Pulse Reveals Beating Heart Of A Supervolcano (Yellowstone)

New Scientist ^ | 2-1-2006 | Jessica Marshall

[blam]

Pulse reveals beating heart of a supervolcano

01 March 2006
From New Scientist Print Edition
Jessica Marshall

"I DON'T think visitors appreciate that they're standing directly on top of the largest, most dynamic magmatic system on the planet," says geologist Daniel Dzurisin. While the supervolcano that is Yellowstone National Park won't be erupting any time soon, he and his colleagues have uncovered a surprising source of volcanic activity beneath tourists' feet, which was probably the reason trails had to be closed in 2003.

The Yellowstone caldera formed 640,000 years ago in an explosion of magma more than 1000 times greater than the Mount St Helens eruption in 1980.
While it is common knowledge that the caldera floor rises and falls, the source of the motion remains uncertain. According to a previous popular theory, the accumulation and release of fluid not far beneath the surface is driving the cycles, but Dzurisin, of the David A. Johnston Cascades Volcano Observatory in Vancouver, Washington, and his colleagues say a deeper source best explains their latest findings.

The team, led by Charles Wicks of the US Geological Survey in Menlo Park, California, used a series of satellite measurements to determine the fluctuations in elevation - up to 120 millimetres - over a seven-year period.

Although the floor of the caldera began subsiding in 1997, the researchers uncovered a new region of activity beneath the north rim of the caldera that continued to swell from 1995 until 2002.
Models incorporating the measurements indicate that the source of the upward push was 10 to 16 kilometres beneath the surface in the basaltic magma layer, well below the level of the fluid suggested as the source of the motion (Nature, vol 440, p 72).

The picture is one of magma flow driving the undulation of the surface, flowing upward from beneath the caldera floor towards the northern rim and then down and out from beneath the rim.
Seismic activity near the exit acts as a valve, suggests Wicks, blocking or releasing the magma outflow. This explains why the rim and floor can swell and sink at different times.

The idea also explains the rise in thermal activity in the rim area in 2003, Wicks says, when some trails had to be closed because of increased steam releases and a rise in surface temperatures.
The swelling magma could have cracked the crust, creating new avenues for steam to escape to the surface, he says.

From issue 2541 of New Scientist magazine, 01 March 2006, page 11

[xcamel]

see: http://www.freerepublic.com/focus/f-news/1588061/posts

[Ikemeister]

it's the Bush Administration's fault.

[golfisnr1]

If that thing blows you can say bye-bye to global warming.
It would block out the sun and we would be back in an ice age before you could convince an enviromentalist that there was a problem.

[RightWhale]

Was it a volcano that doomed Rome? Can't remember right now. One thing that might relate is that a lot of Roman gold went to India, large trade, and when Rome collapsed, so did India. The Southeast Asia civilizations of Indonesia, Cambodia, etc. were offshoots of the Indian civilization at its prime and when India collapsed, so did the eastern partners. Looks like the Roman collapse resonated all the way to Vietnam. A thousand years of Dark Ages all through that and sealed with the moslem military campaigns.

[thoughtomator]

That's Pompeii you're thinking of... south of Rome and a lot earlier.

[raybbr]

And this thread, too.

[RightWhale]

I have been to Vesuvius and peered into the smoking caldera. That wasn't the one.

[xcamel]

Their estimate of the power of an explosive eruption was a bit short too. it's 100,000 times St Helens just in shear ejection mass. (Think Toba, Tamboura, and Krakatoa)

[COEXERJ145]

Think Toba, Tamboura, and Krakatoa

Toba was a supervolcano while Tambora and Krakatau were not. Tambora and Krakatau just happened to be very large eruptions but no where close to Toba or Yellowstone.

[blam]

Over here. It's always something. LOL

[RightWhale]

George Noory could not pronounce Krakatoa last night. Kind of funny for a professional news reader.

[Dan(9698)]

I think it was 640,000 years ago it last erupted.

In Idaho, you can see three layers of lava flow, the oldest looks very weathered, the middle one looks partially weathered, the most recent one looks very fresh.

I heard it erupts every 600,000 years, so it is now overdue.

We live in Riverton WY about 150 miles South East of it.

[blam]

"Toba was a supervolcano while Tambora and Krakatau were not. Tambora and Krakatau just happened to be very large eruptions but no where close to Toba or Yellowstone."

Yup. Toba was the bad boy 74,000 years ago. The human population of the world was decreased to 2,000 with some estimates ranging to only 10,000 survivors worldwide.

The 'Hobbits' on Flores Island survived it.

[xcamel]

World's Largest Calderas

The Biggest of the "supervolcanoes"

Caldera name	Country	Location	Size (km)	Most recent eruption*
La Pacana	Chile	23.10 S 67.25 W	60 x 35	Pliocene
Pastos Grandes	Bolivia	21.45 S 67.51 W	50 x 40	8.3 Ma
Kari Kari	Bolivia	19.43 S 65.38 W	30	Unknown
Cerro Galan	Argentina	25.57 S 65.57 W	32	2.5 Ma
Awasa	Ethiopia	7.18 N 38.48 E	40 x 30	Unknown
Toba	Indonesia	2.60 N 98.80 E	100 x 35	74 ka
Tondano	Indonesia	1.25 N 124.85 E	30 x 20	Quaternary
Maroa/ Whakamaru	New Zealand	38.55 S 176.05 E	40 x 30	500 ka
Taupo	New Zealand	38.78 S 176.12 E	35	1,800 yr
Yellowstone1	USA-WY	44.58 N 110.53 W	85 x 45	630 ka
La Garita	USA-CO	37.85 N 106.93 W	75 x 35	27.8 Ma
Emory	USA-NM	32.8 N 107.7 W	55 x 25	33 Ma
Bursum	USA-NM	33.3 N 108.5 W	40 x 30	28-29 Ma
Longridge (McDermitt)1	USA-OR	42.0 N 117.7 W	33	~16 Ma
Socorro	USA-NM	33.96 N 107.10 W	35 x 25	33 Ma
Timber Mountain	USA-NV	37 N 116.5 W	30 x 25	11.6 Ma
Chinati Mountains	USA-TX	29.9 N 104.5 W	30 x 20	32-33 Ma
Long Valley	USA-CA	37.70 N 118.87 W	32 x 17	50 ka
greater Maly Semiachik/Pirog2	Russia	54.11 N 159.65 E	50	~50 ka
greater Bolshoi Semiachik2	Russia	54.5 N 160.00 E	48 x 40	~50 ka
greater Ichinsky2	Russia	55.7 N 157.75 E	44 x 40	~50 ka
greater Pauzhetka2	Russia	51 N 157 E	~40	300 ka
greater Ksudach2	Russia	51.8 N 157.54 E	~35	~50 ka

_{* Ma is million years ago, ka is thousand years ago, Pliocene is 5.3-1.8 Ma, Quaternary is 1.8-0 Ma.
¹Yellowstone and Longridge are the ends of a chain of several large calderas extending beneath the Snake River Plain, each comparable in size.
²The Russian calderas are informally named here for the smaller modern calderas and active volcanoes that lie within them.}

Source: Cambridge Volcanology Group caldera database

[raybbr]

Toba caldera.

[battlegearboat]

Don't feed the bears.

[Max in Utah]

When, not if, Yellowstone blows up again you can pretty much kiss the middle of the US goodbye.

[Strategerist]

I heard it erupts every 600,000 years, so it is now overdue.

It's absolutely absurd to proclaim Yellowstone "overdue" because the eruption interval dataset consists of only three eruptions and two intervals. And it's not even overdue by that metric.

[gieriscm]

ping

[Dan(9698)]

It's absolutely absurd to proclaim Yellowstone "overdue"

Just repeating what I heard on a program on Discovery.

They probably hyped it and simplified it for us masses.

I know that the north end of the lake is bulging up because it is spilling water out the south end and the constant water is killing a bunch of trees there.