Yellowstone volcano is expected to erupt again but geologists cannot pinpoint the date or the type of the next blast. Yellowstone last erupted about 70,000 years ago in what was a relatively minor volcanic eruption. The last major, caldera-forming blast occurred about 640,000 years ago and formed the volcano’s recognisable landscape today. However, according to USGS scientist Jake Lowenstern, the uncertainty around Yellowstone means it could erupt next year or it could erupt 1,000 years from now.
Dr Lowenstern said of the next eruption at a 2014 lecture: “There’s an outside possibility that it will be one of these super-eruptions but that’s by no means the most likely scenario.
“As I said before, it’s perfectly possible there never will be another super-eruption out of Yellowstone.
“We’ll get one somewhere on Earth but Yellowstone’s already had three pretty big eruptions and most of these volcanoes don’t have four or five.
“They kind of use up all of the crust that’s available to melt and they lose their ability to keep creating really big eruptions.
“So more likely is we’ll have more of these big lava flows coming out, sort of using up what magma is down there but nobody can tell you for sure.”
Yellowstone volcano’s three biggest eruptions occurred respectively 640,000, 1.3 million and 2.1 million years ago.
Each of the cataclysmic blasts shaped and transformed the surrounding landscape in what is modern-day northwest America.
Since then, the USGS has found evidence of at least 80 non-explosive eruption events, 27 of which produced rhyolite lava flows in the Yellowstone caldera.
Another 13 lava flows broke out beyond the volcano’s caldera and 40 produced so-called basalt vents – volcanic fissures oozing dark and scorching volcanic rock.
For Yellowstone to undergo another super-eruption in the future, it would need to produce more than 240 cubic miles (1,000 cubic km) of material.
All of that molten rock then needs to concentrate in point, a sponge-like magma chamber, and has to exceed 50 percent of all material in the chamber.
Mr Lowenstern all magma chamber imaging and predictions show there is only around 15 percent of melt in Yellowstone’s chamber, compared to solid rock and crystal.
He said: “So it’s possible there are some highly molten areas down there but they’re probably not enormous.
“So we don’t think there’s a big enough area with highly melted regions that could create one of these big eruptions but there could be smaller areas.
“There are probably areas down there that could erupt if the right circumstances forced it.”
When Yellowstone volcano does erupt again in the future, the USGS expects the blast to be a hydrothermal and not explosive one.