Yellowstone's Volcano Bigger Than Thought

Yellowstone's Volcano Bigger Than Thought

SALT LAKE CITY — Yellowstone's underground volcanic plumbing is bigger and better connected than scientists thought, researchers reported here today (April 17) at the Seismological Society of America's annual meeting.

"We are getting a much better understanding of the volcanic system of Yellowstone," said Jamie Farrell, a seismology graduate student at the University of Utah. "The magma reservoir is at least 50 percent larger than previously imaged."

Knowing the volume of molten magma beneath Yellowstone is important for estimating the size of future eruptions, Farrell told OurAmazingPlanet.

Supervolcano trail

Geologists believe Yellowstone sits over a hotspot, a plume of superheated rock rising from Earth's mantle. As North America slowly drifted over the hotspot, the Yellowstone plume punched through the continent's crust, leaving a bread-crumb-like trail of calderas created by massive volcanic eruptions along Idaho's Snake River Plain, leading straight to Yellowstone. The last caldera eruption was 640,000 years ago. Smaller eruptions occurred in between and after the big blasts, most recently about 70,000 years ago. [Infographic: Geology of Yellowstone]

The magma chamber seen in the new study fed these smaller eruptions and is the source of the park's amazing hydrothermal springs and geysers. It also creates the surface uplift seen in the park, said Bob Smith, a seismologist at the University of Utah and author of a related study presented at the meeting.

"This crustal magma body is a little dimple that creates the uplift," Smith said. "It's like putting your finger under a rubber membrane and pushing it up and the sides expand."

Clearer picture

A clearer picture of Yellowstone's shallow magma chamber emerged from earthquakes, whose waves change speed when they travel through molten or solid rock. Farrell analyzed nearby earthquakes to build a picture of the magma chamber.

The underground magma resembles a mutant banana, with a knobby, bulbous end poking up toward the northeast corner of Yellowstone National Park, and the rest of the tubular fruit angling shallowly southwest. It's a single connected chamber, about 37 miles (60 kilometers) long, 18 miles (30 km) wide, and 3 to 7 miles (5 to 12 km) deep.

Previously, researchers had thought the magma beneath Yellowstone was in separate blobs, not a continuous pocket.

The shallowest magma, in the northeast, also matches up with the park's most intense hydrothermal activity, Farrell said. The new study is the best view yet of this zone, which lies outside the youngest caldera rim.

Additional molten rock, not imaged in this study, also exists deeper beneath Yellowstone, scientists think.

Comforting

Pun wrote:Comforting

Might give us a temporary respite from global warming. You know, that and destroy large swaths of farm land across the mid west...

Bryant wrote:

Pun wrote:Comforting

Might give us a temporary respite from global warming. You know, that and destroy large swaths of farm land across the mid west...

What would be the affected areas when eruption occurs??? I would guess this thing would put enough ash into the atmosphere to cover the globe for a few months, but I'm more interested in the areas of total devastation.

Marconius wrote:

Bryant wrote:

Pun wrote:Comforting

Might give us a temporary respite from global warming. You know, that and destroy large swaths of farm land across the mid west...

What would be the affected areas when eruption occurs??? I would guess this thing would put enough ash into the atmosphere to cover the globe for a few months, but I'm more interested in the areas of total devastation.

Here is a map of ash fall deposits from previous eruptions. Also note the St. Helens and Long Valley Caldera (second largest volcano in N. America loc. in E. California) ash deposits are mapped for reference.



Eruptions of the Yellowstone volcanic system have included the two largest volcanic eruptions in North America in the past few million years; the third largest was at Long Valley in California and produced the Bishop ash bed. The biggest of the Yellowstone eruptions occurred 2.1 million years ago, depositing the Huckleberry Ridge ash bed. These eruptions left behind huge volcanic depressions called “calderas” and spread volcanic ash over large parts of North America (see map). If another large caldera-forming eruption were to occur at Yellowstone, its effects would be worldwide. Thick ash deposits would bury vast areas of the United States, and injection of huge volumes of volcanic gases into the atmosphere could drastically affect global climate. Fortunately, the Yellowstone volcanic system shows no signs that it is headed toward such an eruption in the near future. In fact, the probability of any such event occurring at Yellowstone within the next few thousand years is exceedingly low. -USGS

A good source of info: USGS Volcanic Hazards Program

The size of the affected area will depend greatly on the type of eruption. If it is a basaltic lava with low volatiles the affects will be incredibly local (picture Hawaii type eruption). If the eruption is a caldera forming event (ie so much is erupted that the surface of the earth collapses on the depleted magma chamber), expect something along the lines of the Huckleberry Ridge or Lava Creek ash fall areas. Smaller, non-caldera forming rhyolitic eruptions could result in a considerably smaller ash fall area than the caldera forming events, but still effect areas in the mid west.

Also note: The mapped ash bed areas are only the areas where enough ash was present to form a locatable/datable bed. Finer ash was probably deposited (but not preserved in clear beds) over a much larger area.

Oh yeah it wouldnt be pretty anywhere in the lower 48

What is out prediction capabilities for this thing???

I'm guessing these things give years of notice.

Marconius wrote:What is out prediction capabilities for this thing???

I'm guessing these things give years of notice.

Well, scientists haven't exactly been all that great at predicting volcanoes to date, but I guess something this big will give enough warning that you'll have time to pack a bag and head to, well, I dunno, brazil?

Yeah, no joke, what are gonna evacuate the whole interior of the country? Plus all that ash would fall on the bread belt, a d worldwide famine would take place. The climate would definitely change globally, and ppl would have a hard go it for many years to follow

I watched dantes peak lol

Pun wrote:I watched dantes peak lol

I'm sorry, I didn't know...

:-P

Least it was better than Tommy Lee Jones in "Volcano" I guess....

Pun wrote:I watched dantes peak lol

Quit shit talking Dante's Peak, it had James Bond as a volcanologist! That movie is actually the reason I initially got interested in volcanology, I saw it on VHS when it first came out and one of my parents made the mistake of telling me that there was an active volcano only ~30-40 miles from our house. I quickly jumped on the internet (well, 56K, so perhaps quickly wouldn't be the word to use) and went to check out the USGS Long Valley Observatory volcanic hazards page. It predicted up to 4 feet of ash where I lived. I was about eight and probably wasn't much more than 4 feet tall. It both scared and fascinated me.

x2 on what Miles said. While Dante's Peak tried to get it right (there are several serious flaws, but they actually consulted several geologists), Volcano threw all reality to the wind. The only thing worse than the acting in that movie is its interpretation of science (my favorite part was when they stopped a >5000ºC basalt flow with the sheet metal of the city bus, in reality that would have melted instantly).

Not melted, but would burn prior to the lava hitting it.

Still some pretty cool effects for its day. The one with tommy lee jones abt the volcano under LA had to be worse though

Marconius wrote:What is out prediction capabilities for this thing???

I'm guessing these things give years of notice.

Unlike with earthquakes, our prediction abilities with volcanoes is reasonably good. There are several key things we like to keep an eye on. When magma forces its way through the earth it wedges the bedrock apart, which results in large numbers of small earthquakes. We can detect these earthquakes with seismometers and map out where the magma is moving. We can also look at the deformation of the earths crust from magma movement (take for instance the bulge on the side of St. Helens that appeared well before the eruption). We can also look at hydrothermal systems and gas emissions. The main challenge is to not jump the gun and unnecessarily put the public into a panic. In the 1980s it looked like there was a good chance that there would be an eruption from Long Valley Caldera. We had rapid growth of the resurgent dome, lots of shallow seismic swarms suggesting magma was moving fairly shallow in the crust, CO degassing that killed of acres of trees on the flank of Mammoth Mountain (just outside of the city of Mammoth Lakes), and changes in the hydrothermal system. The USGS changes its monitoring system, which was misinterpreted by the press to mean an eruption of imminent. People panicked and the USGS was falsely blamed. Ultimately, volcanic activity tapered off and no eruption occurred (although in recent years some of the hot spring temperatures have gone up dramatically, resulting in the Inyo National Forest closing some cool swimming holes).