The lava flow during the eruption of Mount Vesuvius in 79 AD was not the primary cause of destruction in Pompeii; it was actually the pyroclastic flows that were much more dangerous. However, when we talk about lava flow speed, it varies widely based on a number of factors including the composition of the lava, the slope of the land, and the eruption’s intensity.
Generally, lava flows can travel anywhere from a few kilometers per hour to over 30 kilometers per hour (about 18.6 miles per hour) in the case of very fluid lava on steep slopes. In Pompeii’s case, the eruption produced mostly pumice and ash, resulting in rapid pyroclastic surges rather than typical lava flows. These surges could move at speeds of over 700 kilometers per hour (approximately 435 miles per hour), making them incredibly lethal.
In conclusion, while lava flows can be fast, the real danger during the Pompeii eruption came from pyroclastic flows which moved quickly and buried the city under ash, leading to the preservation of its ruins for centuries.