Exhibits > Why
Geysers Erupt > Geyser
Ingredients > Plumbing > Explosions!
The boiling point of water increases with pressure. Therefore, water deep in the earth
can be much hotter than boiling water near the surface. If the pressure that confines this
deep water is reduced quickly, as may occur if there is a change in the underground plumbing
system, large volumes of water may suddenly flash into steam, causing a violent hydrothermal explosion.
In 1881, Colonel Philetus W. Norris, Yellowstone’s second superintendent, witnessed a hydrothermal
explosion at Excelsior Geyser in the Midway Geyser Basin.
Afterwards, Norris described the changes: “The pool was considerably enlarged,
its immediate borders swept entirely clear of all movable rock, enough of which had
been hurled or forced back to form a ridge from knee to breast high at a distance of from 20 to 50 feet (6-15 m) from the ragged edge of the yawning chasm.”
A series of such explosions were repeated in the early 1890s, which likely damaged the feature's plumbing system. Excelsior, once one of the largest geysers in the world, is now a large, boiling hot spring.
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