Mr. Hiscock said further investigation showed that it was a result of "a shift in underground plumbing."

USGS scientist Shaul Hurwitz along with colleagues at Stanford and Yellowstone National Park have discovered that changes of water supply to a geyser's underground plumbing may have a large influence on eruption intervals; that is, the time between eruptions.

The underground plumbing of hot water and magmas beneath Yellowstone is influenced by the same stresses that cause earthquakes.

If nothing else, the intake sluices and outflow pipes must need maintenance from time to time; and you can't hide a bunch of workers playing around with giant underground plumbing.

Washing pots, cleaning out disgusting greasetraps in the underground plumbing, slaving at the most menial tasks that generations of warped minds had created.

With his own crew, Mr. Levi built the foundations for full basements, the sidewalks and sewer and water-main connections, and the interior and underground plumbing and carpentry finishing.

Its use as a street tree is being phased out in some locales because of the damage it often causes to pavements and underground plumbing.

"The underground plumbing of a mud volcano, I don't think, is going to be that simple," he said.

As he spoke, at 1:35, the prehistoric underground plumbing rumbled to life.

He attributed the poor condition of park fountains to their age, which he said generally exceeds 50 years, and complex underground plumbing.