Mt. Pinatubo Eruption. Photo by Albert Garcia taken on June 15, 1991 // A volcano's deadly pyroclastic flow - the same thing that buried Pompeii. You can't outrun it: it travels at 700 km/h (450 mph) and you can't weather it in anything but highly specialized shelters: it's over 1,000 °C (1,830 °F). Once you see that in your rear view mirror, you're either already out of reach or you're not.
This area in New Mexico owes its remarkable geology to layers of volcanic rock and ash deposited by pyroclastic flow from a volcanic explosion. Over time weathering and erosion of these layers has created canyons and tent rocks. The tent rocks themselves are cones of soft pumice and tuff beneath harder caprocks, and vary in height from a few feet to 90 feet.
Pyroclastic flow, Philippines. "A pyroclastic flow is a fluidized mixture of solid to semi-solid fragments and hot, expanding gases that flows down the flank of a volcanic edifice. These awesome features are heavier-than-air emulsions that move much like a snow avalanche, except that they are fiercely hot, contain toxic gases, and move at phenomenal, hurricane-force speeds, often over 100 km/hour.
Herculaneum/ Herculaneum (in modern Italian Ercolano) was an ancient Roman town destroyed by volcanic pyroclastic flows AD 79, located in the territory of the current commune of Ercolano, in the Italian region of Campania in the shadow of Mt. Vesuvius. It is most famous for having been lost, along with Pompeii, Stabiae and Oplontis, in the eruption of Mount Vesuvius beginning on August 24, AD 79,