Mt. St. Helen's - After Cycle Updates

[dgavin]

Ok, this might be premature, but going to go ahead and start this off by linking to all the prior BAUT threads about the now quiet volcano.

St. Helen's 2003 -2004 (original) Update thread - Missing in Action

St. Helen's 2004 (Mutant Fly #2 silliness) *Link Updated!

St. Helen's 2004 (Against the Mainstream thread) *Link Updated!

St. Helen's 2005 (Universe Today Article) *Link Updated!

St. Helen's 2005 *Link Updated!

St. Helen's Updates 2006-2008 *Link Updated!

St. Helen's 2006 *Link Updated!

St. Helen's 2007 *Link Updated!

St. Helen's goes to sleep 2008 *Link Updated!

[dgavin]

Well, it's really looking as if St. Helens has gone back to sleep.

Since the USGS Announcement about it returning to slumber in July, earthquake activity has fallen to pre-1980 background levels, with the exception of the fairly continuous rock slide signals.

However this doesn't mean the end of the posts! Coming soon as the information is available I'll be posting on the Post-Eruption erosion patterns, and similar information.

However the cool imagery will not be coming out as often, the USGS is still taking the pictures, but their web site isn't being updated as often with them. (Understandable with all the activity in Alaska they have been concentrating on)

In other Cascade Volcano news, USGS has added more monitoring equipment at the Three Sisters uplift site, and surprisingly at Crater Lake. I suspect the later has more to do with hydrology equipment then seismology, but I haven't found any more details on it other then new equipment was installed.

[BigDon]

I look forward Mr. Gavin.

[dgavin]

Well, St. Helens may be asleep again, but even snoring giants can cause damage.

The Brutus camera was the victim of a rock slide.

Brutus Site Camera...Rest in Pieces

the Glacier toes are still growing and moving, and getting a new infusion of Snow already. Up Close and Personal with a Glaicer Toe.

From the Weekly Status report

One party also mapped out the margin of the west arm of Crater Glacier and found that it had advanced 5 to 15 meters along its breadth since July 31, 2008.

Now that is a speedy little glacier! Now that the two glacier toes are merging, we have the potential to see something new, possibly a Small lake/pond forming in the depression behind them.

If this does happen, it can be expected that such a pond will grow in size as the Glacier debris piles up, and eventually erode through the debris dam, and cause a small flash flood into the lowitt falls area. This would really be a cool thing if it does happen, because it would be likely the first small example of the larger versions of this that happened at the end of the last ice age.

Time will tell if watter pooling does start up behind the glaciers, probably next summer, or summer after will show indecators of this or not.

[chrissy]

This will be great to know how rapid a lake/pool will form, thank you dgavin for this update, I will check in to see what occurs from time to time.

chrissy

[redshifter]

Anyone ever been to the Mt. St. Helens National Volcanic Monument? It's spectacular! From the Jonston ridge observation center, you can see how the north side of the mountain collapsed. It's amazing to see how the blast affected the trees, depending on terrain and distance from the mountain.

[Gillianren]

I've been, but not in a long time. Maybe I'll go again next summer.

[Swift]

Anyone ever been to the Mt. St. Helens National Volcanic Monument? It's spectacular! From the Jonston ridge observation center, you can see how the north side of the mountain collapsed. It's amazing to see how the blast affected the trees, depending on terrain and distance from the mountain.

I was there in about 1993. Yes, very very neat.

[chrissy]

I am not that lucky, it would be an expensive trip.

[dgavin]

Updates from USGS on the Cascade Volcano's

Recent Observations:

Volcano seismicity at Mount St. Helens and elsewhere along the Cascades has remained at low levels over the past week.

On November 17, a small swarm of earthquakes was initiated by a M1.8 shock beneath the summit of Mount Hood.

A new data link was established between CVO and the Pierce County Emergency Operations Center in Tacoma to access real-time data streams from two new seismic/deformation monitoring stations located on the west flank of Mount Rainier.

The U.S. Geological Survey and University of Washington continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.

[dgavin]

Glacier Toe still advancing! (Extreamly Hi Def) Looks like it has started to overcome the Lowitt Falls ravine.

Will be intresting to see what will be the outcome of that.

At this point I only have a few guesses. The merging Glacier toes will be resplit, or the Ravine will slowly be filled in with rock and ice, later to rebuild itself in an accelerated manner when the ice melts.

[mugaliens]

Anyone ever been to the Mt. St. Helens National Volcanic Monument? It's spectacular! From the Jonston ridge observation center, you can see how the north side of the mountain collapsed. It's amazing to see how the blast affected the trees, depending on terrain and distance from the mountain.

I went in Aug 2007. My family and I spent all day exploring all over the place. Boy were we tired!

[dgavin]

Haven't forgotten about this thread, there just hasn't been a whole lot to report.

Seismograph readings have been steadily declining at St. Helen's, to their current point of almost no activity other then occasional land slides or glacier movement.

Probably the best indicator that the activity at St. Helen's is over.

I have not been able to post any detail on the erosion patterns at Lowit falls as I had promised. USGS has also cut back publishing their regular pictorial and informational updates. Granted it is likely due to them being busy with three Alaskan volcanoes last year, and now Mt. Mayon.

Hopefully come spring they will release some back dated imagery of St. Helen's as there hasn't been any since august.

For the rest of the Cascades, it's also been very quiet time geologically. Even Sea-MT. Axial has been quiet. The only news here is that the Three Sisters has a new Broad-Band seismograph that also joined the list of USGS webicroders.

[aurora]

This isn't really geology related, more weather related, but there is a current story about a person that fell into the crater.

Rescue attempts are going on since last night.

[Gillianren]

Hey, they could have worse weather for it. It's only a little overcast up here in Olympia right now, and I don't think it's actually pouring anywhere around here!

[slang]

BBC News: Body recovered

[dgavin]

No new imagry yet, however...

There were two quakes this last week, both 2.2 in magnitude, plus there have been very faint readings of short tearm harmonic tremors, 7 of them today alone. This doesn't indicate she is waking up again, but it's been the first readings like these in almost two years.

[Swift]

September 12 and 13 are the scheduled dates for the next massive eruption, since those are the dates I will be visiting.

[dgavin]

There was in improperly worded VONA notice sent out on the cascade range today (it's details ware blank) , after checking seismographs and web cams, there is an extremely tiny ash plume coming out of the dome today at St. Helen's. It's very tiny, not even reaching the height of the crater walls. I expect the notice was likely about that small plume.

There were also two more longer duration harmonic tremors today on the south face.

Not sure what to exactly make of this yet, as there are no EQ swarms it doesn't appear to be any sort of eruptive behavior. My best guess is this might just be some sort of out-gassing from a gas pocket that had been sealed for some time, or something along those lines.

[jj_0001]

September 12 and 13 are the scheduled dates for the next massive eruption, since those are the dates I will be visiting.

Well, bother, I'll be down in Calabasas (Ca) that week.

[dgavin]

Nothing official yet from USGS. On the 24th a small swarm of earth quakes began and continues around St. Helen's and there was another long term harmonic tremor (lasting around 1.5 hours) today.

Far as i can tell this doesn't appear to be anything odd or worry some, but is just likely post eruption activity. The signals are strongest around the Cedar Flats area and less strong (if registering at all) on the mountain proper, indicating that it's most likely not related to St. Helen's volcanic chimney directly.

[dgavin]

Not sure what to really make of this yet, but the harmonic tremors around the cedar flats area has intensified, in duration, frequency and amplitude today, and are now starting to show up on other siesmographs around the St. Helen's area. There is still a lack of consitant EQ swarms that usualy indicates magmatic activity.

This might still qulify as "Background" activity, so USGS's press release tomorrow should indicate if this is notable or not.

[dgavin]

This mornings update from USGS is late.

The activity on the siesmographs has seemed to have settled back down since yesterday, with the exception of another tremor lasting about 2 hours in the Cedar Flats area again about 3 hours ago.

I'm going to go out on a limb and say this is probably nothing other then post eruption grumblings, though I'd of prefered to have waited for USGS's weekly report.

[dgavin]

Ok, USGS report out and the official word is nothing more then background activity, with a note that some geologists were doing field studies on the dome.

On another note they indicated they are installing addition seismographs and deformation monitoring equipment at Crater Lake. This isn't in response to any seismic event I've seen over the years, so it is likely just they got some budgeting and decided to put equipment on the one mountain that only had a single seismograph.

*edit to add*

The harmonic tremor activity is appearing even fainter on the St. Helens seismographs today. Looking at it I still think a sealed gas pocket rupturing is the best explaination for this seiries of events. I can't think of any other reason then was a VONA notice last week.

[Ara Pacis]

The harmonic tremor activity is appearing even fainter on the St. Helens seismographs today. Looking at it I still think a sealed gas pocket rupturing is the best explaination for this seiries of events. I can't think of any other reason then was a VONA notice last week.

Who fed the mountain beans?

[dgavin]

Nothing but wind storms the last few days at St. Helens. No tremors, no EQ swarms, so what ever was going on in the cedar flats area may be over with.

[dgavin]

USGS report is out an includes no mention of these recent events around the cedar flats area. So backgraound activity, albeit some intresting reading for background activity.

[dgavin]

After so long long being quiet, our sleeping Continental Volcano, St. Helen's, has spoken up. Yesterday it was rocked by a 4.3 magnitude Quake (Felt in Portland, Vancouver and other regional towns) followed by various aftershocks, some of which were also felt. The location was 8km North and about 2-4km depth, close to the Johnston Ridge Observatory. While this appears to be Slip/Fault activity, it was at the exact location and depth of the 5.5 mag that preceded the initial eruptions 30 years ago.

There does not appear to be any indication of volcanic tremors, but It's definitely got peoples attention.

[jj_0001]

After so long long being quiet, our sleeping Continental Volcano, St. Helen's, has spoken up. Yesterday it was rocked by a 4.3 magnitude Quake (Felt in Portland, Vancouver and other regional towns) followed by various aftershocks, some of which were also felt. The location was 8km North and about 2-4km depth, close to the Johnston Ridge Observatory. While this appears to be Slip/Fault activity, it was at the exact location and depth of the 5.5 mag that preceded the initial eruptions 30 years ago.

There does not appear to be any indication of volcanic tremors, but It's definitely got peoples attention.

Any indication if it could be inflation or deflation? I don't know how to read the technical information to know which piece of what slipped which way.

[dgavin]

Any indication if it could be inflation or deflation? I don't know how to read the technical information to know which piece of what slipped which way.

USGS is attributing it to "faults along the seismic zone to slip in response to the magma withdrawal". The withdraw being in the form of the already erupted magma. There is still no indication of any volcanic tremors today, althogh there's been a few more minor after shocks.

St. Heles itself and the surrounding region is not showing any signs of deflation however. This is likely due the the very cyclic nature of the volcano. It's deep magma pool seems to recharge at a rate of every 200 years or so, followed by a 30-50 period of activity. Because of the slower but constant influx of magma at 12-8km depth, there may not be the usual inflation/deflation. The Magma pool may always stay presuraized enough that the ground above is always 'inflated'. Atleast thats my best guess.

It's when the pool at the 12-8km starts to inject Magma into the pool at 2km depth, that there is detectable inflation and volcanic tremors on the mountain.

Intrestingly enough USGS also is saying the the location of the volcano (venting) is related to the stike/slip fault itself. "The fault zone likely exerts control on the location of Mount St. Helens volcano. " I'm not sure but it sounds like this means that if the Stike/Slip fratcutred into a new direction somehow that the volcanic vent in that region might change locations as well.