantly. A second child (7) survived the ordeal by refusing to move.

Solfatara is powered by the same magmatic source that is fueling Campi Flegrei, Italy’s dormant and increasingly threatening supervolcanic caldera. Unlike most volcanic centers, Solfatara is known for its lack of lava or explosive eruptions, and is instead famous for its foul-smelling, yellow-tinted sulphur emissions.

It formed around 4,000 years ago, and last erupted in the conventional manner back in 1198. Back then, groundwater mixed with hot rock and magma beneath the surface, which triggered highly explosive steam-based eruptions, similar to the sort that nearly killed a BBC film crew on Mount Etna back in March of this year, but in this case with no lava being ejected.

Today, it’s technically dormant, but an active magmatic system sits right beneath the surface. It superheats groundwater under incredible pressures, which erupt out of vents at the surface along with plenty of sulfuric gas. When the two combine, they form an overwhelming cloud of sulfuric acid, which can render a person unconscious within mere moments.

Sometimes this gas gets trapped beneath the surface; when enough pressure builds up, it explodes – a highly unpredictable threat.

Solfatara, seen here emitting sulfuric acid vapor and superheated water. Landscape Nature Photo/Shutterstock

As reported by BBC News, the thin crust in the center of the crater collapsed under the family’s combined weight, which caused them to fall several meters down into the volcanic system itself. They likely died from inhaling the superheated, acidic fumes.

Diego Vitagliano, a local worker at the site, told journalists that the accident was the worst thing he’d ever seen.

If you wish to visit a volcanic system, especially one that features geothermal hot springs or gas-emitting fumaroles like those at Solfatara, please do not cross over the safety barriers, and if you have children, make sure they’re holding your hand at all times. Volcanoes may be spectacular, but they’re also incredibly dangerous, and certainly not to be underestimated.

[H/T: R.it Naples]