Unmellow Yellow

Does recent unusual geothermic and seismic activity in Yellowstone Park foretell a coming cataclysmic event in the area?

Claim:   Recent unusual geothermic and seismic activity in Yellowstone Park foretells a coming cataclysmic event in the area.

Status:   Undetermined.

Example:   [Collected on the Internet, 2003]

A co-worker was talking about Yellowstone National Park. He said certain areas of the park were closed due to the high temperature of the ground. (About 200 degrees F.) He also said that sulfuric acid fumes were being emitted from the same "Hot Spot's". In the same general area, in some spots in the park, the surrounding area has lifted some 30 inches over the last 5 years, indicating that some sort of geothermal pressure is building in the area. As I type this out, it seems ridiculous to me but there's more. This is supposed to be building to some cataclysmic event, similar to a monstrous volcanic eruption.

Origins:   The spectacular natural beauty that is Yellowstone Park is the result of a massive volcanic eruption which took place 600,000 years ago. That cataclysmic event spewed enormous amounts of ash — enough to cover all of the western U.S., much of the midwestern U.S., northern Mexico, and some areas of the eastern Pacific — and blew up miles of mountain range. It left Volcano a caldera (a large crater formed by volcanic explosion or by the collapse of a volcanic cone) 28 miles wide by 46 miles long.

Yellowstone sits atop an underground volcano. To this day, geothermal activity continues in the area, the presence of the park's geysers bearing witness to this ongoing state of affairs. The park has weathered 29 sizeable eruptions of its volcano in the last 630,000 years (which works out to an average of one every 20,000 years), yet the last was 70,000 years ago. But even if there were never to be another volcanic spewing, the morass of partly molten material 5 to 10 miles below the park exerts powerful influence on the landforms above it. What park visitors perceive as solid ground is always moving up and down on its lake of magma, the movement averaging one and a half centimeters per year.

The park is constantly in a state of flux, so changes to the state of its features is to be viewed as the ordinary course of things. ("Change is what we expect in Yellowstone," said the park geologist, Hank Heasler.) Yet the perceived radical nature of the geological events of the summer of 2003 leave some worried that a sizeable volcanic event is in the offing.

Norris is the hottest and most seismically active geyser basin in Yellowstone. In the space of a few days in July 2003, acidic ground water dissolved parts of the unpaved trails through it, and the ground temperature in that area shot up to 200°F from its usual maximum of 80°F.

Each year the area experiences a noticeable change in the color and steam discharge of many of its existing geysers and thermal pools, an event known as "the annual disturbance." The annual disturbance in 2003 was larger than usual and lasted longer than
the norm. It resulted in the formation of a number of new steam vents and mud pots and significantly increased measured ground temperatures. Porkchop Geyser, which had been dormant since 1989, sprang back to life on 16 July 2003. Consequently, trails in the most disturbed areas were temporarily closed until conditions improved. By October 2003, three of the four temperature monitoring sites in the affected area indicated ground surface temperatures of less than 120°F, so most of the trails were re-opened — approximately 4,800 of the 5,800 feet shut in mid-summer. (In total, there are about 12,500 feet of trails in the Norris Geyser Basin, which means that even during the worst of the summer's events more than half of the trails through this active region remained open.)

On 21 August 2003, a magnitude 4.4 earthquake occurred under the southern boundary of the park. Earthquakes are commonplace in Yellowstone (it's one of the most seismically active places on the planet, enduring hundreds of shakings a year), but by far the greatest part of the tremors weathered are of the almost unnoticeable variety. Quakes of a magnitude of 4 or higher are relatively rare, usually taking place only every other year. Within the last few years, seismic activity in the park has decreased mightily, down from a half-dozen to twenty quakes to only one or two a day which causes some to be fearful because according to one widely accepted theory, a multiplicity of small quakes serves to release pressure building along fault lines (where one tectonic plate pushes up against another). If this pressure is not let off in small amounts, so the theory goes, it will intensify until it is all released in one massive quake. The U.S Geological Survey labels this belief a myth:
Seismologists have observed that for every magnitude 6 earthquake there are 10 of magnitude 5, 100 of magnitude 4, 1,000 of magnitude 3, and so forth as the events get smaller and smaller. This sounds like a lot of small earthquakes, but there are never enough small ones to eliminate the occasional large event. It would take 32 magnitude 5's, 1000 magnitude 4's, 32,000 magnitude 3's to equal the energy of one magnitude 6 event. So, even though we always record many more small events than large ones, there are never enough to eliminate the need for the occasional large earthquake.
In 1959 a deadly quake (7.5 on the old Richter scale) hit near the park. It dislodged a huge slice of a mountain west of the park, buried 25 campers as they slept in a national forest campground and dammed the Madison River to create Quake Lake.

New measuring techniques have revealed the presence of a bulge under Yellowstone Lake that rises 100 feet from the lake floor and stretches 700 feet. Some speculate pressure under this dome is building and worry an explosion of it could carve an underwater crater stretching up to 2,300 feet across. Others wonder if this "inflated plain" hasn't existed for a very long time and is thus quite stable. Its presence was revealed by a new mapping technique involving the use of sound waves to produce a bathymetric map of the body of water.

Although experts at the U.S. Geological Survey concede the 2003 happenings in the Norris Geyser Basin have been a bit unusual, they do not appear to believe they are volcanic in origin:
There is no evidence that magma beneath the enormous Yellowstone caldera is directly involved in the recent changes at Norris or Nymph Lake. Though magma as shallow as 3-6 miles beneath Norris does provide the heat for the geothermal system, the current activity is very unlikely to reflect magma ascent or increased likelihood of volcanism at Yellowstone Park. If magma were to rise to shallow levels beneath the ground it would be accompanied by intense swarms of local earthquakes and extensive displacement (deformation) of the ground surface around Norris. Thus far, caldera-wide seismicity and ground deformation have remained at typical background levels beneath Yellowstone and Norris.
Whether recent events and findings at Yellowstone represent nothing more than a slightly unusual blip in the park's geothermal and seismic history or whether they herald a coming disaster can't be definitively stated. Although there is no indication any of the changes suggest an impending eruption, park officials are writing a hazard plan in case the region grows more active.

Barbara "in suspected terrain" Mikkelson

Additional information:
    Yellowstone Park   Yellowstone Park
  (National Park Service)
    Yellowstone Lake FAQ   FAQ: Recent Findings at Yellowstone Lake
  (U.S Geological Survey)

Last updated:   21 July 2007

  Sources Sources:
    Erickson, Jim.   "Danger Lurks in Yellowstone Lake."
    Rocky Mountain News.   25 October 2002   (p. A32).

    Henderson, Diedtra.   "Lake's Bulge Could Warn of Massive Blast."
    The Denver Post.   10 August 2003   (p. A1).

    Robbins, Jim.   "In Yellowstone, A Subterranean Volcano Exerts Its Influence."
    The New York Times.   7 October 2003   (p. F2).

    Yellowstone National Park News Release.   "Portions of Norris Geyser Basin to Re-Open to Public."
    8 October 2003.

    Yellowstone National Park News Release.   "Increased Thermal Activity at Norris Geyser Basin Requires Temporary Closure."
    22 July 2003.

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