Long Valley Caldera

[dgavin]

It's been quiet... until today...

1.9 2009/04/02 14:12:46 37.516 -118.866 8.2 17 km ( 10 mi) SE of Mammoth Lakes, CA
3.1 2009/04/02 14:11:01 37.516 -118.865 8.0 17 km ( 10 mi) SE of Mammoth Lakes, CA
1.1 2009/04/02 12:42:46 37.600 -118.713 11.4 5 km ( 3 mi) NW of Toms Place, CA
1.0 2009/04/02 10:56:37 37.634 -119.026 5.4 4 km ( 3 mi) W of Mammoth Lakes, CA
1.2 2009/04/02 08:18:29 37.513 -118.864 7.7 17 km ( 11 mi) SE of Mammoth Lakes, CA
3.3 2009/04/02 08:13:45 37.518 -118.865 8.1 17 km ( 10 mi) SE of Mammoth Lakes, CA
2.1 2009/03/30 14:00:43 37.501 -118.867 7.3 18 km ( 11 mi) WSW of Toms Place, CA
1.0 2009/03/29 08:19:59 37.507 -118.884 7.6 17 km ( 10 mi) SSE of Mammoth Lakes, CA
1.5 2009/03/28 16:16:42 37.495 -118.838 10.5 16 km ( 10 mi) WSW of Toms Place, CA

Far to early to say anythign conclusive about them yet, other then that they are not on a known fault location.

[geonuc]

Interesting. I've spent a lot of time around those parts. Long Valley produced quite the eruption 750,000 years ago and laid down some spectacular tuff formations.

[aurora]

Long Valley has had some smaller eruptions that were relatively recent (post the last big eruption).

I've sort of been keeping an eye on it the last few years, and noticed that the quakes have tended to be south of the Caldera. The most recent eruptions were north of the Caldera.


http://lvo.wr.usgs.gov/

During the past 35,000 years, volcanic activity in the region has been confined to the Mono-Inyo Craters volcanic chain. Some 20 small to moderate eruptions have occurred somewhere along the chain in the last 5,000 years

Future eruptions are more likely to occur somewhere along the Mono-Inyo Craters volcanic chain than from the resurgent dome or south moat area within the caldera.

Edited to add, here is a really cool diagram that shows location and time of the recent eruptions:
http://lvo.wr.usgs.gov/MonoInyoEruptions.html

[dgavin]

Four more events today so far.

1.7 2009/04/02 22:12:03 37.501 -118.870 6.4 18 km ( 11 mi) SSE of Mammoth Lakes, CA
2.7 2009/04/02 22:11:13 37.511 -118.870 8.5 17 km ( 11 mi) SE of Mammoth Lakes, CA
1.0 2009/04/02 19:37:50 37.510 -118.880 5.4 17 km ( 10 mi) SSE of Mammoth Lakes, CA
1.0 2009/04/02 15:17:58 37.514 -118.862 6.9 17 km ( 10 mi) WSW of Toms Place, CA

[sarongsong]

LONG VALLEY OBSERVATORY CURRENT STATUS REPORT

Thursday, April 2, 2009 08:39 PDT

Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

The automatic processing system detected seven earthquakes in the Long Valley area since the last update at 9:29 AM on the April 1...The two magnitude 3 earthquakes likely produced perceptible shaking in the Mammoth Lakes area...USGS

Doesn't sound too out of the ordinary, so far...

[dgavin]

Last few days there has been another micro-swarm at Mamoth Lakes. About 10 events a day, all faily weak around 1.2 magnitude average. Nothign really significant to this small of a swarm though.

[sarongsong]

...laid down some spectacular tuff formations.

Tufa?

[TheHalcyonYear]

Doesn't sound too out of the ordinary, so far...

This is what happens when a pot is watched too closely. Every bubble is scrutinized for evidence that the pot is finally coming to a boil.

[geonuc]

Tufa?

No, tuff.

[jlhredshift]

No, tuff.

And when tuff falls into a lake and is cemented by carbonates with fresh water mollusk shells mixed in you have, a very confusing outcrop that looks like someone made concrete a long time before any one was around to do so.

[flynjack1]

Here in New Mexico we have tuff formations that are quite impressive. Volcanic tuff here contains small black volcanic glass pebbles called "Apache Tears".

[dgavin]

There was another earthquake swarm in the LV Caldera Saturday at noon, below Mammoth Mountain of over 30 events, including one short volcanic tremor preceding one of the largest events, and traling off after that event. They occured at depths of 1.5km to 6km, along a ring falut formation centered below the summit. Ring faults are usualy remnent's of caldera collapses or occur around volcanic magma pools and thier vents.

While this is certainly an intresting event, it's not anything to worry about at this point.

[dgavin]

On yesterdays and then todays web-seismographs, there /appears/ to be two seperate, and very long duration, low level volcanic (harmonic) tremors. Most notable in the readings is they appear to have an almost once a minute rythmic chugging, and a once every 5 minute rythmic increase, that lasts for about 30 seconds.

I've missread signatures before, mistaking wind for tremors, but these are showing some definate rythmic signs that wind does not.

There has been no news release or official staments on these hamonic like readings, so please, treat this as appropriate, information from an amatuer.

[dgavin]

Looks like the rythmic increases stoped about 4:16pm PDT, then the rythmic chugging stoped about 4:45pm PDT, finnaly the tremor slowly declined and then stoped around 5:38pm PDT.

Still can find no notices about this, but while it's notable activity, it's likely still considered background levels for a volcanic region, so it may not make it onto any bullitens.

[dgavin]

The Rythmic signatures started back up yesterday about 7am, and ended around the same time in the afternoon, then started back up again this mornign about 7am.

At this point, I'll have to ammend the last two posts as this looks like acitivty caused by man, some sort of drilling activity maybe.

[dgavin]

Same pattern last night and this mornign, similar time frames, definatelly a man made siesmic signature of some kind.