Yellowstone National Park geologist Hank Heasler was lecturing a group of colleagues in Biscuit Basin on the rarity of hydrothermal explosions last week when – Boom! A hot pool behind him exploded, spewing mud, rocks and hot water 50 feet in the air.
Sounds exciting. I remember when Porkchop Geyser exploded at Norris in 1989 (I didn't witness it myself, but it was well discussed). Porkchop had been a perpetual spouter for several years, erupting continuously and building up a huge cone of ice during the winter and lasting far into the summer. After the explosion, it turned into a quiet pool that was occasionally known as "Chopped Pork."