(Originally posted August 8, 2014)
Yellowstone National Park and the Yellowstone Volcano Observatory posted a brief article online recently titled "A Short Statement Regarding Recent Rumors" to help dispel rumors that have begun circulating -- again -- about a possible eruption of the Yellowstone super-volcano, reports of mass evacuations, and other such issues.
The YVO staff wrote:We have received enough concerned emails and phone calls that we've spent some time tracking down a few of the statements made on various "alternative Internet news sources."
Virtually everything known about Yellowstone's spectacular volcanic past comes from the scientists who work at this observatory, at all our eight member agencies.
We're the ones who mapped the deposits, figured out the ages of the eruptions, measured the gases, located the earthquakes, and tracked the ground movement. A few of us have been doing it for over forty years.
We will continue to help you understand what's happening at Yellowstone now, and what's likely to happen in the future.
UPDATE: In May 2015, the Yellowstone Volcano Observatory also addressed some of the misconceptions and rumors:
- Misconception #1: When Yellowstone erupts…. it'll be Armageddon.
The most likely explosive event to occur at Yellowstone is actually a hydrothermal eruption—a rock-hurling geyser eruption—or a lava flow. Though the worst-case scenario for a giant Yellowstone eruption is indeed bad, and could have global implications, most past eruptions at Yellowstone were not highly explosive.
As for the worst-case scenario, even previous Yellowstone supereruptions did not cause extinctions, and ash fallout on the other side of the continent was minimal.
- Misconception #2: The Yellowstone magma chamber is growing.
There's no evidence for that one. Though we get better and better at understanding the extent of magma beneath Yellowstone, that doesn't mean the magma storage region is growing. A study, done by scientists at the University of Utah (and colleagues at Caltech and the University of New Mexico), reveals a lot of partly molten rock, but nearly all of it appears too "frozen" to erupt.
Eruptions at Yellowstone are possible, but we have no evidence that enough melt has accumulated in one place to feed a supereruption (1000 cubic kilometers of volcanic debris). Again, if it were to erupt, the most likely type of eruption would be a comparatively non-explosive lava flow.
- Misconception #3: Yellowstone is overdue for a supereruption.
See #1. If it does erupt, it need not be a large eruption. Moreover, there's no necessity that there will be another supereruption. Most volcanic systems do not have multiple such events. When they do, the supereruptions are not evenly spaced in time. Finally, it is not valid to calculate a recurrence period solely on two values (the two intervals between supereruptions). Therefore, the calculations you may hear stating that Yellowstone is some number of years overdue for a supereruption is mathematically inaccurate.
- Misconception #4: Yellowstone is rapidly rising.
Not as of May 2015. Since regular monitoring of Yellowstone began in the 1970s, we have observed episodes of relatively rapid uplift and subsidence (3 to 5 inches per year), notably from 2004 to 2010. However, as of May 2015, not much is happening. Anyone interested can readily find the latest monitoring data or the Yellowstone monthly updates.
- Misconception #5: Earthquake data indicates moving magma.
Almost all earthquakes at Yellowstone are brittle-failure events caused when rocks break due to crustal stresses. Though we've been looking for years at Yellowstone, no one has yet identified "long-period (LP) events" commonly attributed to magma movement. When they are observed, that will not mean Yellowstone is getting ready to erupt. LP earthquakes are observed commonly at other volcanoes in the world, including California, which have not erupted for centuries or millennia.