Picture Old Faithful, the iconic geyser that erupts on a clockwork-like schedule every 91 minutes in Yellowstone National Park. Researchers have long studied this geyser, as it is an intriguing example of the natural phenomena and provides key clues as to how geysers may work. However, not every geyser is as predictable as this good ol' cone geyser, and until now the various forces behind their impressive displays remained a mystery.
Michael Manga, a researcher at the University of California in Berkeley, believes that the fundamental key to geyser eruptions is an underground bend or loop that traps steam. This steam bubbles out slowly, heating a column of groundwater just above it until it climaxes in a sudden spurt of boiling.
Now here's where things get complicated: geysers look like they are shooting upward, and yes, the water actually is. But the boiling mechanism that expands the water and fires it out is actually flushing downward, releasing pressure from top-to-bottom as the entire column boils. This causes water and steam to launch hundreds of feet in the air in a kind of slingshot form of momentum, rather than simply boiling over like an overfilled pot on a stovetop.
"Most geysers appear to have a bubble trap accumulating the steam injected from below, and the release of the steam from the trap gets the geyser ready to erupt," Manga elaborated in a statement. "You can see the water column warming up and warming up until enough water reaches the boiling point that, once the top layer begins to boil, the boiling becomes self-perpetuating." [Manga explains more in the video below.]
So how did the researchers determine this? Manga and his team spent the past several years studying geysers in Chile and Yellowstone, making never-before-seen observations after feeding temperature and pressure sensors into their cavities on long lines. (Scroll to read on...)
As invasive field work is forbidden in Yellowstone, the great majority of their hard data came from a geyser in the Atacama desert of Chile, dubbed El Jefe (The Cheif). Over six days of observation, El Jefe erupted about 3,600 times, boiling water to about 187 degrees Fahrenheit. They compared this data to observations and above-ground data taken from Yellowstone's own geyser fields.
This data helped them formulate several theories that they then tested back at their lab in proof-of-concept experiments. The results were recently published in the Journal of Volcanology and Geothermal Research.
But why was Manga and his team so hung up on geysers in the first place? Believe it or not, there is still a lot about awe-inspiring natural phenomena, such as glacial shifts, volcanoes, and, yes, even geysers, that we know nothing about. Tack on the fact there are fewer than 1,000 known geysers around the world and you've got yourself a tantalizing mystery.
And if researchers could completely solve this mystery, it may help them better understand others. Manga says that studying geysers may also help experts gain insight into volcano eruptions. They may very well have similar mechanics, but no sensor or pressure set could ever survive being fed into the fiery and dense cavity of a volcano.
"One of our goals is to figure out why geysers exist - why don't you just get a hot spring - and what is it that controls how a geyser erupts, including weather and earthquakes," Manga added.
Even now, with this understanding of the "loop" mechanic, there is still much more work to be done.
[Credit: Roxanne Makasdjian and Phil Ebiner, with add. footage by Eric King and Kristen Fauria]
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