Yellowstone Supervolcano waking up?

A swarm of over 1100 earthquakes recorded in the Yellowstone caldera over the past month prompted scientists to quell concerns about a dormant Yellowstone 'Supervolcano' slowly waking up.

Experts at the US Geological Survey say the risk of the Yellowstone Supervolcano erupting is quite low (the probability is calculated at one in 730,000). There have been three major 'caldera-forming eruptions' in Yellowstone in the last 2.1 million years, the last occurring 640,000 years ago. Since then, there have been a number of smaller erurptions, with the last one emitting rhyolite lava, causing the Pitchstone Plateau flow some 70,000 years ago, the UUSS wrote.

However, concerns escalated on July 6, 2017 after a strong Magnitude 5.8 earthquake hit western Montana - the strongest quake to hit the area in the past 20 years - the U.S. Geological Survey reported.

Mike Stickney, seismologist, found the location 'not surprising'. 'It’s right along the axis of the intermountain seismic belt.'. He said the quake occurred on a strike/slip fault, a vertical fault where one side moves horizontally against the other, similar to the kind of movement experienced along the San Andreas Fault in California.

That said, he said he 'does not believe' the quake is seismically tied to the recent 'swarm' of smaller earthquakes in the Yellowstone National Park.

But even if the Yellowstone Supervolcano would erupt, 'it's most likely to be a lava flow, as occurred in nearly all the 80 eruptions since the last 'supereruption' 640,000 years ago,' said Jacob Lowenstern from Yellowstone Volcano Observatory (YVO). 'A lava flow would be a big deal at Yellowstone, but would have very little regional or continental effect.'

Still, his own research paints a different picture: The last full-scale eruption of the Yellowstone Supervolcano, the Lava Creek eruption which happened approximately 640,000 years ago, ejected approximately 1,000 cubic kilometers of rock, dust and volcanic ash into the sky[1]. Ash spread over many tens of thousands of square kilometers[2].

Scientists believe that three super-eruptions have occurred in the past on a 600,000-700,000 year cycle, starting around 2.1 million years ago. The last huge eruption is thought to have occurred around 640,000 years ago. Do the math yourself.

Sleep well Americans. Nothing to worry about.

[1] Lowenstern et al: Steam Explosions, Earthquakes, and Volcanic Eruptions—What’s in Yellowstone’s Future? in U.S. Geological Survey: Fact Sheet – 2005
[2] Mastin et al: Modeling ash fall distribution from a Yellowstone supereruption in G3 - Geochemistry, Geophysics, Geosystems - 2014