Alaska - Mt Redoubt Volcano could erupt within days

If I remember correctly, Mt St. Helens got really quiet for a day or 2 before it blew it's top to the point where people were demanding to be able to return to their homes. I think it's fairly common for volcanos to show reduced activity once the magma has risen as far as it. At that point it's just a matter of how long will the pressure build up before it blows it's top or melt eventually contacts magma resulting in an explosive event.

The platform webcam shows a small but dense dark cloud coming off the summit of mt.Redoubt. I wonder if it's only steam. The volcano appears to be partially darkened by either dark ash or cloud shadow, in my opinion.

[edit on 2009/2/26 by Shirakawa]

reply to post by pantangele


LOL. I always say I wish we could bet ATS points. I wager 2 more days.
second line

It seems that USGS is saying that Redoubt can sit around a few months making some noise.

I wonder how they determine these things?

volcanoes.usgs.gov...

Optical illusion? Seems like something red with steam coming off it on the right side of the mountain.

Edit: By the time I linked to the image the "steam" was revealed to be a cloud. Appears to just be some optical artifact.

[edit on 26-2-2009 by pantangele]

Update from AVO

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. No eruption has occurred.

Beginning yesterday afternoon at 3:37 PM AKST, tremor amplitude increased sharply and remained elevated for approximately one hour. At 4:14 PM AKST, the tremor amplitude briefly matched the highest amplitude seen during the current episode of unrest. This tremor was strong enough to be recorded on all seismic stations on Redoubt Volcano as well as many stations surrounding Cook Inlet. Since that time, tremor amplitude has decreased significantly. Last night around 10:40 PM AKST, the number of discrete earthquakes increased and remained elevated until about 2:55 AM AKST today. Preliminary analysis of these earthquakes indicate they are occurring at shallow depth (1 to 3 km) below the summit crater of Redoubt. Since that time, discrete events are continuing at a lower rate, and tremor levels remain low. These variations in the character of seismic activity indicate that conditions have changed at shallow depths beneath the volcano. AVO is currently analyzing this seismic activity and will issue further information as it becomes available.

An observation flight to the volcano is currently underway. Winds are too high at the volcano to perform gas measurements today.

A small steam plume is visible in clear HutCam images today.

AVO continues to monitor Redoubt Volcano closely, and the observatory is staffed 24 hours a day.

[edit on 2009/2/26 by Shirakawa]

She just started shaking a good bit! Think this is gonna be the big one, or will we have to wait even longer?...

Wish I could get GEE working to view it in real time...

Looks like something is up. They mention "vigorous steaming" during the flyover today. If nothing else Redoubt has not gone back to sleep.

Go check the activity page now!

The HIGHEST peak on the webicorder since late January AND web camera # 2 (CI) "appears" to show red lava at the base. I could be wrong about the lava - perhaps it's some sort of camera anomoly or whatever. I saved the picture anyway.

Is she seething?

Edit Update - I meant RSAM not webicorder and I later noticed it wasn't new news to ATS. Sorry.

Also, AVO replied and politely agreed that is was camera anomoly that I saw. Second sorry.

[edit on 27-2-2009 by Trexter Ziam]

UPDATE!
Looks like the lava I saw might be the "flow deposit" they mentioned!
Now, what is a "flow deposit"?

Redoubt Volcano has not erupted. Volcanic tremor decreased substantially beginning yesterday afternoon. Small discrete earthquakes dominate the seismic activity today.

During an overflight this afternoon, geologists noted vigorous steaming from the base of the 1989-1990 dome and from a melt hole on Drift Glacier.

Seismicity was at a higher level between 17:30 and 18:10 this evening, and a flow deposit and vigorous steam plume was seen on the webcam images. The flow peaked between 17:52 and 18:04.

AVO is monitoring Redoubt Volcano closely, and the observatory is staffed 24 hours a day.

Edit Update - sorry ... it was not lava that I saw. My mistake.

Also, I checked up "flow deposit" on a University webpage on volcanology and the term seems to be used in association with the lava flow after a "dome collapse". Now I wonder if the dome burst without an eruption or what? Do you get flow deposits prior to an eruption? Maybe an ATS volcanologist can explain it. Thanks!

[edit on 27-2-2009 by Trexter Ziam]

Originally posted by Trexter Ziam
UPDATE!
Looks like the lava I saw might be the "flow deposit" they mentioned!
Now, what is a "flow deposit"?

I'm not 100% sure, but judging by the current volcano status I think they mean "debris flow deposit". This is from the glossary section on their website:

debris flow
A mixture of water-saturated rock debris that flows downslope under the force of gravity (also called lahar or mudflow).

reply to post by Shirakawa


They have now clarified their use of the term "flow". It was a "mudflow".
Mystery solved. Thank you Shirakawa! A mudflow just isn't as exciting as a lava flow.

Redoubt Volcano has not erupted. Seismicity during the past 24 hours has consisted mostly of small discrete earthquakes. A tremor event between 17:30 and 18:10 yesterday evening occurred when a small mudflow and vigorous steam plume could be seen in the webcam images, emerging from one of the ice holes on the mountain's upper north flank. The flow peaked between 17:52 and 18:04.

During an overflight yesterday afternoon, geologists noted steaming from the base of the 1989-1990 dome and from a melt hole on Drift Glacier.

AVO is monitoring Redoubt Volcano closely, and the observatory is staffed 24 hours a day.

www.avo.alaska.edu...

By the way, I discovered something strange occurring on REF seismic station that is not normally visible on its webicorder. This is the question I sent to the AVO staff, I hope it will get answered:

Hello,

First of all, I have to congratulate with you all for the great work you're doing with Redoubt volcano coverage.

This is my question: I have downloaded via VASE (a tool from IRIS) a 5 hour long seismogram trace of AV.REF seismic station from today (2008-02-17 11:00-16:00 UTC), EHZ channel, and, with a simple tool I made, converted it to audio. I then opened the resulting wave file in a audio editing program to hear it (sped up to audible frequencies) and make a spectrogram of its trace.

I found out a strange anomaly in various sections of the trace: an irregular whistle (so it sounds at 8000 hz, at 80x speed of the original 100 hz sample rate) which decreases or increases in pitch over time (depending of when you start to hear). Actually there are many of them, and sometimes they overlap one each other (two or more whistles of increasing and/or decreasing tone can be heard at the same time).

This anomaly is not very strong, but it's clearly visible on the EHZ vertical channel. It's much less visible on the EHE channel, and almost invisible on the EHN channel. It doesn't seem to show up on other seismic stations and it's not an artifact caused by the audio conversion. What is it?

Please have a look at this annotated screenshot of the spectograms of the first two hours of the trace I downloaded for REF seismic station, EHZ, EHE and EHN channels:
Large image link (2 megabytes)

Thanks in advance for your time,
SHIRAKAWA Akira

In the meanwhile, here's another bihourly update from AVO:

2009-02-27 08:32:22
Redoubt Volcano has not erupted. Seismicity during the past 24 hours has consisted mostly of small discrete earthquakes.

The Hut web cam will be turned on later this morning.

Field work planned for today includes a gas measuring flight and installation of temporary GPS receivers.

AVO is monitoring Redoubt Volcano closely, and the observatory is staffed 24 hours a day.

[edit on 2009/2/27 by Shirakawa]

reply to post by Shirakawa


Thanks for all your hard work and to other's contributions as well. I'm not able to get online much, so just trying to catch up a bit ... I see it still hasn't blown.

Here's the latest from AVO

2009-02-27 11:14:33

Activity at Redoubt Volcano continues. The volcano has not erupted. Seismicity consists mostly of small discrete earthquakes.

The web cams show clear views of the volcano this morning. The dark area on the north flank of Redoubt in the HUT web cam image appeared during a brief episode of strong tremor late yesterday afternoon. The dark area is evidence of a water rich flowage event coming from Drift Glacier.

AVO

An AVO member answered my question about that anomaly I found on a seismograph trace from REF seismic station (personal details have been removed):

Those signals aren't terribly uncommon, and are visible occasionally on a variety of our stations and several different volcanoes. They typically last from hours to months, and warble up and down slowly in the higher frequency ranges. They represent some sort of electronic noise in the system, rather than an actual signal from the volcano. Because they're a signal that is generated within the electronics of a station, you'll see them strongly only on that one station --and possibly on all the channels associated with that station. On sick stations, sometimes they're the only obvious "signal", and certainly sound interesting (I too, often speed up seismic signals in order to be able to listen to them).

Weekly update from AVO:

ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, February 27, 2009 1:31 PM AKST (Friday, February 27, 2009 22:31 UTC)

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. No eruption has occurred.

Relatively low-amplitude volcanic tremor and intermittent discrete earthquakes characterized seismic activity at Redoubt from February 21-24. During this time, clear weather allowed many web camera and satellite views that showed nothing out of the ordinary.

On Wednesday, February 25, a broad-spectrum seismic signal at 9:29 AM AKST was likely associated with a small mud flow originating from a melt hole in the Drift glacier at about 5600 feet above sea level. This dark deposit was seen in a web camera image from 10:03 AM AKST that morning, and observers on an overflight the next day reported that the deposit was several hundred meters in length. Later the same day, at 3:37 PM AKST, tremor amplitude increased sharply and remained elevated for approximately one hour. This tremor was strong enough to be recorded on all seismic stations on Redoubt Volcano as well as many stations surrounding Cook Inlet. At 10:40 PM AKST the same night, the number of discrete earthquakes increased and remained elevated for about four hours.

On Thursday, February 26, a flurry of earthquakes began at 5:30 PM AKST and lasted for roughly one hour. These events were accompanied by the emplacement of a mudflow that covered a large portion of the upper Drift glacier, as viewed in web camera images beginning at 6:04 PM AKST. An ASTER thermal infrared satellite image from last night shows this deposit stretching several kilometers down the Drift glacier.

The recent variations in seismic activity coupled with increased melt water discharge on the upper Drift glacier indicate that conditions have changed at shallow depths beneath the volcano. It is possible that magma has moved to shallower levels in the volcanic edifice, but recent changes may be due instead to changes in degassing pathways from a deeper magma body. AVO is currently analyzing this seismic activity and will issue further information as it becomes available. A gas-measurement flight is currently underway.

Because of the clear weather this past week, AVO was able to undertake several flights to Redoubt to measure gas (February 21, and today) and perform upgrades to the monitoring network (February 21, 22, and today). Results from the February 21 gas flight reveal that the emission rates of CO2 and SO2 have not changed since February 7 and both remain high. Upgrades to the network include addition of a broadband seismometer on the volcano's west flank, installation of a pressure sensor (to detect airwaves) north of the volcano, and improvements to the power supply at the AVO hut.

AVO continues to monitor Redoubt Volcano closely, and the observatory is staffed 24 hours a day.

Heavily ice-mantled Redoubt volcano is located on the western side of Cook Inlet, 170 km (106 mi) southwest of Anchorage and 82 km (51 mi) west of Kenai, within Lake Clark National Park. Redoubt is a stratovolcano which rises to 10,197 feet above sea level. Recent eruptions occurred in 1902, 1966-68, and 1989-90. The 1989-90 eruption produced mudflows, or lahars, that traveled down the Drift River and partially flooded the Drift River Oil Terminal facility. The ash plumes produced by the 1989-90 eruption affected international air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other nearby communities.

[edit on 2009/2/27 by Shirakawa]

A 3.7 centered near Redoubt just hit.

The epicenter was 70 kilometers away from the volcano, so It's probably not related to its current unrest.

I managed to obtain a list of earthquakes occurred beneath redoubt volcano and tried to compute the moving average of the depth of each earthquake. This is what I obtained:


(Warning: the X axis is not time-proportional)

It seems to me that earthquakes tend to become deeper over time. I don't know if it's a good or bad thing.

It has been quiet for a few days now, maybe it is the calm before the show. I am thinking that an eruption is NOT iminent anymore.