The eruption of Mount Vesuvius in AD 79 destroyed the Roman cities of Pompeii, Herculaneum, Oplontis and Stabiae, as well as several other settlements. The eruption ejected a cloud of stones, ashes and volcanic gases to a height of , erupting molten rock and pulverized pumice at the rate of per second, ultimately releasing 100,000 times the thermal energy released by the atomic bombings of Hiroshima and Nagasaki. More than 1,000 people are thought to have died in the eruption, though the exact toll is unknown. The only surviving eyewitness account of the event consists of two letters by Pliny the Younger to the historian Tacitus.