Wednesday Whatzits

Busy day so I probably won't get to update much as we're busy hosting Dr. Charlie Bacon, geologist for the USGS, here at UC Davis today. Dr. Bacon has written some seminal papers in his career and is probably the foremost authority of the evolution of Crater Lake/Mt. Mazama (speaking of which, >a new geologic map for the Park was recently released) and the caldera-forming eruption. He's also a really nice guy.

If you want to read some of his papers, you might try these:

  • Bacon, C.R., Implications of silicic vent patterns for the presence of large crustal magma chambers, in: D.P. Hill, R.A. Bailey, A.S. Ryall, M.L. Jacobsen, (Eds), Proceedings of Workshop XIX; Active tectonic and magmatic processes beneath Long Valley Caldera, eastern California. Open-File Report - U. S. Geological Survey, U.S. Geological Survey, 1984, pp. 830-850.
  • Bacon, C.R., Gardner, J.V., Mayer, L.A., Buktenica, M.W., Dartnell, P., Ramsey, R.W., Robinson, J.E., 2002. Morphology, volcanism, and mass wasting in Crater Lake, Oregon, GSA Bulletin. 114, 675-692.
  • Bacon, C.R., Persing, H.M., Wooden, J.L., Ireland, T.R., 2000. Late Pleistocene granodiorite beneath Crater Lake caldera, Oregon dated by ion microprobe, Geology. 28, 467-470.

Anyway, I thought I'd add a couple of teases today, sent in by my friend Dr. Ed Kohut. Feel free to add your interpretation in the comments.

Event #1

Event(s) #2

Event #3

I'll try to comment on these later when things settle down.

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A common thread I see is proximity to known magma chambers.

The majority are also deep. Indicating?

Background noise for the first two.

Does not seem more then the normal pattern for the last couple of years. But people sure want something to happen in Yellowstone. The last swarm there took a couple of days to really get going. I would ask this question again tomorrow.

By theroachman (not verified) on 15 Apr 2009 #permalink

Even though I sent the info to Erik, I will not speculate in depth!

The linear trend of small quakes in MT is interesting. I do not know if it corresponds to any structural lineation and it may be just an interesting coincidence. If anything was going on there it would be tectonic and not magmatic.

The Long Valley quake sticks out on the map, but overall the area is very quiet seismically.

Is there anything Bacon isn't good for?

I post the following about Puerto Rico not to raise alarms - but to get an answer. I'd like to dispel my uneducated contemplation that all the earthquakes might signify that there could be a volcano brewing around Puerto Rico.
In the area of the deep Puerto Rico trench and inland - there are earthquakes every day.…

Now, some earthquakes also occur westward of the subduction zone. Usually where you have a subduction zone you have volcanic activity. Does anyone have a good idea of the volcanic history of this subduction zone? Last I checked scientists didn't know why there were so many earthquakes around Puerto Rico. The continuous substantial earthquakes here makes me wonder what is going on. Have there been caldera eruptions along the boundary of the Caribbean plate and the Atlantic plate in the past? And if water from this subducted material from the active Puerto Rican trench reemerges in rising magma - will it be a caldera strength eruption? It seems to me that often the first eruption in a particular area is the worst one. Later smaller volcanoes often grow inside the caldera of the initial caldera. So could there be a caldera eruption in a few thousand years around Puerto Rico? The deep trench would indicate a lot of material has been subducted. Is the daily dribble of 3 magnitude earthquakes off Puerto Rico normal for a subduction zone? Although there are earthquakes there every day - I just counted 11 earthquakes of over 3 magnitude on the section of the map (link above) that took place so far today. Farther north is two more earthquakes over 3 mag that happened so far today. Puerto Rico and its trench are very seismically active and I don't where the volcanic activity is or has or will take place as a result of all this subduction.

As for Yellowstone - I think it is one of the best studied, best imaged volcanoes in the world. It can rise an inch or two a year for thousands of years without erupting. The area has had magnitude 7 earthquakes. Small earthquakes are interesting and useful for better understanding the structure of the magma chamber - but I don't consider them alarming.

Now, onto Mammoth Mountain, Long Valley:
If I have any details or phrases wrong please point them out - this is from memory. Mammoth Mountain area has been producing a new volcano about every two-hundred and fifty years or so. I think something is due to happen - but not immediately. We may see something interesting there in our lifetime maybe after the next massive rupture of the San Andreas.
Does anyone know if there is any correlation or pattern with new volcanoes in the Mammoth Mountains and prior San Andreas quakes? The southernmost part of the San Andreas could snap fairly soon. It is called "10 months pregnant" and "20 months pregnant".

By Thomas Donlon (not verified) on 15 Apr 2009 #permalink

If you want to get excited about earthquake swarms and magma chambers, you could also look at the Matata earthquake swarm which has been going on for a couple of years at the northern end of the Taupo volcanic zone (though Geonet insists it is all tectonic in nature)

and even Taupo itself:

again, supposedly all tectonic in nature.

The San Andreas fault now goes farther to the south than it did yesterday.

I've been checking this page daily to try to get a feel for when the next San Andreas quake will occur. Until today the San Andreas was painted as far as the Salton Sea. Now, this page has a longer overlay for the San Andreas fault.

Put a check into the box on the left side of the page to load the San Andreas overlay. The San Andreas overlay is about 30 miles longer (about 45 kilometers) than it was yesterday.

Regarding Taupo, it is hard to draw the line between tectonic quakes and volcanic quakes because the pressure exerted by magma on an area interacts in complex ways with existing faultlines.

Regarding the concern over activity at Mammoth Mountain and Long Valley being somehow triggered by a San Andreas quake - it was expressed to a machinist acquaintance of mine who once helped install stress monitoring equipment in a Mammoth Mount borehole. One of the seismologists there was wondering what affect a San Andreas quake would have on the volcanic activity at Mammoth mountain. I also recall reading that a big earthquake in Alaska changed some activity at Yellowstone.
So, we will have to wait and see if the next San Andreas quake will cause more activity at Mammoth Mountain.

The quakes off the coast of Oregon and Washington State may be volcanic. I forget the details. There could be underwater volcanic activity there.
I don't know if this may set off the Cascadia fault.

The next two links just talk about general concerns about the power of the Cascadia fault. (I saw no tie-in with the recent earthquake swarms in these pages - but I didn't look too carefully.)

Best to you all.

Tom Donlon

By Thomas Donlon (not verified) on 16 Apr 2009 #permalink

The swarm off Oregon is located on the Blanco Fracture Zone, a transform boundary. The moment tensor solutions (beach-balls) posted by the USGS are strike-slip, as expected. So these quakes would not be related to magmatism.

An impressive sequence none the less.

Thanks for all the comments on my little seismic-event-fest. I just wanted to see how folks might interpret them.

Event 1, the Long Valley quake, wasn't that deep (13.2 km), so it might be in the zone where the magma chambers are believed to sit. However, that whole valley is riddled with faults and the M3.1 event wasn't followed by anything else, so I imagine it is just tectonic.

Event 2, near Yellowstone, just seem to be the ambient tectonic noise of that part of the continent.

Event 3, in Hawai'i, could be more interesting if it affects the eruptions at Kilaeau, although HVO seems to indicate that it hasn't.

I'll try to do posts like this more often ... fun stuff!

Eric, as an addict of volcanoes (and hence your site), I am just dying to hear your take on the 5.0 earthquake on Hawaii Big Island. I've been there and walked the lava flow so I guess I have a personal interest! Is there anything you can tell us, or speculate, about the Hawaii earthquake, given that it's not on a fault line and therefore must have been a BIG underground movement of magma, or a collapse, or ...I dont know!

By Welsh Chris (not verified) on 17 Apr 2009 #permalink