Vulkaanuitbarsting Mount St.Helens

er was gisteren nog wel een docu op National Geographic op over uitbarstingen van de Stromboli.. Best wel interessant. Van die onderzoekers die op de flanken een kamp op slaan en dan dag en nacht de "wacht" houden om mooie plaatjes te schieten.

Lava breaks surface at Mount St. Helens

SEATTLE (AP) — After weeks of earthquakes and steam eruptions, Mount St. Helens has a new lava dome that could even eclipse the volcano's old one.
The quakes subsided as the new lava emerged Monday and cooled in the open air, suggesting molten rock from deep inside the Earth had found the path of least resistance by going around the old dome, said Jon Major, a hydrologist with the U.S. Geological Survey.

Unlike the dramatic rivers of red-hot lava from Hawaii's volcano, St. Helens' extrusion of new rock was subtle and difficult to see from outside the crater. A lazy plume of steam rose slowly from the mountain for much of Tuesday.

Infrared instruments recorded a surface temperature of nearly 1,100 degrees Fahrenheit, confirming that the second dome consisted of cooling lava rather than old rock which had been pushed upward, said USGS volcanologist Willie Scott.

"The fact that we see stuff at the surface that hot means it's new rock," Scott said.

The last dome-building activity at St. Helens began in the months after its deadly May 1980 eruption and lasted six years. Layers of emerging rock gradually formed a rocky dome nearly 1,000 feet tall at the center of the crater floor. The top of the new dome is almost level with the old one just to the north.

"It's possible this new feature will enlarge and perhaps even dwarf the old dome," said Tina Neal, a USGS geologist.

The mountain had been shaking since Sept. 23, with periods of sharp jolts — up to magnitude 3.3 — occurring as often as four times a minute at the height of seismic activity.

"The inference was that those were breaking a pathway" through rock, Major said.

Explosive eruptions are still possible and often follow lava extrusion, said John Pallister, a volcanologist with the USGS.

The 1980 eruption left 57 people dead, leveled trees for miles around and covered much of the Pacific Northwest with ash. It was "barely a five" on the eight-level Volcanic Explosive Index, Major said.

At this point, scientists believe there is a 10% chance of a level four or larger eruption at the 8,364-foot mountain, he said. The area immediately around the mountain is closed.

Monitoring the gases emitted by lava from Mount St. Helens might provide clues to future eruptions, a British volcano expert reported Thursday.

The isotope content of these gases might indicate whether the next eruption will be a catastrophic blast, as occurred in 1980, according to a paper by Jon Blundy of Bristol University, published in Thursday's issue of the journal Science.

Blundy and doctoral student Kim Berlo studied the gases from magma in the mountain's 1980 eruption and concluded there were two lava reservoirs.

One, located a little more than four miles deep had been shedding gas for five years before that explosive eruption, they said, and a second short-lived reservoir was located nearly two-and-a-half miles deep.

Blundy reported that the magma which erupted in May 1980 came from both the deep and shallow reservoirs. Later, more gentle eruptions, came exclusively from magma trapped at shallow levels.

Mount St. Helens has been rumbling in recent weeks, producing a new lava dome in the crater. Scientists are watching to see if a more substantial eruption will occur.

"We have shown there is a link between the storage depth of magma and the explosiveness of an eruption," Blundy said in a statement.

"This suggests that monitoring the abundance of short-lived radioactive isotopes above restless volcanoes could be a useful tool for predicting the style of the next eruption. It might also provide clues as to when the next eruption will occur," he reported.

New Mount St. Helens lava dome grows

VANCOUVER, Washington (CNN) -- A new lava dome inside Mount St. Helens' crater has sprouted a growth that extends upward nearly 330 feet, U.S. Geological Survey officials said Saturday.

The exposed rock face, with a temperature between 752 and 952 degrees Fahrenheit, casts a red glow that can be seen from the north on clear nights, survey geologist Willie Scott said. Temperatures have spiked at nearly 1,300 degrees.

"It's hot enough to glow, but it's solid," Scott said. "It's not like Hawaii lava. It looks like solid rock ... It's formed this welt, and now it's punched through."

The elongated lava dome spreads southward from the old dome, which was created in the six years after the volcano's cataclysmic eruption of May 18, 1980. Like the old dome, it is made of a volcanic rock called dacite, officials said. The growth has taken place since October 27.

The volcano has been rumbling and spewing steam since late September. Geologists say that activity points to an explosive eruption, though none believe it would reach the intensity of the 1980 eruption that killed 57 people and knocked more than 1,000 feet off the top of the mountain. That eruption also created the current crater.

Molten rock first reached the surface October 11.

CNN) -- Washington state's Mount St. Helens volcano belched a column of smoke and ash nearly six miles high Tuesday evening, leaving a plume visible for more than 50 miles, authorities reported.

Glowing lava was visible inside the mountain's crater after the disturbance, which occurred at about 5:20 p.m. (8:20 p.m. ET). There were no immediate reports of damage or injuries, said Alan Steele, an official with Washington's Emergency Management Division.

Pilots reported the column reached an altitude of about 30,000 feet, the National Weather Service said, but no flights were reported canceled or delayed.

The Weather Service posted ash-fall warnings for the Cascade Mountain foothills of southern Washington after the plume appeared.

"The area that the plume is supposed to go through is pretty much forest land," said Sgt. Tony Barnes of the Clark County, Washington, sheriff's department.

Most of the ash was expected to fall in uninhabited areas of neighboring Skamania County.

"We're concerned that it, of course, has erupted, but it's not to the point where we've mobilized resources up into that area," Skamania County Undersheriff Dave Cox said.

The volcano, located about 45 miles northeast of Vancouver, Washington, has been rumbling and spewing steam since late September.

Geologists say that activity points to an explosive eruption, though none believe it will reach the intensity of the 1980 eruption that killed 57 people and knocked more than 1,000 feet off the top of the mountain.

Monidique

Is dat een recente foto? Damn..die is wel erg 'mooi' en indrukwekkend...

tis vandaag precies 25 jaar geleden dat St.Helens explodeerde

http://vulcan.wr.usgs.gov/Volcanoes/MSH/

Mount St.Helens - 25 Years After the BigBang


MOUNT ST. HELENS NATIONAL MONUMENT, Washington (AP) -- A small Douglas fir breaks up from the ground six miles from the base of Mount St. Helens. In the distance, trees scattered like dropped matchsticks lie in the place they were toppled by a cloud of fragmented rock and ash that exploded from this mountain 25 years ago.

The devastating eruption killed 57 people and an overwhelming amount of plant and animal life. But the barren landscape is now scattered with green, and diverse wildlife has made a home in a vastly different habitat.

As the force of the blast destroyed all in its path, it also carried within it new life -- seedlings carried from the south side landed and began to grow. Seeds continue to arrive via animals returning to the area.

Pine trees, honeysuckle and firs are all growing in the blast zone, without the help of man. Alder, cottonwood and willows also abound in an area once covered with ash and debris.

"There was nothing out here. It's easy to forget it was like that," said Peter Frenzen, monument scientist for the U.S. Forest Service at Mount St. Helens. "The next forest is essentially here. We just have to wait for it all to grow up."

The stunning mountain with the horseshoe-shaped crater in its side rumbled back to life September 23, with shuddering seismic activity that peaked above magnitude 3 as hot magma broke through rocks in its path. Molten rock reached the surface October 11, marking resumption of dome-building activity that had stopped in 1986.

On March 8, it shot ash higher than 30,000 feet, but since then has maintained low-key activity, with wispy smoke regularly floating from the crater. (Full story)

Scientists have said a more explosive eruption is possible at any time. But the threat level has decreased enough to allow visitors back to the Johnston Ridge Observatory five miles from the crater. The observatory, named for a scientist killed in the 1980 blast, reopened May 6 for the first time since October.

"This whole mountain is a research tool," said Jeri Botsford, 54, a volunteer who will tell the story of the mountain to many of the 250,000 people expected to come to Johnston Ridge this summer.



18th May 1980

Mount Rainier - Similar St.Helens event posing a threat



ORTING, Washington (AP) -- In the shadow of Mount Rainier, people go about their lives -- going to shop, going to school, going to work.

One day, though, the routine will be broken by a rumble that sounds like a thousand freight trains. If all works accordingly, sirens will alert the 4,400 residents that they have less than 45 minutes to evacuate -- or be buried by an avalanche of mud and debris tumbling off the flank of the 14,411-foot volcano.

Scientists know Mount Rainier could erupt as Mount St. Helens did in 1980. It could gradually build up and explode, or part of it may collapse. It could happen in 200 years, or it could happen tonight.

"People get burned by these kind of events because they think it can't happen in their lifetime," said Willie Scott of the U.S. Geological Survey.

The agency ranks Mount Rainier as the third most dangerous volcano in the nation, after Kilauea on Hawaii's Big Island and Mount St. Helens. Both are currently active.

Other studies call Rainier the most dangerous volcano in the world -- not just for its explosive potential, but because of the 3 million people who live in the Seattle-Tacoma-Bellevue metropolitan area. At least 100,000 people live on top of Rainier mudflows that have solidified.

Mudflow poses a serious threat for Orting. Two rivers drain off the mountain, hug the town and converge just beyond it, putting Orting squarely in the mountain's strike zone. The town, in fact, was built atop a 500-year-old mudflow that buried the valley 30 feet deep.

Construction crews working on new housing developments for Orting's growing population have dug up massive tree stumps -- remnants of a forest buried there the last time Mount Rainier rumbled.

Yet, the risks did not worry Dawn So when she moved here two years ago. She was just looking for a good place to raise her children and open a quilting store.

"I wanted to have my kids in a better school district, a smaller town," she said. "I like to let them play in the front yard without having to worry about them."

Her family has planned its escape routes, and she's confident they could get to high ground in time. She does not, however, spend much time thinking about Rainier's threat.

"It's such a highly improbable situation," she said. "Disasters can happen wherever you're at."

The risk of catastrophe every couple thousand years has not stopped brisk development, either. But as scientists identified Rainier as a threat in the decades after Mount St. Helens' eruption, government officials and citizens have begun preparing.

Most of the mudflows -- also called lahars -- from Mount Rainier were triggered by an eruption, Scott said. But the most recent, the Electron mudflow that buried Orting 500 years ago, did not seem to follow that pattern.