The earthquake swarm at Yellowstone has reached a nearly unparalleled number. Since June, seismologists have measured almost 2,500 tremors, one of the longest streaks on record.
In September alone, the University of Utah’s Seismograph Stations monitored 115 earthquakes, with the largest in the month measuring a magnitude of 2.3. Over half the quakes occurred in the western region of Yellowstone.
According to the U.S. Geological Survey (USGC), the earthquake swarm in Yellowstone started on June 12. Since then, instruments have recorded 185 tremors around a magnitude 2, 12 in the magnitude 3 range, and one at 4.4. Most were tremors less than magnitude 1.
Earthquake swarms, like the one currently happening in Yellowstone, occur when multiple tremors are measured in one area over several months, without a defined series of events. Usually, one massive earthquake will strike a region, then numerous aftershocks will follow.
While the number of quakes has slowed since August, USGC seismologists aren’t sure the earthquake swarm is over. Mike Poland, lead scientist at the USGC’s Yellowstone Volcano Observatory, told Newsweek that it is a “bit too soon” to come to any definite conclusions. He is not ready just yet “to declare it over.”
From June to the end of September, scientists have officially measured 2,475 earthquakes. However, Poland said that number would likely increase as scientists sort out the data and “crunch the numbers” over the next few months. Often, small earthquakes will overlap each other, making it appear as one quake instead of many to seismographs.
The ongoing earthquake swarm in Yellowstone will likely emulate another series of quakes that occurred in 1985 when over 3,000 tremors were measured in three months. While the current streak appears high, scientists aren’t concerned, as these types of swarms are common in the Yellowstone area.
Whenever the USGC releases data about an earthquake swarm, fears of a Yellowstone supervolcano eruption quickly spread. Yet, scientists say the seismic movements in the area are unlikely to trigger any serious volcanic activity, stressing the current alert level is “normal.”
If scientists are wrong and the Yellowstone supervolcano does erupt, the explosion is estimated to be 1,000 times stronger the May 1980 eruption of Mount St. Helens in Washington. Despite the fears brought about by the earthquake swarm, there have been no other signs of an imminent eruption that typically accompany such an event like “ground uplift” around the caldera, according to the USGC. Estimates put the annual chance of a supervolcano eruption at one in 700,000.
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