Tuesday, June 27, 2017

Scientists Confirm Yellowstone Supervolcano Was Hit By 450 Earthquakes In One Week

Yellowstone supervolcano was recently hit with over 450 earthquakes, prompting scientists to closely monitor the area. The first of the swarm of earthquakes began on June 12 and continued in the following days, including up to a 4.5 magnitude earthquake.
It's important to note that despite Yellowstone supervolcano's ability to erupt catastrophically, there do not appear to be signs that this swarm of earthquakes is leading to an eruption.
Geologists have monitoring systems setup surrounding the Yellowstone supervolcano that can detect seismicity underground. This monitoring system both provides data for researchers to better understand the volcano and as an early warning system. In this case, the most recent swarm of earthquakes likely was a result of the magma within the supervolcano moving through channels and conduits as it continues to fill.
The recent 4.5 magnitude earthquake was the largest to hit Yellowstone since March of 2014 when a 4.8 magnitude earthquake struck the area. Most of the earthquakes were limited to magnitudes below 1 and within the upper 9 miles of the crust. Keep in mind the earthquake magnitude scale is logarithmic, so a magnitude 2 earthquake is 10 times more powerful than a magnitude 1 earthquake.
This isn't the first time earthquake swarms have hit Yellowstone, but the latest swarm was seven years ago in 2010. In fact, it's not uncommon that earthquakes tend to hit in swarms. As crustal rock breaks and produces an earthquake, strain is transferred to another location and often times causes a chain of crustal breaks.
 Location of the Yellowstone earthquakes that are part of the larger swarm.
Location of the Yellowstone earthquakes that are part of the larger swarm.
Scientists are acutely in tune with the daily happenings of the Yellowstone supervolcano given its history of global scale eruptions. This particular event was marked as a "green" by the USGS, providing clear direction that the geologists monitoring the supervolcano do not expect any imminent threat.
However, it's important to keep in mind the devastating power this supervolcano has displayed in the past. The volcano erupted 2.1 million years ago, 1.3 million years ago and 630,000 years ago. Given the semi-regularly spaced cadence in eruptions and decades of research, scientists can clearly say that Yellowstone will erupt again.
Unfortunately, it's nearly impossible to predict the date of eruption and therefore scientists are limited to using geologic history, analogues, and statistics. One thing is certain, the next big eruption of the Yellowstone supervolcano will have a devastating impact globally, potentially giving rise to a volcanic winter.
The USGS estimates the probability of a large eruption from Yellowstone is 1 in 730,000 over the coming year. The USGS published a report in 2014 on the estimated impact from a Yellowstone eruption. In that report, it is estimated that most of the continental United States would be covered in ash, with areas in the northern Rocky Mountains covered by several meters of ash.
Highlighted areas are where ash beds have been identified from previous Yellowstone supervolcano eruptions.
Highlighted areas are where ash beds have been identified from previous Yellowstone supervolcano eruptions.
The Yellowstone supervolcano is a result of a hotspot similar to the one that formed the Hawaiian Island chain. The Yellowstone hotspot is a result of mantle convection of magma that upwells through the lithosphere (Earth's crust) at Yellowstone. As an analogy, imagine a match held underneath the middle of a piece of cardboard. Eventually, the match would burn its way through the cardboard, similar to the hotspot burning its way through the lithosphere.

Trevor Nace is a geologist, Forbes contributor, and adventurer. Follow him on Twitter @trevornace

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