Yellowstone volcano: How USGS recorded ‘A LOT of activity’ near caldera – ‘they FELT IT!’
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.
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.
Jacob Lowenstein, who is in charge of monitoring Yellowstone for USGS, revealed a seismograph of the amount of activity on just one day – December 27, 2008.
He told students during a lecture at Menlo Park, California, in 2014: “These are seismograms and they are from the south and north end of the lake.
“All of the data is for December 27, 2008, and come from the Yellowstone Seismic Network.
But there were maybe 15 or 20 people who were living near the lake at the time and they felt it
“You have the time starting from early (top) to late (bottom) and each 15 minutes is represented by the black line – so four would be an hour.
“And these are all earthquakes, every time you get a squiggle you are looking at an earthquake.”
Dr Lowenstein went on to reveal how, although the earthquakes were not particularly strong, they were still felt in the park.
He added: “In this particular day, there was a lot of activity.
“The biggest one was a magnitude four, there were also ones, twos and three, a number of felt earthquakes.
“It was in December though, so there weren’t a lot of people around.
“But there were maybe 15 or 20 people who were living near the lake at the time and they felt it.
“It happened for about two weeks and the earthquakes were on a lineal trend.”
Dr Lowenstein revealed how USGS were left on edge six years earlier thanks to the Denali earthquake occurred in Alaska.
He said: “The Denali earthquake occurred in 2002 and it was a magnitude 7.9 that occurred on the Denali Fault up in Alaska.
“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.”
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