Yellowstone volcano: Why USGS scientists may fear earthquake swarms could spark eruption | Science | News

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The Yellowstone Caldera is a supervolcano located below Yellowstone National Park in the Western US. It sits between the states of Wyoming, Montana and Idaho and is constantly monitored by the United States Geological Survey (USGS) due to its capability to inflict disaster on a global scale if a supereruption occurs. The last event of this kind has not happened for more than 630,000 years and any serious eruption in 70,000 – which reportedly makes another supereruption overdue.

Earlier today, a magnitude 3.1 earthquake was recorded in Manhattan, Montana, just 100 miles from the Yellowstone caldera.

Though the tremors were small, they will still be of interest to scientists due to the high possibility of a swarm, which can see hundreds of small earthquakes in a short period of time.

USGS’s website explains: “Since 1973, there have been over 48,000 earthquakes located in the Yellowstone region. 

“Over 99% of those earthquakes are magnitude 2 or below and are not felt by anyone. 

Earthquake swarms raise fears of eruptions

Earthquake swarms raise fears of eruptions (Image: GETTY)

A 3.1 magnitude earthquake struck today

A 3.1 magnitude earthquake struck today (Image: GOOGLE)

Large swarms that can contain 1,000’s of earthquakes and last for months do occur on occasion

USGS

“Earthquake swarms (earthquakes that cluster in time and space) account for about 50 percent of the total seismicity in Yellowstone and can occur anywhere in the Yellowstone region, but they are most common in the east-west band of seismicity between Hebgen Lake and the Norris Geyser Basin.

“Most swarms are small, containing 10-20 earthquakes, and short, lasting for 1–2 days. 

“However, large swarms that can contain 1,000’s of earthquakes and last for months do occur on occasion.”

Earthquake swarms pose a threat as they can trigger a volcanic eruption, though scientists are unsure exactly how.

They believe the volcanic activity possibly occurs in response to a change in the local pressure surrounding the magma reservoir system as a consequence of severe ground shaking caused by the earthquake.

There was a brief period of anxiety among scientists in 2018, when “rapid-fire” swarms occurred.

This features earthquake swarms that seemingly appear out of nowhere that can churn out tens or hundreds of small to moderate quakes within a very short time frame.

On July 5, 2018, there was approximately 160 earthquakes of all sizes – with only 12 of them being felt.

However, the most “nervous” of times came 10 years earlier.

In December 2008, continuing into January 2009, more than 500 earthquakes were detected under the northwest end of Yellowstone Lake over a seven-day span, with the largest registering a magnitude of 3.9.

Yellowstone volcano poses a threat to the entire world

Yellowstone volcano poses a threat to the entire world (Image: GETTY)

Scientists have recorded earthquake swarms before

Scientists have recorded earthquake swarms before (Image: GETTY)

Jacob Lowenstein, who was tasked with monitoring the activity for the USGS, revealed during a lecture at Menlo Park, California, how his team were put on alert.

He explained how they spotted a linear trend of earthquakes heading towards the Yellowstone caldera.

He said in 2014: “Here are a couple of maps that show you what was happening during that period of time. 

“It turns out that the earthquakes were on a linear trend.

“It started with the blue, which are the early earthquakes, and then the red which are the latest. 

“They started at the south and they slowly moved north.

“This is another one of the cross sections.”

Though Mr Lowenstein was confident the earthquake activity would not be enough to spark a volcanic eruption, he did admit it was unsettling. 

He added: “This was a pretty nervous time for us, not because there was a lot of earthquakes, but because people were getting rather agitated about things happening beneath lakes.

“Lakes freak people out for some reason, because they can’t see what is happening.

“So people just hypothesised all sorts of crazy stuff and it was a very nervous time.

“There was a lot of earthquakes, but there was never any steam or anything more than small earthquakes.”



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