Seismologists believe there's an increased likelihood of a hazardous event at Mount St. Helens due to recent changes in the mountain's seismic activity, and a notice of volcanic unrest was issued Sunday afternoon by the U.S. Geological Survey.
"The key issue is a small explosion without warning. That would be the major event that we're worried about right now," said Willie Scott, a geologist with the USGS office in Vancouver.
The trails on the mountain are closed to climbing as a precaution. Existing climbing permits have been cancelled and Jacks Restaurant and Store has stopped issuing new permits.
Initially, hundreds of tiny earthquakes that began Thursday morning had slowly declined through Saturday.
By Sunday, however, the swarm had changed to include more than 10 larger earthquakes of magnitude 2 to 2.8, the most in a 24-hour period since the last dome-building eruption in October 1986, Scott said.
Some of the earthquakes suggest the involvement of pressurized fluids, such as water or steam, and perhaps magma.
The quakes have occurred at depths less than one mile below the lava dome within the mountain's crater.

http://www.komotv.com/stories/33250.htm

Mount Spurr continued to rumble this week, but scientists at the Alaska Volcano Observatory reported no sign that the 11,070-foot volcano about 80 miles west of Anchorage was about to erupt, according to updates released on Friday.
Seismic listening devices recorded about 90 earthquakes beneath the volcano during the week, all within 18 miles of the summit. Scientists also installed three new seismic stations on the volcano's snowy flanks to help monitor movement of magma deep underground. Three new global positioning system units were also installed to detect whether the volcano's surface starts to swell.
The observatory, which monitors 27 volcanoes along the Aleutian Arc, also reported tremors beneath Mount Veniaminof on the Alaska Peninsula and Shishaldin Volcano on Unimak Island. For more information, and an Alaska volcano atlas, check out
http://www.avo.alaska.edu
http://www.adn.com/alaska/story/5535775p-5470867c.html

HOMER, AK - Scientists have downgraded the Level of Concern code for Augustine Volcano from red to orange today, as seismic tremors have quieted down following Wednesday's two short eruptive explosions.

Background tremors are now similar to what they were in recent weeks, as the Cook Inlet island was slowly building toward an eruption. U.S. Geological Survey volcanologists with the Alaska Volcano Center are keeping the warning code at orange for now, as further eruptions are still considered likely.

Crews of scientists are scheduled to travel today to the island by helicopter and fixed wing plane to take new measurements of the volcano, which sent ash into the air with two explosions early Wednesday lasting several minutes each.


Early-morning blasts from Augustine Volcano gave way to quiet around
Cook Inlet on Wednesday. Later tremors suggested more activity on
the way. Scientists say Augustine is behaving similarly to eruptions in
1976 and 1986, which peaked with explosions that spit ash for hours.

One day after the Alaska Volcano Observatory downgraded the alert status for Augustine Volcano it erupted twice. The ash cloud is expected to cover the southwestern portion of the Kenai Peninsula. So far, the disruptions to air travel have been minor.

I posted too soon. A co-worker's Alaska Airlines flight from Anchorage to Portland was cancelled due to the possibility of encountering ash.

Augustine Volcano erupted for the first time in three days this morning, sending an ash plume 8 1/2 miles into the air.

The eruption occurred at 7:58 a.m. and lasted approximately five minutes, according to officials at the Alaska Volcano Observatory.

An ash cloud was detected, and the National Weather Service has issued an ash fall advisory until 4 p.m. for the southwest Kenai Peninsula, from Anchor Point to Seldovia.

Click here to read the article from the Anchorage Daily News.

"It's continuous," said UW seismologist Steve Malone. "We know there's a lot of rock breaking, and sooner or later something's got to give."
When it does, the result could be small explosions or eruptions, possibly accompanied by an outpouring of lava onto the 925-foot dome that has built up in the crater since the volcano's massive eruption in 1980, scientists say. But the fact that volcanic gases are not escaping from the mountain in high levels means that fresh magma has not been welling up from deep underground, said Willie Scott, a volcanologist at the U.S. Geological Survey's Cascades Volcano Observatory in Vancouver, Wash. And in the absence of new magma, any eruption will not be major.
Scientists say any hazards from a small explosion, eruption or mudflow would be confined to the mountain's unpopulated flanks.
However, it's likely the mountain also will throw up an ash plume, which could kill the engines of any aircraft flying in the area, Scott said. If a plume occurs, the volcano observatory would notify the National Oceanic and Atmospheric Administration and the Federal Aviation Administration, which would reroute air traffic away from the drifting plume.

Convinced the volcano was already going off yesterday, many people around the region called the volcano observatory to report what they thought were eruption plumes. What they really saw were wisps of clouds or dust from rockfalls in the crater, Scott said.
http://seattletimes.nwsource.com/html/localnews/2002049113_sthelens29m.html

http://www.fs.fed.us/gpnf/volcanocams/msh/

Hood:
http://www.pnsn.org/WEBICORDER/webimaps.html
St. Helens:
http://www.pnsn.org/WEBICORDER/GREEN/SEP_EHZ_current.html
Mount Rainier:
http://www.pnsn.org/WEBICORDER/GREEN/RCS_EHZ_current.html

SEATTLE -- Mount St. Helens began rumbling more intensely Wednesday, prompting scientists to raise the eruption warning level and suggest that ash and rock from a blast could land up to 3 miles from the volcano's crater.

Earthquakes ranging from magnitude 2 to 2.5 were coming about four times a minute, possibly weakening the lava dome in the crater of the 8,364-foot mountain, the U.S. Geological Survey said.

Scientists did not expect anything like the mountain's devastating eruption in 1980, which killed 57 people and coated towns 250 miles away with ash. But a small or moderate blast could come in the next few days, they said.

Click here to read the article.

Speaking of volcanoes, NSF is reporting the discovery of an underwater volcano beneath a recently collapsed ice shelf in Antarctica. There were signs of recent activity in the submerged peak, the summit of which lies approximately 900' below sea level. Hope the streaming video link works:

http://www.comcast.net/providers/fan/popup2.html?v=9804443&pl=22322194.xml&config=/providers/fan/config/default.xml

I got an e-mail saying the streaming video link wasn't working, so here's a link directly to NSF's press release:
http://www.nsf.gov/od/lpa/newsroom/pr.cfm?ni=98

This volcano was discovered by researchers investigating the cause of the collapse of the Larsen B ice shelf.

A small earthquake rumbled beneath Mount Hood today but it wasn't related to Mount St. Helens' venting of steam and ash, according to scientists.
"All these volcanoes have a common tectonic setting," said Willie Scott, geologist with the United States Geological Survey Cascades Volcano Observatory, in Vancouver, Wash. "But each system operates quite independently on their own plumbing system and own magma systems."
Preliminary data at the Pacific Northwest Seismograph Network at the University of Washington in Seattle showed that the earthquake was about 2.7 in magnitude, said lab technician John Patrick.
Scott said it was just a coincidence that a quake shook Mount Hood as Mount St. Helens was belching steam and ash.
When Mount St. Helens erupted in 1980, a swarm of earthquakes shook Mount Hood. But the two events likely had different causes, say scientists.
Volcanic activity usually doesn't cause earthquakes in other locations, said Carolyn Driedger, a geologist with the Cascade Observatory.
The quake on Mount Hood this morning was likely tectonic, she said, a result of rocks breaking up due to geologic plates sliding under North America.
Volcanic quakes, on the other hand, are caused by magma rising, or groundwater getting heated, Driedger said.
Small quakes shake Mount Hood each year, said John Ewert, geologist and vulcanologist also at the Cascades Volcano Observatory.
More active is a bulge south of the Three Sisters mountains in Central Oregon. A five-inch bulge has been monitored there since the 1990s.
Magma is occurring at a deep level in that system, said Scott, causing visible changes in topography over a large area.
He said scientists are keeping close tabs on the bulge but haven't had any indication there will be an eruption there any time soon.
http://seattletimes.nwsource.com/html/localnews/2002053601_webhoodquake04.html

Pumping out 50 - 250 tons of sulfur dioxide per day, St. Helens is now Washington's top air polluter. Full story:

http://seattletimes.nwsource.com/html/localnews/2002105397_volcano01m.html