science

Yellowstone volcano: How a magnitude 7 EARTHQUAKE rocked Yellowstone again after 60 years


was the site of a cataclysmic incident on August 17, 1959, known today as the Hebgen Lake earthquake. The Yellowstone earthquake, which peaked at magnitude 7.2, caused the national park to drop as much as 20ft (six metres) in places. The earthquake only lasted approximately 30 seconds but the powerful tremors caused waters as far as Hawaii to rise up in wells. And as a result of the disaster, which killed 28 people, a large landslide swept over Madison River and created Quake Lake in Montana, US.

Now, nearly 60 years after the devastated Yellowstone volcano, geologists are still recording aftershocks in the Yellowstone area.

According to the University of Utah, a swarm of more than 3,000 aftershocks struck Yellowstone between June 2017 and March 2018.

The earthquakes were recorded in the Maple Creek area in northwest Yellowstone and can “at least partially” be traced back to the 1959 earthquake.

The incredible discovery was published in a study in the journal Geophysical Research Letters.

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Keith Koper, director of the University of Utah Seismograph Stations, said: “These kinds of earthquakes in Yellowstone are very common.

“These swarms happen very frequently. This one was a little bit longer and had more events than normal.”

A portion of the 3,000 Maple Creek earthquake fell along the same fault line as the Hebgen Lake cataclysm.

Fault lines are fractures in the Earth’s surface and are typically hotbeds of seismic activity.

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According to the US National Park Service (NPS), there is an “enormous number of faults associated with the volcano”, which result in 1,000 to 2,000 Yellowstone earthquakes each year.

Thankfully, Dr Koper and study co-author Guanning Pang did not find any evidence of the earthquakes being triggered by magma moving beneath the ground.

Mr Pang, a PhD student and seismologist at Utah, said: “We don’t think it will increase the risk of an eruption.”

The two geologists argued it is not unusual for an earthquake as powerful as the one in Yellowstone to produce aftershocks for decades after the initial incident.

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In 2017, for example, Mr Pang studied the aftershocks of an earthquake which erupted at Borah Peak in central Idaho, US, in 1983.

Dr Koper said: “There are formulas to predict how many aftershocks you should see.

“For Hebgen Lake, there looked like a deficit in the number of aftershocks.

“Now that we’ve had these, it has evened things out back up to the original expectations.”



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