The Yellowstone volcano sits in between the US states of Wyoming, Montana and Idaho, inside the Yellowstone National Park. The caldera is labelled a supervolcano due to its capability to inflict disaster on a global scale should another supereruption occur. The last event of this kind has not occurred for more than 630,000 years and any serious eruption in 70,000 – which apparently makes it overdue.
However, United States Geological Survey (USGS) scientists were put on high alert in 2002 when the Denali earthquake occurred in Alaska.
This 7.9 magnitude event was the largest recorded in the US in 37 years, a scientist revealed.
Jacob Lowenstein, who is in charge of monitoring Yellowstone for USGS, revealed a diagram during a lecture at Menlo Park, California, that showed the shockwaves produced.
He said in 2014: “The Denali earthquake occurred in 2002 and it was a magnitude 7.9 that occurred on the Denali Fault up in Alaska.
Because the surface waves that were coming from that earthquake were so big, even down in Montana and Wyoming, that the seismometers couldn’t record the data
“Any time you have an earthquake, especially on a strike-slip fault, you’ll get surface waves produced.
“Those are the ones that do a lot of damage to buildings.
“And in the case of this particular earthquake, it sent big surface waves out in a southeasterly direction.
“Now even one of these little diamonds here represent a seismic station.”
Dr Lowenstein went on to explain how seismometers near Yellowstone failed to record the impact.
He added: “The ones that are red are ‘pegged-out’.
“They’re clipped data because the surface waves that were coming from that earthquake were so big, even down in Montana and Wyoming, that the seismometers couldn’t record the data.
“There was too much shaking and so it’s what we call ‘clipped’.
“Whereas the blue stations, there was a little bit less ground surface wave movement down into California for example.
“These are figures from a paper by the University of Utah – Stefan Husen was the main author.”
Dr Lowenstein went on to explain how they discovered big earthquakes like these threaten to set off others.
He continued: “When the ground shaking got to Yellowstone, it set off small earthquakes, magnitude ones, two and threes, but they were felt.
“This is a remarkable example of something that wasn’t known about until the early Nineties.
“That is the phenomenon of triggered earthquakes.
“You can have an earthquake at one location and the waves that are moving around the Earth actually trigger earthquakes at other locations.”
Volcanoes typically erupt when molten rock, also known as magma, rises to the surface following the Earth’s mantle melting.
This usually happens when the tectonic plates are pulling apart or where one plate is pushed down under another.
However, supereruptions have been known to happen following large regional earthquakes as they trigger unrest at the nearby volcano.
This is why scientists feat another “big one” earthquake could be enough to trigger a supereuption.
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