The city was destroyed by a volcanic eruption of mount Vesuvius.
In the study, researchers analyzed 103 fragment of the bones of victims of the eruption using mass spectrometry with inductively coupled plasma method, which allows to determine chemical elements in extremely low concentrations. In the result, it was found that on the surface of some samples was present as inorganic substances, are usually included in the volcanic ash, and organic products of decomposition and carbon oxides, and iron salts.
Binding iron ions complex in the composition of hemoglobin begins to degrade at 70-100 degrees Celsius, and at 400 degrees it breaks down with the formation of iron oxides. The temperature at the periphery of pyroclastic flows hovered at 200-300 degrees Celsius, and in the center can reach 400-500 degrees. The researchers suggested that compounds of iron and carbon formed by the decomposition of the bodies. Probably, the hot air or the ashes have boiled the blood and soft tissues of people, including the brain. The bones of the skull could not withstand the pressure from inside and burst. This led to the instant death of the victims of the eruption.
Herculaneum was located seven kilometers to the West of mount Vesuvius and was destroyed by the eruption in 79 ad. In the aftermath of the first wave of the eruption the cloud of ash destroyed Pompeii and Stabiae. Herculaneum was buried under pyroclastic flows during the second wave of the eruption that happened in a few hours. Therefore, most of the residents of Herculaneum had time to escape. However, several hundred residents chose to stay and took refuge from the eruption in boat sheds on the beach.