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Based on our current understanding of Redoubt's past eruptions, both historical and from the geologic record, and our analysis of the current episode of unrest, AVO considers the following future scenarios as possible:
1) Failed Eruption: No eruption occurs because magma does not reach the surface. Earthquake activity, gas output, and steaming slowly decrease over several weeks or months. Continued heat flux may cause continued, modest melting of snow and ice on the edifice and subsequent increased, but not hazardous outflow into the Drift River.
2) Eruption similar to or smaller than 1989-90: Unrest continues to escalate culminating in an eruption that is similar to or smaller than the one that occurred in 1989-90. An eruption such as this would likely spread volcanic ash throughout Cook Inlet and other parts of south-central Alaska depending upon the prevailing winds. Communities around the volcano, especially to the east, northeast, and southeast, would likely experience trace to several millimeters (less than 0.4 inches) of ash fall as a result of discrete explosive events. Such events could also generate pyroclastic flows that swiftly melt snow and ice to form mudflows, or lahars, that would likely travel east down Drift River, possibly reaching and flowing into Cook Inlet. If summit lava domes form, as they did in 1989-90, they may repeatedly collapse and generate pyroclastic flows that would likely travel north from the summit crater and form lahars. Smaller lahars could also form in other drainages if hot debris accumulated on other flanks of the volcano. An eruption consisting of multiple explosive events, episodic lava-dome growth and collapse, and lahars may last weeks to months.
3) Larger Explosive Eruption: A significantly larger eruption could occur, perhaps similar to eruptions that are thought to have taken place prehistorically. Such an eruption might involve the production of larger ash clouds, pyroclastic flows on several flanks of the volcano, and larger lahars more frequently reaching Cook Inlet down Drift River and affecting other drainages around the volcano as well.
4) Flank Collapse: The intruding magma or other processes could destabilize a portion of the Redoubt edifice that could result in a large volcanic landslide. At least twice in the last 10,000 years, debris flows generated by such landslides have reached Cook Inlet. It is also likely that a landslide of this type would be accompanied by an eruption. Because of the scarcity of these events in the geologic record, a flank collapse and eruption is considered very unlikely. A flank collapse may be accompanied by visible deformation of the edifice and AVO will be looking for such signs.
Based on all available monitoring data and AVOs knowledge of the volcano, scenario number two, an eruption similar to or smaller than that of 1989-90, appears to be the most probable outcome at this time. We consider one and three to be somewhat less likely, and scenario four to be much less likely.
Comparing the time frame of pre-eruptive activity in 1989-90 (the only other eruption for which seismic data were available) with the current unrest, we would expect such an eruption to begin within the next few days or weeks. It is likely that the onset of an explosive eruption would be preceded by a further increase in seismicity. An explosive eruption would be accompanied by a sharp increase in seismicity. Should earthquake activity or other monitoring data suggest that an eruption is expected within hours, or is underway, AVO would move Redoubt from its current Aviation Color Code ORANGE to RED, and Alert Level WATCH to WARNING.
Seismicity remains relatively unchanged since 3:30 PM AKST yesterday afternoon. It is still well above background.
An AVO gas-measurement and observation flight is currently underway. Clear web camera views currently show a steam plume rising from the area of the 1989-90 lava dome.
Originally posted by Res Ipsa
Do we have a "live" webcam site? still pictures is all I get.
I'm looking for a "Gaza" type cam where we see live moving pictures.
Observers from the gas/observation flight today report continued melting at the summit area. Holes in the ice continue to grow exposing more steaming rock. Volcanic gases continue to be detected. Clear web camera views currently show a steam plume rising from the area of the 1989-90 lava dome.
Seismicity over the last hour has included the reappearance of periods of weak tremor at the summit stations. These signals are much weaker than the episodes from Friday afternoon.
Observers from the gas/observation flight today report continued melting at the summit area. Holes in the ice continue to grow exposing more steaming rock. Volcanic gases continue to be detected.
Geologists monitoring Mount Redoubt for signs of a possible eruption noticed that a hole in the glacier clinging to the north side of the volcano had doubled in size overnight — and now spans the length of two football fields.
Scientists with the Alaska Volcano Observatory on Friday flew close to Drift Glacier and spotted vigorous steam emitted from a hole on the mountain. By Saturday, they had confirmed the area was a fumarole, an opening in the earth that emits gases and steam, that was increasing in size at an alarming rate.
They also saw water streaming down the glacier, indicating heat from magma is reaching higher elevations of the mountain.
"The glacier is sort of falling apart in the upper part," research geologist Kristi Wallace said.
The signs of heat add to concerns that an eruption is near, which could send an ash cloud about 100 miles northeast toward Anchorage, the state's largest city, or onto communities on the Kenai Peninsula, which is even closer to the mountain on the west side of Cook Inlet.
Originally posted by violet
reply to post by Blaine91555
Sounds like it won't be too bad then, as long as nobody ventures out unprotected and it isn't one of the other scenarios they thought might happen. Have they said anything on that? Or still saying it will probably be like the '89 one?
Seismic unrest continues at Redoubt. Seismic activity is still well above normal background levels and is holding steady.
Originally posted by Blaine91555
Our worst scenario would be if it shuts down the natural gas supply from that area. All our electricity is generated by it. No electricity or natural gas, means no heat. We just had the longest, worst cold spell in recorded history, following the third coldest summer and it looks like the rest of winter will be extra cold. We are staying right now 10 to 20 degrees (Fahrenheit) below normal nearly every day. No heat would mean frozen pipes everywhere and all sorts of problems.
The largest impact to infrastructure is the possibility of damage and loss of production capability to natural gas wells and transmission facilities from ashfall. Anchorage is supplied with natural gas for power generation from two sources, the Beluga Gas Fields and the Drift River area production platforms in the Cook Inlet. Turbine compressors could be damaged or need to be shut down and would stop the transmission of natural gas to power generation facilities. This lack of power generation would affect the entire Anchorage area.
Another area of concern is the Drift River Oil Terminal located just northwest of Redoubt volcano in the drainage area of the Drift River into the Cook Inlet. Marine Safety Detachment Kenai reports that the Drift River Oil Terminal is a manned facility and has seven 270,000 barrel storage tanks. The facility is accessible only by boat or aircraft.
REDOUBT VOLCANO (CAVW #1103-03-)
60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Aviation Color Code: ORANGE
Current Volcano Alert Level: WATCH
Unrest at Redoubt Volcano continues. Seismicity has remained relatively constant over the last 24 hours and is still well above background. A vapor plume is intermittently visible in the AVO web camera. It appears to rise no higher than the volcano's summit.
An observation and gas-measurement flight to the volcano yesterday noted continued vigorous fumarolic activity and runoff of muddy water down the north flank of the volcano. Volcanic gas was detected; data analysis is ongoing to compare these measurements with previously measured gas output.
Staff are currently monitoring the volcano 24 hours a day. We will issue further information as it becomes available.
Originally posted by Shirakawa
Latest status report
A vapor plume is intermittently visible in the AVO web camera. It appears to rise no higher than the volcano's summit.
Weather conditions are clear at the volcano and a vapor plume is visible rising above the summit crater.