Posted on 11/10/2003 10:05:00 AM PST by John H K
Is there a bulge beneath the lake?
Mapping of the lake bottom has revealed a variety of faults, hot springs and craters beneath Yellowstone Lake. In a recent scientific report (Morgan et al., 2003), one feature was informally named the "inflated plain" by USGS researcher Lisa Morgan, who organized surveys of the lake beginning in 1999. In mapping the entire lake, she and her colleagues identified a region about 2,000 feet long that rises about 100 feet above the lake floor. The area is in the northern part of Yellowstone Lake, south-southwest of Storm Point. The area is home to many hot springs and the nearby sediments have undergone chemical changes (alteration) due to the flow of thermal water.
Why was it called the "inflated plain"?
Seismic images of the lake sediments in this area show that they were tilted, hinting that the region may have been pushed up or "inflated." The amount of inflation would be much less than the 100-foot height of the feature, but is currently unknown. The images appear to indicate that the uplift is associated with accumulation of gas from Yellowstone's hydrothermal (hot water) system. Similar inferred gas accumulations were also noted elsewhere within the lake. Future research will assess the amount of uplift and its origin, whether by gas buildup or other potential mechanisms.
Has the "inflated plain" been growing?
At present, there is no evidence of recent growth of any features beneath the lake, and there is no indication that residents or visitors are in any danger. Temperature measurements from hydrothermal vents taken this year indicate no change in temperatures compared to those taken last year. The feature may have been there for decades or much longer.
So what's the big deal?
There may be none. This region has active hydrothermal features, and possibly some uplift. It's possible that the area could host future hydrothermal explosions, but so could other areas beneath the lake and other areas within the Park.
What's a hydrothermal explosion?
Hydrothermal explosions occur when water that feeds Yellowstone's geysers and hot springs is explosively flashed to steam, breaking rocks and throwing them into the air. Small hydrothermal explosion events occur every few years at Yellowstone, mostly in the geyser basins, and usually pose little hazard. There is geologic evidence for a few large hydrothermal explosions, some leaving craters thousands of feet across near Yellowstone Lake and in other areas of the park. Such large explosions have not occurred within the last several thousand years. Two classic papers discuss evidence for hydrothermal explosions at Yellowstone, both in the geyser basins (Muffler et al., 1971) and beneath Mary Bay in Yellowstone Lake (Wold et al., 1977).
Do any of the features beneath the lake relate to possible volcanic eruptions?
It is very unlikely. All active features are related to faults and hot water (hydrothermal) vents. Identified craters were formed by collapse or as a result of old hydrothermal explosions. Many of the rocks beneath the lake are lava flows more than 100,000 years old.
Is there any possibility of a toxic gas emission from Lake Yellowstone as occurred in Africa some years ago?
No. What occurred in Cameroon (Lake Nyos in 1986) resulted from CO2 buildup in the bottom waters of a tropical lake. In warm climates, lakes easily become stratified. In cold climates, however, the waters of lakes "turn over" once or twice per year. Cold water from melting ice sinks to the bottom of the lake. This creates a well-mixed lake with minimal potential for gas buildup. In addition, the CO2 at Lake Nyos was cold and not associated with thermal water. Waters and gases from the hot vents beneath Lake Yellowstone will tend to rise through the lake due to their low density.
Is anybody assessing the hazards from new hydrothermal explosions?
A geologic hazard assessment of Yellowstone National Park is underway by YVO. The assessment will evaluate the known and potential hazards at Yellowstone from earthquakes, volcanic eruptions and hydrothermal explosions. Any new information on Yellowstone Lake will be made available to YNP officials and the general public.
--------------------------------------------------------------------------------
References: Morgan, L.A., Shanks, W.C. III, Lovalvo, D.A., Johnson, S.J., Stephenson, W.J., Pierce, K.L., Harlan, S.S., Finn, C.A., Lee, G., Webring, M., Schulze, B., Duhn, J., Sweeney, R., Balistrieri, L., 2003, Exploration and discovery in Yellowstone Lake: results from high-resolution sonar imaging, seismic reflection profiling and submersible studies: Journal of Volcanology and Geothermal Research, v. 122, p. 221-242.
Morgan, L.A., Shanks, W.C., Lovalvo, D., Lee, G., Webring, M., Stephenson, W.J., and Johnson, S.Y., 2003, The Floor of Yellowstone Lake is Anything but Quiet: New Discoveries from High-Resolution Sonar Imaging, Seismic Reflection Profiling and Submersible Studies, In Morgan, L.A., ed., Integrated Geoscience Studies in the Greater Yellowstone Area: Volcanic, Hydrothermal and Tectonic Processes in the Yellowstone Geoecosystem, U.S. Geological Survey Professional Paper (in press). Also available in: Yellowstone Science, v. 11, no. 2 (Spring 2003), pp. 14-30. Article in two parts (2nd part is here).
Muffler, L.J.P., White, D.E., and Trusdell, A.H., 1971, Hydrothermal explosion craters in Yellowstone National Park: Geological Society of America Bulletin, v. 82, p. 723-740.
Wold, R. J., R. B. Smith, and M. A. Mayhew, 1977, Geophysical study of a hydrothermal explosion crater in Mary Bay, Yellowstone Lake, Wyoming, J. Geophys. Res., 82, p. 3733-3738.
And of course there's on FReeper that, every time there's a really large quake elsewhere in the world, starts running around claiming it "triggered" activity at Yellowstone because he looks at an unfiltered Yellowstone seismograph plot that is simply showing the wave arrivals from thousands of miles away :-).
The key thing is people not understanding that there's a wide spectrum between "nothing" and "massive North-America destroying Caldera blast" with 99.99% of the activity towards the "nothing" scale. The bulge on the lake has nothing to do with a Caldera blast.
And there's been no increase in seismicity actually located at Yellowstone.
Quakes are like Orgasms. Those that can't be detected without scientific instruments don't count.
So9
How'd these idiots overlook the magma chamber below the park, the ongoing uplift/earthquake research, and the MASSIVE* past volcanic eruptions of the slumering Yellowstone supercaldera?
*Massive, massive, massive. Three times in the last 2 million years Yellowstone has blown up in a supervolcano with ash covering the land from Washington state to Missouri. The next one ain't gonna be any fun either.
LOL
Cats eat bear meat! Bozeman rules.
Let's talk in two weeks... I never met a cat I didn't like!
Well, crap! I guess I have to start counting on a stray asteroid or something. I think the "GREAT RESET BUTTON" is long overdue.
On what can I pin my hopes? ;-D
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.