Why do geysers erupt?

Full story: newscenter.berkeley.edu/2015/0...
Why do geysers erupt? Loops in their plumbing.
Volcanologist Michael Manga and his students have studied geysers in Chile and Yellowstone National Park, threading sensors and cameras into the boiling water, and have come up with an explanation for why geysers erupt periodically. They’ve even built a laboratory geyser that erupts every 20 minutes. The key: the loops and bends in their plumbing.
Video by Roxanne Makasdjian and Phil Ebiner, with geyser footage by Eric King and Kristen Fauria
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[@Mirro0522]

In this video I really can feel why UC Berkeley is a great university...

[@dabcorn]

Question: at Yellowstone (Grand Geyser I think it was) the geyser (at least in 1994) was surrounded by a HUGE pool of water. If water "fills" the geyser chamber, then, Why did the pool surrounding the geyser completely drain down into the geyser mouth a few minutes BEFORE it erupted???? What's up with that? Thank you.

[@maximedagois48]

thank you for your wonderful documentary

[@Arlemagne]

Per Bak in his book "How Nature Works" describes self-organized critical systems. Are Geysers also self-organized critical in that they have events of all sizes?