美国国家公共电台 NPR Steamboat Geyser Keeps Erupting And Keeps Baffling Scientists（在线收听）

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Steamboat Geyser in Yellowstone National Park can shoot water up more than 300 feet. It is the tallest active geyser in the entire world. And this year, it has erupted more times than ever before. This streak of activity has thrilled both casual tourists as well as committed geyser gazers. Scientists have been watching as well to try to figure out what exactly is going on. Here's NPR's Nell Greenfieldboyce.

NELL GREENFIELDBOYCE, BYLINE: Steamboat has become a geyser superstar, eclipsing even Old Faithful in terms of public attention. Erin White is Yellowstone's Park hydrologist.

ERIN WHITE: There are people that camp on the sidewalks, you know, spend all of their days, all of their time off sitting next to Steamboat.

GREENFIELDBOYCE: In videos, you can hear people's excitement when all that waiting pays off.

(SOUNDBITE OF PEOPLE CHEERING)

GREENFIELDBOYCE: White remembers when she got to see Steamboat. Last winter, she was driving past and stopped when she spotted a column of steam.

WHITE: And had the very unique experience of being the only person standing next to Steamboat while it was vigorously releasing steam. It is incredibly powerful. It's like standing next to a jet engine.

GREENFIELDBOYCE: Steamboat's had a record year - more than 45 eruptions. That beats the record set last year - 32 eruptions. And in the three years before that, there were zero eruptions. This geyser is not dependable like Old Faithful. The frequency of its eruptions is highly variable. Its sometimes goes quiet for a long time.

WHITE: In the 1960s, there was another period where there were more than 20 eruptions per year. And then prior to that, you know, there were dormant periods of more than 50 years.

GREENFIELDBOYCE: So what changed in 2018 to make this geyser start erupting every seven to 10 days? Scientists wish they knew. White says they've long understood the basic ingredients needed to make a geyser.

WHITE: You need to have a source of water. You need a source of heat. And you need structure - a geologic structure that is constrained or confined in some way to develop pressure that will generate an eruption.

GREENFIELDBOYCE: That combination is rare. The planet has fewer than a thousand geysers. About half are in Yellowstone, where an ancient volcano's magma heats water in underground cavities. You might think scientists would have detailed maps of what's going on beneath Steamboat, but White says they don't.

WHITE: What is the subsurface architecture? What is the volume of water that is available for every eruption?

GREENFIELDBOYCE: They do have temperature sensors deployed around the geyser. And there's been recent research using arrays of seismic sensors. Michael Manga is a researcher at the University of California Berkeley.

MICHAEL MANGA: People always ask, well, why is Steamboat such a tall geyser? And we can't answer that question.

GREENFIELDBOYCE: Not yet, anyway. Recent results show that Steamboat's liquid is stored at depths of about 65 to 130 feet. Manga says the deeper water is stored, the warmer it will be. The heat provides the energy that drives the eruption.

MANGA: At other geysers, that storage seems to be more shallow. And our hypothesis is - for the reason why Steamboat is such a huge guys are and so tall is that the water's stored deeper. The deeper the water's stored, the more energy it can have. And the more energy you have, the bigger the eruption can be.

GREENFIELDBOYCE: Some of the first studies of geysers were done back in the 1800s. by Robert Bunsen - you know, the same guy who developed the Bunsen burner used in chemistry class. Scientists who put video cameras in geysers and built artificial geysers in the lab. Still, many fundamental questions remain unanswered, like what makes some geysers so predictable? Manga says take one of his favorite geysers in Chile.

MANGA: When we were studying it, it erupted thousands of times. And the time between eruptions varied by less than about a second.

GREENFIELDBOYCE: When I started asking Manga about the geyser scientific community, he seemed kind of amused.

MANGA: It's interesting you say - expression geyser scientific community because it's a community of almost nobody.

GREENFIELDBOYCE: In fact, a couple of years ago, when he and a colleague wrote a review of geyser research for a science journal...

MANGA: We could cite just about every paper ever written about geysers, and there's very few fields where you can do that.

GREENFIELDBOYCE: He thinks the mystery is part of the allure of geysers like Steamboat. People like that there are fundamental things about the earth that we still don't understand. Nell Greenfieldboyce, NPR News.