Mount Redoubt Volcano

[PetersCreek]

As of 3:50 PM AKDT, the NWS cancelled today's ashfall advisory for the Susitna Valley.

[dgavin]

The web cam evidently did Survive, and they got a brief image before it shut down again. I suspect it's the transmitter site and not the web cam sites that been affected by the eruption.

If they managed a fly by today, they don't have images available from it yet.

From the image:

I'm now placing the VE index at 3. So not a major eruption as compared to St Helen's.

There does not appear to be any evidence of either a Pyroclastic Flow or Pulse.

There is strong evidence of small Lahar's (mud flows) as seen in the lower portion of the image.

The area of the HUT-Camera got a nice dusting of ash, at it's 7km distance from the summit. But not really a surprise.

*edit to Add* According to the standard VE index of plume heights it might be rated as a VE 5. I'm rating it lower as it did not seem to be as explosive as St. Helen's

Images used by courtesy of USGS/AVO public usage rights

[dgavin]

I have a snack for everyone, it's a large 42mb raw video footage of Redoubt on the 21st.

I do NOT know how long this link will be good for.

ftp://ftpext.usgs.gov/pub/wr/ak/anch...9/DSC_0141.AVI

[jlhredshift]

Latest update:

2009-03-24 03:08:02

Seismicity has remained unchanged for the past few hours.

Ash from the 7:41PM AKDT March 23, 2009 explosion is still drifting in the atmosphere. A National Weather Service ashfall advisory remains in effect: http://pafc.arh.noaa.gov/volcano.php

Images from yesterdays's field observations can be found here: http://www.avo.alaska.edu/images/recent_images.php

[dgavin]

Got some inages of the First Look at Summit since the five eruptions, plus last nights eruption sequence (#5) caught on web cam!

WebCam Mar 23 2009, 19:04:11 AKDT
WebCam Mar 23 2009, 19:55:58 AKDT
WebCam Mar 23 2009, 20:43:47 AKDT (First Summit View)

Although still blurry, there are definately some changes noticable at the summit, such as the V shape carved out of what used to be an almost flat ridge line between the summit peeks. There might be other changes as well but the ash cloud remnant is obscuring some of the peek formations.



Changes since the 5th blast:

Seismic activity has tapered off since then, becoming almost flat and silent for a few hours today, only to be now followed by a low level harmonic tremor signature.

USGS isn't saying yet, but it appears that Redoubt has basically cleared its throut, and now magma is likely on the move again. I'm still convinced we are seeing the start of the eruptive events, and there will be more to come down the road.

[PetersCreek]

Not today please. I don't like the look of the winds-aloft plots.

[jlhredshift]

still red

2009-03-25 03:15:45

There has been little change in overall seismic activity over the last several hours. Small discreet events are still occurring. The Aviation Color Code remains at RED, and we are still watching the volcano closely for any sign of renewed explosive activity.

[dgavin]

Possible small (less then VEI 1) steam/ash eruption in the last hours showing on the siesmographs.

VAN/VONA alert

2009-03-25 05:53:13 - VAN/VONA

A small explosion occurred at Redoubt volcano at 05:12 AKDT (1312 UTC). The cloud height is estimated to be about 15,000 ft and is drifting north to northwest of the volcano. The event lasted about 10 minutes.

[dgavin]

Another simillar small Eruption at 10:17 AKDT this morning.

Peters, these are small so shouldn't be any ash fallout worries for you.

[PetersCreek]

Nope, the last report I checked had ashfall projected north to northwest and then, only in the immediate vicinity of the volcano.

[jj_0001]

Interesting. Sanford has popped up as condition undetermined on the volcanoes.usgs.gov site. I have no idea if this means anything at all, or why it would appear today.

[dgavin]

Interesting. Sanford has popped up as condition undetermined on the volcanoes.usgs.gov site. I have no idea if this means anything at all, or why it would appear today.

AVO report from 3/20 on Sanford.

For the past several days, residents of the Copper River Basin have observed and reported a persistent, white cloud streaming from the summit of Mt. Sanford and extending for up to several tens of miles to the south. The cloud was easily visible in Gulkana Weather webcam images. AVO analysis of satellite images over the last several days shows that similar clouds have been intermittently streaming from many of the higher mountain peaks in the Wrangells. These clouds are a weather phenomenon and not related to volcanic activity. The most likely explanation for generation of these clouds is the rise and cooling of moist air as regional air masses pass over the mountains. Local geopgraphic features and solar radiation on the peaks contributes to the presence of moist air that subsequently condenses to create and feed these clouds.

Mt. Sanford, located 45 miles (72 km) east of Glennallen, Alaska, is a dissected complex shield volcano and the highest volcano (16,237 ft; 4,949 m) in the Pleistocene Wrangell volcanic field. Its south face has a vertical relief (cliff) of over 8,000 feet (2,400 m). This precipitous wall is the source of nearly constant rock, snow, and ice-falls onto the Sanford Glacier, and on occasion these falls produce minor, local vapor plumes. There is no record of historical eruptive activity at Mt. Sanford, and the youngest lava flows are estimated to be 100,000 years old.

It's one of the few volcano's that are still considered 'Extinct'

[dgavin]

USGS Lowered Redoubt back to condition Orange/Watch today.

And had this to say in the report:

Current seismicity at Redoubt is at times suggestive of intermittent lava extrusion at the volcano's summit. However, the existence of a new lava dome has not been confirmed because of poor weather.

So looks like the only interpretation on the eruptions I was incorrect about was the possibility of a pyroclastic flow.

[jj_0001]

AVO report from 3/20 on Sanford.



It's one of the few volcano's that are still considered 'Extinct'

Ok, weather, plain and simple. That's harmless. Well, no more harmful than weather...

[dgavin]

Other then what looks like a land slide event at 10pm last night, the seismographs have been relatively quiet, with intermittent small quakes that don't even show up on the new seismograph.

[dgavin]

She erupted...Again! at 8:34 AKDT.

Condition has be set back to Red/Warning.

This appears to be another large one, likely a VEI 2 to 3 event again.

http://www.avo.alaska.edu/image.php?id=17079

[Swift]

From the AVO:

2009-03-26 11:36:34

Seismic activity has declined since the eruption at 09:24 AKDT this morning. Additional ash emissions may occur and another large eruption remains possible.

The 09:24 AKDT event produced a mudflow down the Drift River.

An ashfall advisory in in effect until 4 PM this afternoon for the western Kenai Peninsula where up to 1/8 of an inch of ash could accumulate. For more details refer to the NWS Redoubt Coordination web page (http://pafc.arh.noaa.gov/volcano.php ).

2009-03-26 10:54:12

The major explosive event that started at 09:24 AKDT has diminished, though smaller emissions may occur, or a larger event resume.

The 09:24 event produced a lahar down the Drift River.

Refer to the NWS Redoubt Coordination web page (http://pafc.arh.noaa.gov/volcano.php ) for latest cloud information.

2009-03-26 09:38:42

A major explosive event occurred at 09:24 AKDT. National Weather Service reports the cloud height to be at least 65,000 ft above sea level. Refer to the NWS Redoubt Coordination web page (http://pafc.arh.noaa.gov/volcano.php ) for latest cloud information.

2009-03-26 09:13:25

The explosive event beginning at roughly 08:34 AKDT is diminishing. The event is much smaller than the events of March 22-23 but larger than the events yesterday morning.


2009-03-26 09:02:55

AVO raised the aviation color code to Red and the alert level to Warning at Redoubt volcano. An explosive event beginning at roughly 08:34 AKDT has produced an eruption cloud to at least 30,000 ft. above sea level. The event seems to be dimishing.

2009-03-26 08:52:50

A new explosive event at Redoubt has just taken place at approximately 8:34 AKDT. The NWS has detected a cloud height of about 30,000 feet based on radar. The Aviation Color Code is being raised to Red and the Volcano Alert Level to Warning.

[Dave J]

They say they'rer gearing up for a gas sampling flight...where do they operate from? The Drift River terminal airstrip already had some lahar damage, and is possibly getting more mudflow action...not a "happy" place (unless you're a geologist )

[dgavin]

They have a Heliport somewhere near by, but not sure where...

Current conditions, there has been an almost continual volcanic tremor for the past hour and a half, with almost as continuous steam (with some ash) emission.

More nice pictures from this mornings eruption: http://www.avo.alaska.edu/image.php?id=17116

As seen from Satellite http://www.avo.alaska.edu/image.php?id=17104

Ash-fall at nearby Lodge http://www.avo.alaska.edu/image.php?id=17085
http://www.avo.alaska.edu/image.php?id=17100

Magnified ash from 24th http://www.avo.alaska.edu/image.php?id=17065

[jonfr]

I got this in email few moments ago.

ALASKA VOLCANO OBSERVATORY CURRENT STATUS REPORT
Thursday, March 26, 2009 12:33 PM AKDT (Thursday, March 26, 2009 20:33 UTC)

REDOUBT VOLCANO (CAVW #1103-03-)
60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Aviation Color Code: RED
Current Volcano Alert Level: WARNING

A large eruption of Redoubt volcano occurred at 09:24 AKDT (17:24 UTC)
this morning. National Weather Service reports the cloud height to be
at least 65,000 ft above sea level and pilot reports indicated a plume
height of 60,000 ft. Since this event, a few smaller events have
occurred but these did not generate plumes above about 20,000 feet.

The eruption at 9:24 AKDT also produced a lahar in the Drift River
valley that was detected by seismic instruments.

An ashfall advisory is in effect until 4 PM for the western Kenai
Peninsula. High level ash (above 30,000 feet) is forecast to pass over
Anchorage, but is not expected to produce ash fall. For more
information refer to the NWS Redoubt Coordination web page
(http://pafc.arh.noaa.gov/volcano.php) for latest ash cloud
information.

AVO is monitoring the situation closely, the observatory is staffed
24/7, and attempts to overfly the volcano will occur as soon as
possible. More details on this mornings eruption also will be released
on AVO's web page as soon as possible.

I would love to see a helicorders plot of the activity there.

[dgavin]

I got this in email few moments ago.



I would love to see a helicorders plot of the activity there.

Thats a VEI 5!!!!! (Talking St. Helen's strength here).

A fairly significant event.

I guess I has grossly underestimated it earlier...But I was correct in my interpretation earlier this week that a larger eruption was on the way.

Peters? I understand the winds were going south wards for this, but how you all doing there north of it?

Attaching the heliocorder's for you jonfr. First is Sunday's (3/22), Second is the smaller Monday event. I forgot to capture yesterdays 2 small eruptions:/ And the third is todays.

[jonfr]

I have been estimating this eruption to reach (great possibility) a level (http://en.wikipedia.org/wiki/Mount_Pinatubo) that is VEI=6, but based on the latest data that I get here, it might go up to VEI=7 event. However, it is quite hard to say at the moment. I guess that this eruption might end in caldera formation.

Based on the helicorders, there appears to be a huge magma pressure under the volcano. The volcano simply might blow it self to up to pieces. But it is really hard to predict volcanoes, so it might go both ways.

[PetersCreek]

Ashfall was on the western Kenai Peninsula from Port Graham, to Homer, and points north. Upper portions of the ash cloud came over Anchorage but there wasn't to be significant ashfall.

[flynjack1]

Ashfall was on the western Kenai Peninsula from Port Graham, to Homer, and points north. Upper portions of the ash cloud came over Anchorage but there wasn't to be significant ashfall.

Good to hear no problems there yet. Hope the air stays clear for you, but if the predictions of a bigger boom to come are true, dont put the mask away just yet.

[jonfr]

There is a lot of earthquakes happening in the volcano at the moment. It signals in my opinion a pre-cursor for a new eruption in next 5 to 18 hours (from when I write this). Given the earthquake size in the plot, they appears to be ML2,5 to ML3,5 and maybe larger. I also see in this plot a slow and low period earthquakes, but those happens when the magma is pushing up trough the volcano it self.

The online plot can be found here, http://www.avo.alaska.edu/webicorders/Redoubt/

[dgavin]

There is a lot of earthquakes happening in the volcano at the moment. It signals in my opinion a pre-cursor for a new eruption in next 5 to 18 hours (from when I write this). Given the earthquake size in the plot, they appears to be ML2,5 to ML3,5 and maybe larger. I also see in this plot a slow and low period earthquakes, but those happens when the magma is pushing up trough the volcano it self.

The online plot can be found here, http://www.avo.alaska.edu/webicorders/Redoubt/

Actually those are surface quakes of very low intensity. About .5 magnitude. The way to estimate magnitude is to check Mt Spurr's seismographs and other graphs around the area, but not close to Redoubt. If it barely shows up on Spurr, it's about a Mag 2.8. So the VEI 5+ blast today only had a Mag 2.8 or 2.9 event behind it.

The VEI is a bit of a subjective scale.

It's not just the cloud height but the destructive force as well.

A VEI 5 usually always includes a Pyroclastic flow/pulse event.

Redoubt did not have one of those today, which means it was mostly a hydrothermal (steam) event with some ash emission. (it takes a lot of hot ash weight to cause an eruption column to collapse into a pyroclastic flow/pulse).

This is the first time that I think an almost purely steam driven eruption reached a VEI 5. As such I'd not be willing to rate it much higher myself.

I did hypothetically talk about a similar massive steam eruption possibility at Crater Lake years ago on this forum. But that was only idle speculation.

This is really sort of a new happening here, to have basically a succession of eruptions of mostly steam, with some ash. But not a lot of ash.

I wouldn't count out a caldera collapse, but it's not likely yet. That would have certain precursor signals, such as an extended single eruption (blast) lasting from 24 hours to days or even weeks, and massive deformation of the entire region. Surprisingly there has not been much deformation at Redoubt yet.

We're still looking at a mostly, hydrothermal driven set of events here. There are some indications of magma movement, but these appear to be slow, seem to stop for days or weeks, and don't match common eruption patterns.

[William]

This is a link to the AP news release for the eruption.

http://news.yahoo.com/s/ap/20090327/...alaska_volcano

ANCHORAGE, Alaska – Alaska's Mount Redoubt erupted several times Thursday, spewing a more than 12-mile-high cloud that could drop ash on Anchorage for the first time since the volcano began erupting Sunday night.

[jonfr]

Actually those are surface quakes of very low intensity. About .5 magnitude. The way to estimate magnitude is to check Mt Spurr's seismographs and other graphs around the area, but not close to Redoubt. If it barely shows up on Spurr, it's about a Mag 2.8. So the VEI 5+ blast today only had a Mag 2.8 or 2.9 event behind it.

The VEI is a bit of a subjective scale.

It's not just the cloud height but the destructive force as well.

A VEI 5 usually always includes a Pyroclastic flow/pulse event.

Redoubt did not have one of those today, which means it was mostly a hydrothermal (steam) event with some ash emission. (it takes a lot of hot ash weight to cause an eruption column to collapse into a pyroclastic flow/pulse).

This is the first time that I think an almost purely steam driven eruption reached a VEI 5. As such I'd not be willing to rate it much higher myself.

I did hypothetically talk about a similar massive steam eruption possibility at Crater Lake years ago on this forum. But that was only idle speculation.

This is really sort of a new happening here, to have basically a succession of eruptions of mostly steam, with some ash. But not a lot of ash.

I wouldn't count out a caldera collapse, but it's not likely yet. That would have certain precursor signals, such as an extended single eruption (blast) lasting from 24 hours to days or even weeks, and massive deformation of the entire region. Surprisingly there has not been much deformation at Redoubt yet.

We're still looking at a mostly, hydrothermal driven set of events here. There are some indications of magma movement, but these appear to be slow, seem to stop for days or weeks, and don't match common eruption patterns.

The swarm of small earthquakes was followed by a harmonic tremor that did last about two hours. So there is magma pushing it self under the volcano.

I am not sure of the distances, but I find it hard to believe that most of the earthquakes are ML0.5 or smaller. I did however check the map of the sensors to give me an idea of where they are located.

It is always a good idea to keep in mind that volcanoes are unpredictable. No matter how well we monitor them.

[Dave J]

Re: the webcorder plots from last night...before the midnight eruption, there were periodic (about evert couple of minutes) "bumps" on the recorder. Are these what they call "harmonic tremors"? And are these what indicate the magma moving through the rock?

Looks like they "detuned the REF recorder, had a lot of maxxed out red sections yesterda, they're all showing blue now. Still, a 37000 foot plume, something sure popped last night.

I wrote to the AVO, apparently overflights are based out of PANC, but I suspect helo flights likely have a forward staging base, still don't know where. Drift River Treminal would be an increasingly hazardous location, they've already had lahars go into the inlet, damaging the airstrip a bit and getting over some tank berms slightly.

[dgavin]

The swarm of small earthquakes was followed by a harmonic tremor that did last about two hours. So there is magma pushing it self under the volcano.

I am not sure of the distances, but I find it hard to believe that most of the earthquakes are ML0.5 or smaller. I did however check the map of the sensors to give me an idea of where they are located.

It is always a good idea to keep in mind that volcanoes are unpredictable. No matter how well we monitor them.

If you go to the USGS Websites Earthquakes page you can see the events that rated 1.0 Magnitude or larger. There are a few 1.0 to 2.0 events, but not a lot of them.

Volcano Seismographs are -much- more sensitive then standard EQ Seismographs, quite often picking up wind storms causing trees to Sway, and other signals.

Additionally surface quakes on a volcano's summit don't behave the same as a deeper quake. The waves move down the mountain and into the earth in a cone like shape, there is very little lateral movement of the surrounding earth.

Harmonic Tremors are not restricted to just magma moving, they are also caused by geysers and other hydrothermal activity. Yes there is likely Magma moving, that much is known. What isn't evident yet is where the magma is precisely.

Has it made it into the mountain? Is it at the base of the mountain? Deeper? It's still an unknown.

The two hour long tremor appears to be related directly to the eruption, putting that one in the hydrothermal category. Deeper magmatic tremors are also occurring but they have been showing up as lower intensity tremors, and appear on the seismographs with less variation in intensity on them.

This was a extremely large eruption, just the content of it was mostly steam. There was some ash, but not a lot. A very unique event for such a large blast. Like i said, I don't think such a huge steam blast has been recorded before.