The infants and children huddled in the stone boathouses. The women pressed in next to them. The men crowded in last. They’d all fled Herculaneum on August 24, 79 A.D. as Mount Vesuvius rained destruction on the city, as it did Pompeii and other Roman settlements near the Bay of Naples.

While Pompeii was consumed by ash, Herculaneum was done in by a pyroclastic flow — a fast-moving, dense, extremely hot surge of ash, gas and rock. At the city’s seaside, hundreds of people died that day. The remains of 340 of them have been unearthed since 1980 — some in the boathouses, known as fornici, and some on the beach.

How they died has long been debated. A prevailing hypothesis is that their blood and brains were vaporized by the extreme heat of the pyroclastic flow. At another site in the city, some researchers have proposed that at least one person’s brain turned to glass.

A pair of studies published Thursday offer new evidence for how the Vesuvius eruption killed some of Herculaneum’s people. One in the journal Antiquity challenges the vaporization hypothesis. The researchers who published it say the condition of the bones of the people in the fornici suggest they were protected from instant death by both the stone structure around them and their collective body tissue mass. This protection insulated them from the flow’s intense heat, but they may have suffered more as they were perhaps suffocated or asphyxiated.