Yellowstone Quakes
Daily Earth Science Geosphere Repost

Yellowstone quakes and shakes, but will it blow?

Yellowstone saw 274 earth tremors in May of 2020. The largest of these tremors registered a magnitude of 3.1. But these tremors are not necessarily a sign that an eruption is imminent. 

When an area, like Yellowstone, experiences a large number of low magnitude earthquakes over a short period, they are collectively referred to as an ‘earthquake swarm.’ Such swarms are common in Yellowstone since it is one of the USA’s most seismically active areas. Any given year might see between 700 and 3000 small Yellowstone quakes in the park. However, in 1985 a swarm of 3,000 earthquakes occurred over three months.

The geology below Yellowstone Park includes an extensive network of faults and fractures, and the earthquake swarms relate to the movement of magma into these features. The general thinking is that these earthquake swarms are a good thing because they provide relief from the stresses building up in the rocks. A lot of small Yellowstone quakes help prevent a single big earthquake or eruption. 

Eruptions

The most famous of the Yellowstone eruptions occurred 640,000 years ago and created the caldera we see today. This eruption was 2,500 times larger than the May 18, 1980 eruption of Mt. St. Helens and left a crater that measures up to 43 miles across.

Magma pulsing upward through the earth’s crust caused the land to bulge upward at the planet’s surface. Then, when the overlying rock could no longer contain the pressure, cracks formed, opening up vents from the surface to the magma chamber. The pressure release was catastrophic, causing the uncontrolled ejection of gases, fluids, and magma up to 30 miles into the atmosphere. 

An eruption of that size today would affect temperatures globally and scatter ash across much of the USA. Pyroclastic flows would devastate areas near the volcano, turning the ground into a scorched glass surface. But the chances of such an event are considered low by most scientists. 

The most recent Yellowstone eruption was about 70,000 years ago and generated a lava flow but no catastrophic explosion. Also, scientists estimate that only about 15% of the upper rhyolite magma chamber is molten, raising the question of whether this super-volcano has enough energy for another mega-eruption. 

A trail of destruction

The pulse of magma causing the Yellowstone eruptions forms the Yellowstone hotspot. The term hotspot refers to the surface location of a plume of molten rock that rises hundreds of miles from the mantle to the earth’s surface. Hawaii and Iceland are also locations of hotspots.

Yellowstone National Park has not always been located over a hotspot. The mantle plume responsible for Yellowstone originates below the North American plate. So, the location of surface volcanoes shifts as the plate moves over the hotspot. For the Yellowstone hotspot, this process created a linear progression of surface volcanic eruptions that trace back to Eastern Oregon.

Along this trail of destruction, researchers found two super-eruptions, the McMullen Creek and Grey’s Landing eruptions at 8.99 million and 8.72 million years ago, respectively. The Grey’s Landing event turned an area the size of New Jersey into hot volcanic glass, vaporizing everything in its path. But the good news is that the frequency of these super-eruptions is decreasing with time. Perhaps the hot spot is finally playing out, and the current Yellowstone quakes and shakes are a swan song. We should have a final and definitive answer during the next half-million years, so don’t hold your breath.


ArcheanWeb:

The Icelandic Plume (Source: ArcheanWeb) – https://archeanweb.com/2020/03/25/the-icelandic-plume/ Also:

The Axial Seamount: a very active volcano (Source: ArcheanWeb) – https://archeanweb.com/2020/03/20/the-axial-seamount-a-very-active-volcano/ Also:

Yellowstone National Park, part of a living earth (Source: ArcheanWeb) – https://archeanweb.com/2020/03/26/yellowstone-national-park-part-of-a-living-earth/  Also:


Sources:

Earthquakes (Source: National Park Service) – https://www.nps.gov/yell/learn/nature/earthquakes.htm  Also:

Yellowstone volcano eruption: What would happen if Yellowstone erupted? (By LIAM DOYLE; Express) – https://www.express.co.uk/news/science/1291883/Yellowstone-volcano-eruption-what-would-happen-if-Yellowstone-erupted  Also:

Yellowstone Had Nearly 300 Earthquakes In May—But It’s No Biggie (By Suzanne Rowan Kelleher; Forbes) – https://www.forbes.com/sites/suzannerowankelleher/2020/06/05/yellowstone-had-nearly-300-earthquakes-in-may-but-no-biggie/#23c5f7fc2214 Also:

Questions About Yellowstone Volcanic History (Source: USGS) – https://www.usgs.gov/volcanoes/yellowstone/questions-about-yellowstone-volcanic-history  Also:

Yellowstone Discovery Suggests The Risk of Super-Eruption Is Actually Decreasing (By DAVID NIELD; Science Alert) – https://www.sciencealert.com/eruptions-in-yellowstone-s-past-suggest-its-most-violent-days-might-be-behind-it  Also:

Feature Image: Opal Pool (Modified) – By Opal_Pool_YNP2.jpg: Acroterionderivative work: Gaendalf – Opal_Pool_YNP2.jpg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12927108

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.

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