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Quakes at Yellowstone 3 January 2009

Posted by admin in activity reports, calderas, United States, Yellowstone.
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The calderas of the Yellowstone Plateau volcanic field provide a favourite agent of doom for those who like to brood on the destruction of civilization through a catastrophic ‘supervolcano’ eruption. Even leaving aside the supervolcano angle, or at least putting it into perspective (‘The probability of a large caldera-forming eruption within the next few thousand years is exceedingly low’, says the USGS), this is a very active volcanic zone that has seen large-scale eruptive activity over the last two million years. Yellowstone has seen three huge caldera-forming eruptions 2.1 million years ago, 1.3 million years ago and 640,000 years ago, the eruption of extensive rhyolitic lava flows between 150,000 and 70,000 years ago, and several major hydrothermal eruptive episodes during the past 10,000 years. The news of ongoing earthquake swarms at Yellowstone over the past week is thus of great interest.

There is nothing unusual about earthquakes at Yellowstone: the Yellowstone Volcano Observatory (YVO) says that 1-20 earthquakes are normally recorded every day. At times, however, earthquake activity increases significantly, with a rise in the number of earthquakes, all of about the same magnitude (i.e. no distinguishable mainshock or aftershock) occurring over a short period – an earthquake swarm. The YVO relates that recent notable swarms occurred in 1977, 1985, 1995, 1999, and 2004. The latest significant swarm is under way now, and it is the largest since 1985, says the YVO’s top scientist, Dr Jacob Lowenstern.

The current earthquake swarm began on 26 December 2008 with the University of Utah Seismograph Stations recording quakes of magnitudes under 3.5 located beneath Yellowstone Lake. The swarm continued and intensified on 27 December with magnitudes of 2.5 to 3.2, the larger of which were felt by people in the Yellowstone Lake area. On 29 December the YVO reported that more than 250 events had taken place since the swarm began, with the largest quakes up to then registering magnitudes between 3 and 3.9. (Source: YVO updates archive for December 2008.)

On 1 January 2009 the YVO reported that the swarm was continuing:

Yellowstone seismicity increased significantly in December 2008 due to an energetic earthquake swarm that commenced on December 26. This swarm, a sequence of earthquakes clustered in space and time, is occurring beneath the northern part of Yellowstone Lake in Yellowstone National Park. As of this writing, the largest of these earthquakes was a magnitude 3.9 at 10:15 pm MST on Dec. 27. Through 5:00 pm MST on Dec. 31, the sequence had included 12 events of magnitude 3.0 to 3.9 and approximately 20 of magnitude 2.5 to 2.9, with a total of at least 400 events large enough to be located (magnitude ~1 or larger). National Park Service (NPS) employees and visitors have reported feeling the largest of these earthquakes in the area around Yellowstone Lake and at Old Faithful and Grant Village. The hypocenters of the swarm events cluster along a north-south-trending zone that is about 7 km long. The vast majority of the focal depths are shallower than 5 km.

By 2 January more than 500 earthquakes had been recorded with depths ranging ‘from ~ 1km to around 10 km’ and the activity showing a northwards migration. The YVO sees no cause for concern in this earthquake swarm, but warns that ‘there is some potential for hydrothermal explosions and earthquakes may continue or increase in magnitude. There is a much lower potential for related volcanic activity’. (Source: YVO updates archive for January 2009.)

Overall, the message from the Yellowstone Volcano Observatory and the USGS is that this earthquake swarm is within the parameters of normal behaviour for Yellowstone (and indeed the alert level remains at ‘normal‘) and is a product of hydrothermal activity rather than magma movement. To quote Dr Lowenstern of the YVO:

At this point, any kind of volcanic eruption is a long shot … the most likely thing is that the swarm will continue, perhaps for weeks, and then will end without any other related activity … before any kind of an eruption we’d expect a whole lot of change in the ground deformation as measured by GPS. Nothing has changed over the past week.

Predictions of the end of civilization, or even just devastation for America, are premature, it seems.

The latest: Seismic data from the Yellowstone stations for today, 3 January 2009, shows a falling off in intensity since around 21:45 UTC yesterday.

There’s further coverage of Yellowstone developments at Greg Laden’s blog (also here – don’t miss the comments – and an earlier article here), and Dr Erik Klemetti’s Eruptions. For another angle, see Alan Sullivan’s Fresh Bilge. US News & World Report is also paying attention to Yellowstone: see James Pethokoukis’s latest, ‘Earthquakes at Yellowstone Supervolcano: Update’. That’s in the Capital Commerce blog, in the financial section. US News‘s so-called ‘Science’ section doesn’t bother itself about this kind of thing.

News
Scientists watch unusual Yellowstone quake swarm – Associated Press, 29 December 2008
Yellowstone earthquake swarm puzzles scientists – LiveScience, 30 December 2008
Multiple tiny earthquakes rattle YellowstoneScientific American, 30 December 2008
A spurt of quake activity raises fears in YellowstoneTime, 1 January 2009
Earthquake swarm at Yellowstone supervolcano: updateUS News & World Report, 1 January 2009
More small quakes rattle Yellowstone National Park – Associated Press, 2 January 2009
Earthquakes at Yellowstone supervolcano: updateUS News & World Report, 3 January 2009

Information
Global Volcanism Program: Yellowstone – information about the Yellowstone Plateau volcanic field (1205-01-)
Yellowstone Volcano Observatory – monitors activity at Yellowstone
University of Utah Seismograph Stations – UUSS home page, including Yellowstone updates
Yellowstone Region seismogram displays – near real-time seismogram traces for Yellowstone
USGS earthquake list for Yellowstone – constantly updated earthquake data for Yellowstone

The Volcanism Blog

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Comments

1. volcanophile - 4 January 2009

What would be interesting to know is the type of eruption to be expected. It looks like the caldera is a rhyolitic one, which means high viscosity, high gas lava.

Therefore we could end up with something like at Chaitén, a strong initial explosive blast followed by dome growth.

There is something which surprises me a lot in your article, you talk about rhyolitic lava flows… AFAIK, rhyolitic lava is pasty, and piles up on the spot of emission, instead of flowing downslope like basaltic lavas… Are there different types of rhyolite, which can be more fluid, and therefore erupt in a strombolian or hawaian way?

But whatever type of eruption is coming, it’s very very unlikely to be the big one everyone fears… Be realistic, you have better odds of being struck twice by lightning on the same day in the same spot than to witness this kind of event in a lifetime…

2. Pyre - 5 January 2009

“… you have better odds of being struck twice by lightning on the same day in the same spot….”

Especially if you’re standing on a mountaintop during a thunderstorm, in full armor and soaking wet, waving your sword at the clouds and calling Thor a bastard.

Standing up again afterwards, resuming the position, and sneering “You call THAT lightning?!” would probably be indiscreet.

Likewise, if you paddle your boat out into the north end of Yellowstone Lake and start mocking Hephaestus for being a cuckold, then feel your boat go aground and start rising, well, don’t come complaining to me afterwards about your lousy luck.

In this life or (more likely) the next.

3. Lee - 16 January 2009

I can see why people are confused.
Using te languages that sugest both abnormal and normal togeather is quiet confusing to some and admediately some will take this asa sign to hidhing something.

I am well aware of the danger in both areas a mass evacuation and ten having no eruption as perposed to doing nothing and ten there is an eruption at which from what I understnd all human life will be impacted in one way or another. In essence there is “No runing from this”

but back to wht I was speaking of earlier, when we say sometin is Unusal or abnormal were are talking aobut someting tat stands out from the rest in a peculiar way as to cause more scruntiny of the situation, then wehn we say the quakes are of “Normal” status for the volcano, this would enviatbly bring a great deal of confusion. I for on am not a scientist, how ever I am educated to know te differencce between abnormal and the normal..

Should the quakes be of an abnormal type then perhaps it is a possible that someting is aobut to occure.. espeicaly if theses quakes start shifting the hydro thermals around.

In my opionion u\you used abnormal and you have atracted quiet a bit of attention.Now we are left to ask our selves this question, What is realy going on?

Why are theses Both Normal and abnormal at the same time?
I was around when MT st Hellens erupted, I learend a valuable lesson that day, we heard reports it was going to erupt but many people passed it off as nothing tll the day it append, the only thing is MT st Hellens started the same way. and ground deformation was the last sign it gave befor it unleashe it s power.

I reaise you are profesionals, perhaps a public statement is in order on why it is normal and why it is abnormal.. there is a lot of data that one needs to gather and Yellow stone being the way it is built has no room for error one way or the other.
Perhaps a better anology is to say we are not for sure waht the events are that are taking place and we are studying it further..plain and easy to understand by the general public.


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