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In Death Valley, Ancient Volcano Gives Scientists a Surprise (The Christian Science Monitor)

The scientists involved in the work suggest the precursors for an eruption – a supply of magma and an underground source of water the magma could turn to steam in a flash – may still lurk beneath the nearly 800-foot deep crater.

Ubehebe Craters include over a dozen
volcanoes. (Courtesy USGS) 

Small deposits of groundwater could have survived the arid conditions at the time, and could well exist today, the team suggests. Based on the locations of springs in Death Valley today, the team estimates that groundwater may exist within about 500 feet of the crater floor.

A half-mile-wide crater in Death Valley National Park may represent a more significant volcanic hazard than previously thought, according to a new study – though not enough to cancel your next visit to the park.

The crater, Ubehebe, formed in an enormous explosion between 800 and 2,100 years ago, the research team estimates – far more recently than earlier studies suggest.

Moreover, the scientists involved in the work suggest the precursors for an eruption – a supply of magma and an underground source of water the magma could turn to steam in a flash – may still lurk beneath the nearly 800-foot deep crater.

"We were really surprised by the youthfulness of the eruption," says Brent Goerhing, a paleoclimatologist at Purdue University and a member of the team. "We always had in the back of our heads that it could be young, within the past few thousand years. But we didn't think it could be that young."

The results appear in the Jan. 18 issue of the journal Geophysical Review Letters.

Ubehebe is the largest in a grouping of small craters – all thought to have formed the same way: magma rising through the crust to encounter groundwater. The searing magma instantly turned the water to steam, blasting out the crust above it.

The steam and ejected rock would have risen in an expanding column, only to fall back to the valley floor once it ran out of energy to keep rising. The collapse would have sent a hot flow of material with a consistency of just-mixed concrete spreading in all directions at speeds up to 200 miles an hour. Larger rocks the blast lofted would have pummeled the ground.

Small deposits of groundwater could have survived the arid conditions at the time, and could well exist today, the team suggests. Based on the locations of springs in Death Valley today, the team estimates that groundwater may exist within about 500 feet of the crater floor.

A magma source today, however, may be a bit more difficult to pin down. Geophysicists trying to figure out what's underneath Death Valley have come up with conflicting evidence for the presence of liquid or semi-liquid magma.

In a study published last year, researchers from the University of Texas at El Paso used four independent lines of evidence to infer magma's presence. They estimate the magma is trapped some 15 miles below the valley floor.

The team, led by Musa Hussein, cautions that more work needs to be done to establish whether the magma there is molten or partially molten.