Uncle Sam
10-01-2004, 12:21 PM
At the time, I lived in Tacoma, right outside of Ft. Lewis. My family and I were in Yakima Wa. visiting friends for the weekend when this erupted in 1980. It was about 7 or 8 a.m. when we heard it, then at about 9 or 10 a.m. the ash hit and it blocked out the sun, we got covered. We had to stay there for the rest of the week, because the ash was so thick, nothing worked. We had to wear t-shirts over our faces until we got face masks about 2 days later.
USAToday (http://www.usatoday.com/news/nation/2004-10-01-st-helens_x.htm?POE=NEWISVA)
As Mount St. Helens keeps rumbling and shaking south of Seattle, scientists see no evidence yet that the volcano is headed for a major eruption like the 1980 disaster.
"But I want to emphasize the word 'yet,' " says Jeff Wynn, the U.S. Geological Survey's chief scientist for volcano hazards. (Related graphic: More on Mount St. Helens)
A swarm of small earthquakes minutes apart deep inside the volcano began nine days ago and have ramped up to as high as magnitude 3.3. Scientists said Thursday there's a 70% chance of a dome-building eruption like the most recent one in 1986.
Such an eruption, while small compared with 1980, could spew ash and melon-sized rocks up to 3 miles from the crater, well short of any people or the closest buildings.
That could happen tomorrow, next week or months from now. Despite sophisticated seismic instruments, global positioning system sensors and daily flights over the 8,366-foot peak to measure gases, scientists cannot predict precisely when it will blow.
Nor do they know for sure that the earthquakes of the last week are the remnants of previous eruptions or a potentially dangerous new phase.
"It's like a hibernating bear, you're not quite sure," Wynn says. "He might stretch a couple of times and then go back to sleep before he finally comes boiling out of his cave. And he may not even come boiling out. He may just kind of stumble around and look out the door."
Mount St. Helens has been menacing the Northwest for 700,000 years, geologists say. An eruption 15,000 years ago, for instance, was five times bigger than in the 1980s.
Scientists know from studying the chemistry of magma — molten rock inside the volcano — whether it's old or new and more volatile. But volcanoes don't operate on human time frames. The 1980 eruption killed 57 people, ravaged hundreds of square miles and blew ash over much of the Pacific Northwest. It was part of a trail of events that began with a huge eruption in the 14th century.
Each of those eruptions involved essentially the same reservoir of magma. Over time, it releases unstable gases and tends to flow and become less ballistic, though it still has, as shown in 1986, "a lot of bounce to the ounce," Wynn says.
But a new magma buildup inside the volcano would make scientists "really nervous," he says. "Then we could have a different kind of threat — magma loaded with gas. We could have a lot of explosive stuff."
Officials said at a briefing Thursday from Cascades Volcano Observatory in Vancouver, Wash., that they've seen no signals indicating new magma. Flights have detected no gases being released. The small quakes are confined to the same location, just over a half-mile deep in the lava dome.
Alarmed callers have reported rocksfalling from the crater wall, but the Geological Survey says that's normal this time of year before the ground freezes. Likewise, steam rising from vents in the dome is part of the long-term cooling of rock and not an indicator it could erupt.
Scientists downplayed the threat of flooding from melting snow and ice should seismic action persist through winter. The Cascade Mountains are home to several major volcanoes, including Mount Rainier and Mount Hood, but scientists see little chance that Mount St. Helens could jump-start them.
"We aren't just focused on Mount St. Helens. We keep an eye on all the Cascades," says Cynthia Gardner, the Vancouver observatory's deputy scientist-in-charge. "But we have no evidence that any others have increased seismicity. They aren't connected."
If the volcano is going through another dome buildup like 1986, pressure from magma a mile down is probably causing it. That magma had risen from 6 miles deep in 1998 but never hit the surface. The dome below the crater's rim is 975 feet high. It moved 2 inches north early this week but had stabilized by Thursday.
"Imagine taking a 1,000-foot-high pile of rocks and moving it 2 inches," Wynn says. "For a geologist, that's a lot of energy."
With images of 1980 still fresh — mudflows choking the Columbia River channel and ash paralyzing towns for 250 miles — no one was taking the volcano lightly.
State and federal emergency officials were told to prepare for an eruption. And the Geological Survey said it was too dangerous for two researchers to study water rushing from the crater for signs of magma and called off the plan. The National Weather Service was asked to have its radar ready to track an ash plume.
USAToday (http://www.usatoday.com/news/nation/2004-10-01-st-helens_x.htm?POE=NEWISVA)
As Mount St. Helens keeps rumbling and shaking south of Seattle, scientists see no evidence yet that the volcano is headed for a major eruption like the 1980 disaster.
"But I want to emphasize the word 'yet,' " says Jeff Wynn, the U.S. Geological Survey's chief scientist for volcano hazards. (Related graphic: More on Mount St. Helens)
A swarm of small earthquakes minutes apart deep inside the volcano began nine days ago and have ramped up to as high as magnitude 3.3. Scientists said Thursday there's a 70% chance of a dome-building eruption like the most recent one in 1986.
Such an eruption, while small compared with 1980, could spew ash and melon-sized rocks up to 3 miles from the crater, well short of any people or the closest buildings.
That could happen tomorrow, next week or months from now. Despite sophisticated seismic instruments, global positioning system sensors and daily flights over the 8,366-foot peak to measure gases, scientists cannot predict precisely when it will blow.
Nor do they know for sure that the earthquakes of the last week are the remnants of previous eruptions or a potentially dangerous new phase.
"It's like a hibernating bear, you're not quite sure," Wynn says. "He might stretch a couple of times and then go back to sleep before he finally comes boiling out of his cave. And he may not even come boiling out. He may just kind of stumble around and look out the door."
Mount St. Helens has been menacing the Northwest for 700,000 years, geologists say. An eruption 15,000 years ago, for instance, was five times bigger than in the 1980s.
Scientists know from studying the chemistry of magma — molten rock inside the volcano — whether it's old or new and more volatile. But volcanoes don't operate on human time frames. The 1980 eruption killed 57 people, ravaged hundreds of square miles and blew ash over much of the Pacific Northwest. It was part of a trail of events that began with a huge eruption in the 14th century.
Each of those eruptions involved essentially the same reservoir of magma. Over time, it releases unstable gases and tends to flow and become less ballistic, though it still has, as shown in 1986, "a lot of bounce to the ounce," Wynn says.
But a new magma buildup inside the volcano would make scientists "really nervous," he says. "Then we could have a different kind of threat — magma loaded with gas. We could have a lot of explosive stuff."
Officials said at a briefing Thursday from Cascades Volcano Observatory in Vancouver, Wash., that they've seen no signals indicating new magma. Flights have detected no gases being released. The small quakes are confined to the same location, just over a half-mile deep in the lava dome.
Alarmed callers have reported rocksfalling from the crater wall, but the Geological Survey says that's normal this time of year before the ground freezes. Likewise, steam rising from vents in the dome is part of the long-term cooling of rock and not an indicator it could erupt.
Scientists downplayed the threat of flooding from melting snow and ice should seismic action persist through winter. The Cascade Mountains are home to several major volcanoes, including Mount Rainier and Mount Hood, but scientists see little chance that Mount St. Helens could jump-start them.
"We aren't just focused on Mount St. Helens. We keep an eye on all the Cascades," says Cynthia Gardner, the Vancouver observatory's deputy scientist-in-charge. "But we have no evidence that any others have increased seismicity. They aren't connected."
If the volcano is going through another dome buildup like 1986, pressure from magma a mile down is probably causing it. That magma had risen from 6 miles deep in 1998 but never hit the surface. The dome below the crater's rim is 975 feet high. It moved 2 inches north early this week but had stabilized by Thursday.
"Imagine taking a 1,000-foot-high pile of rocks and moving it 2 inches," Wynn says. "For a geologist, that's a lot of energy."
With images of 1980 still fresh — mudflows choking the Columbia River channel and ash paralyzing towns for 250 miles — no one was taking the volcano lightly.
State and federal emergency officials were told to prepare for an eruption. And the Geological Survey said it was too dangerous for two researchers to study water rushing from the crater for signs of magma and called off the plan. The National Weather Service was asked to have its radar ready to track an ash plume.