Mount Vesuvius erupts in the first year of Titus' reign and buries Pompeii and Herculaneum under ash.
There happened in his reign some dreadful accidents; an eruption of Mount Vesuvius, in Campania, and a fire in Rome, which continued during three days and three nights
One of the deadliest eruptions in history, it buried towns whose excavation has revealed much of how their people lived.
Based on Wikipedia: Eruption of Mount Vesuvius in 79 AD
In 79 AD, Mount Vesuvius, a stratovolcano located in the modern-day region of Campania, Italy, erupted, causing one of the deadliest eruptions in history.
Archaeological excavations have revealed much of the towns and the lives of the inhabitants, leading to the area becoming Vesuvius National Park and a UNESCO World Heritage Site.