Yellowstone Caldera Resources

With the increased seismic activity in the Yellowstone Caldera, it is likely that there is some increased interest in in the geology of the area. Here are some resources that should be of interest.

First, we have a fairly recent peer reviewed publication on the "Super Volcano" known as Yellowstone, including some discussion of just what a "Super Volcano" is.

The largest scale of volcanic eruptions, the so-called super-eruptions, can destroy all living beings and infrastructure over tens of thousands of square kilometres, can disrupt agriculture over millions of square kilometres and can alter global climate for years or decades. As such, society must endeavour to create reliable volcano-monitoring systems that can detect the sorts of Earth processes leading to large-scale explosive volcanism. Although the volcanological community has had some success in predicting small eruptions, the scarcity of great eruptions over the past 150 years means that we have little experience understanding the prelude to major events. This is particularly true at caldera systems, which are capable of large-scale volcanism and exhibit frequent unrest but have undergone only small eruptions historically... The paper has some excellent graphics and the discussion of the geology is quite accessible.

Figure 2. Diagram illustrating seismic-wave-velocity anomalies in the shallow crust beneath Yellowstone as viewed from the southwest (adapted from Husen et al. 2004a). The orange volume outlines the anomaly attributed to partially molten rock extending above the main magma chamber (and beneath the surface expressions of the Sour Creek and Mallard Lake resurgent domes). The red volume is an anomaly with properties suggesting gas-filled fractured rock. The green dots are hypocentres from the 1985 earthquake swarm. The arrows are postulated trends of hydrothermal fluid flow from the magma body to the inferred gas-filled body ...

But wait! Before you download that, you may be more interested in a more recent and more written for the general public piece by Lowenstern and Hurwitz, available here. It's got even better graphics and is even more accessible.

Schematic cross-section of the crust beneath the Yellowstone Caldera based on Hildreth (1981) and Husen et al.

And when you are done reading these papers, you'll be the most well informed non-geologist visiting the USGS Yellowstone Volcano Observatory web site, located here.

And, as I've mentioned before, you can check out my earlier post on the caldera and my sister, Caldera Girl's, newspaper article on the subject.

Lowenstern, J.B., Hurwitz, S. (2008). Monitoring a Supervolcano in Repose: Heat and Volatile Flux at the Yellowstone Caldera Elements, 4, 35-40

Jacob B. Lowenstern, Robert B. Smith, David P. Hill (2006). Monitoring super-volcanoes: geophysical and geochemical signals at Yellowstone and other large caldera systems Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364 (1845), 2055-2072 DOI: 10.1098/rsta.2006.1813

Here’s some useful links.

I’ve seen a purported e-mail questioning a geologst connect with the Yellowstone Volcano Observatory, where the geologist questioned the analysis of the seismograph traces that appear to show harmonic tremors usually associated with magma movement.

The geologist suggested the higher than normal background vibrations might be a result of high winds in the area. Seismographs are typically isolated from surface vibrations, both mechanically and acoustically, however, if wind movement over a large area induced resonance in the ground strata, I suppose it’s possible for the instruments to pick it up in spite of careful isolation. The geologist said the area had been experiencing winds up to 70 mph at some of the times the rest state wave amplitudes indicated by the instruments was higher than “normal”.

In ay event, the question of whether there are harmonic tremors and magma movement is an important one.

Here is a link to the real time weather data for West yellowstone:

http://www.wunderground.com/cgi-bin/findweather/hdfForecast?query=est+Yellowstone&searchType=WEATHER

Here is a link to the LKWY seismograph trace:

http://www.quake.utah.edu/helicorder/lkwy_webi.htm

As you can see, in between minor tremors, the trace has been quiet since midnight, but between 1100 and noon local time, the background noise begins to grow in amplitude.

The increase in amplitude continues with the trace beginning at 1300, which is the last update currently available.

At 2:19PM local and at 2:23PM local the wind speed at the West yellowstone location shows 6mph and 7 mph respectively.

Since the seismograph data remains posted for five days, all we need are spot checks of the windspeed noted nearby for comparison, so if anyone checks that windspeed, it would be useful to post the time and windspeed indication in this thread.

If anyone can find and post links to hourly wind data at West Yellowstone going back to December 27th, that would be very useful too.

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