Waiting for Death Valley's Big Bang: A Volcanic Explosion Crater May Have Future Potential
23 January 2012
AGU Release No. 12-01
For Immediate Release
WASHINGTON, DC —In California’s Death Valley, death is looking just a
bit closer. Geologists have determined that the half-mile-wide
Ubehebe Crater,
formed by a prehistoric volcanic explosion, was created far more
recently than previously thought—and conditions for a sequel may exist
today.
Up to now, geologists were vague on the age of the 600-foot-deep
crater, which formed when a rising plume of magma hit a pocket of
underground water, creating an explosion. The most common estimate was
about 6,000 years before present, based partly on Native American
artifacts found under debris. Now, a team based at Columbia
University’s
Lamont-Doherty Earth Observatory
has used isotopes in rocks blown out of the crater to show that it
formed just 800 years ago, around the year 1300. That geologic youth
means it probably still has some vigor; moreover, the scientists think
there is still enough groundwater and magma around for another eventual
reaction.
The study was published in the 18 January issue of
Geophysical Research Letters, a publication of the American Geophysical Union.
Ubehebe (YOU-bee-HEE-bee) is the largest of a dozen such craters, or
maars, clustered over about 3 square kilometers (1.2 square miles) of
Death Valley National Park.
The violent mixing of magma and water, resulting in a so-called
phreatomagmatic explosion, blew a hole in the overlying sedimentary
rock, sending out superheated steam, volcanic ash and deadly gases such
as sulfur dioxide. Study coauthor Brent Goehring, now at Purdue
University, says this would have created an atom-bomb-like mushroom
cloud that collapsed on itself in a donut shape, then rushed outward
along the ground at some 200 miles an hour, as rocks hailed down. Any
creature within two miles or more would be fatally thrown, suffocated,
burned and bombarded, though not necessarily in that order. “It would
be fun to witness—but I’d want to be 10 miles away,” said Goehring of
the explosion.
The team began its work after Goehring and Lamont-Doherty professor
Nicholas Christie-Blick led students on a field trip to Death Valley.
Noting that Ubehebe remained poorly studied, they got permission from
the park to gather some 7.5- to 15-centimeter (3- to 6-inch) fragments
of sandstone and quartzite, part of the sedimentary conglomerate rock
that the explosion had torn out. In the lab, Goehring and
Lamont-Doherty geochemist Joerg Schaefer applied recent advances in the
analysis of beryllium isotopes, which change their weight when exposed
to cosmic rays. The isotopes change at a predictable rate when exposed
to the rays, so they could pinpoint when the stones were unearthed. An
intern at Lamont-Doherty, Columbia College undergraduate Peri Sasnett,
took a leading role in the analysis, and ended up as first author on
the paper.
The dates clustered from 2,100 to 800 years ago; the scientists
interpreted this as signaling a series of smaller explosions,
culminating in the big one that created the main crater around 1300. A
few other dates went back 3,000 to 5,000 years; these are thought to
have come from earlier explosions at smaller nearby maars.
Christie-Blick said the dates make it likely that magma is still lurking
somewhere below. He pointed out that recent geophysical studies by
other researchers have
spotted what look like magma bodies under other parts of Death Valley.
“Additional small bodies may exist in the region, even if they are
sufficiently small not to show up geophysically,” he said. He added
that the dates give a rough idea of eruption frequency: about every
thousand years or less, which puts the current day within the realm of
possibility. “There is no basis for thinking that Ubehebe is done,”
Christie-Blick said.
Hydrological data points the same way. Phreatomagmatic explosions
are thought to take place mainly in wet places, which would seem to
exclude Death Valley – the hottest, driest place on the continent. Yet,
as the researchers point out, Lamont-Doherty tree-ring researchers
have already shown that the region was even
hotter and drier during Medieval times, when the blowup took place.
If there was sufficient water then, there is certainly enough now,
they say. Observations of springs and modeling of groundwater levels
suggests the modern water table starts about 500 feet below the crater
floor. The researchers’ calculations suggest that it would take a
spherical magma chamber as small as 90 meters (300 feet) across and an
even smaller pocket of water to produce an Ubehebe-size incident.
Park officials are taking the study in stride. “We’ve typically
viewed Ubehebe as a static feature, but of course we’re aware it could
come back,” said geologist Stephanie Kyriazis, a park education
specialist. “This certainly adds another dimension to what we tell the
public.” About a million people visit the park each year. The
scientists note that any reactivation of the crater would almost
certainly be presaged by warning signs such as shallow earthquakes and
opening of steam vents; this could go on for years before anything
bigger happened.
For perspective, Yellowstone National Park, further east, is loaded
with explosion craters made by related processes, plus the world’s
largest concentration of volcanically driven hot springs, geysers and
fumaroles. The U.S. Geological Survey expects an explosion big enough
to create a 300-foot-wide crater
in Yellowstone about every 200 years; there have already been at least 20 smaller blowouts in the past 130 years. Visitors sometimes are
boiled alive in springs,
but no one has yet been blown up. Death Valley’s own fatal dangers are
mainly non-geological: single-vehicle car accidents, heat exhaustion
and flash floods. Rock falls, rattlesnakes and scorpions provide extra
hazards, said Kyriazis. The crater is not currently on the list. “Right
now, we’re not planning to issue an orange alert or anything like
that,” she said.
Notes for Journalists
Journalists and public information officers (PIOs) of educational
and scientific institutions who have registered with AGU can download a
PDF copy of this paper in press by clicking on this link:
http://dx.doi.org/10.1029/2011GL050130
Or, you may order a copy of the final paper by emailing your request to Kate Ramsayer at
kramsayer@agu.org. Please provide your name, the name of your publication, and your phone number.
Neither the paper nor this press release are under embargo.
Title:
“Do phreatomagmatic eruptions at Ubehebe Crater (Death Valley, California) relate to a wetter than present hydro-climate?”
Authors:
Peri Sasnett: Department of Earth and Environmental Sciences,
Columbia University, Palisades, New York, USA, and Lamont-Doherty Earth
Observatory, Earth Institute at Columbia University, Palisades, New
York, USA;
Brent M. Goehring: Department of Earth and Environmental Sciences,
Columbia University, Palisades, New York, USA, Lamont-Doherty Earth
Observatory, Earth Institute at Columbia University, Palisades, New
York,USA, and Department of Earth and Atmospheric Sciences, Purdue
University, West Lafayette, Indiana, USA;
Nicholas Christie-Blick and Joerg M. Schaefer: Department of Earth
and Environmental Sciences, Columbia University, Palisades, New York,
USA, Lamont-Doherty Earth Observatory, Earth Institute at Columbia
University, Palisades, New York, USA.
Contact information for the authors:
Peri Sasnett, Email:
peri.sasnett@gmail.com
Brent Goehring, Telephone: +1 (765) 496-2790, Email:
bgoehrin@purdue.edu
Nicholas Christie-Blick, Email:
ncb@ldeo.columbia.edu
Joerg Schaefer, Email:
Schaefer@ldeo.columbia.edu
Pollution in China's southern region of Guangxi sparked panic buying of
bottled water this week after a mining firm dumped toxic cadmium into a
river, state media said Thursday.
Residents in Liuzhou city filled shopping carts with boxes of bottled
water, as the government sought to reassure people that the drinking
water supply was safe, Shanghai's Oriental Morning Post reported.
ESA satellites show that a large dome of fresh water has been building
up in the Arctic Ocean over the last 15 years. A change in wind
direction could cause the water to spill into the north Atlantic,
cooling Europe.
The results are remarkable: since 2002, the sea surface in the studied
area has risen by about 15 cm, and the volume of fresh water has
increased by some 8000 cubic km - aroun
Extraordinarily cold temperatures in the winter of 2010/2011 caused the
most massive destruction of the ozone layer above the Arctic so far: The
mechanisms leading to the first ozone hole above the North Pole were
studied by scientists of the KIT Institute of Meteorology and Climate
Research (IMK).
According to these studies, further cooling of the ozone layer may
enhance the influence of
As Asia's ethnic Chinese sit down for lavish banquets to usher in the
Lunar New Year, a delicacy long considered a must at celebratory meals
is fast disappearing from menus and dinner tables.
A growing number of shops, restaurants and hotels have in the past few
months given up selling shark fin, which in Asia is usually eaten in
soup, throwing a lifeline to the marine predator that activist
