Nearly 2,500 Earthquake Tremors Have Been Observed Near Yellowstone Supervolcano Since June
Credit: ScienceAlert
Approximately 2,475 tremors have been recorded at Yellowstone since June, making it one of the biggest earthquake swarms in history. In September alone, there have been 115 earthquakes in the western part of the national park.
According to the Daily Mail, the largest swarm ever to occur at Yellowstone took place in 1985, with more than 3,000 events over a three month period.
Wikipedia describes an earthquake swarm as the following:
"...Events where a local area experiences sequences of many earthquakes striking in a relatively short period of time. The length of time used to define the swarm itself varies, but may be of the order of days, weeks, or months. They are differentiated from earthquakes succeeded by a series of aftershocks by the observation that no single earthquake in the sequence is obviously the main shock."
The biggest event in Yellowstone's most recent swarm occurred last month (September 4th at 8:59pm ET) and was recorded as a magnitude 2.3.
Mike Poland, a lead scientist at USGS's Yellowstone Volcano Observatory, said it is a "bit too soon to say whether the swarm has ended" in a Newsweek interview.
He said, "The activity has certainly waned drastically since August, and the swarm appears to be winding down, if not completely over. It will probably take a little while longer to declare it over."
Below are graphs showing GPS displacement data of 115 earthquakes originating in the western part of Yellowstone in September:
Regarding the activity, Poland further stated, "What we can say now is that through the end of September, the University of Utah has located 2,475 earthquakes in the swarm."
"This puts the 2017 swarm on par with that of 1985, which lasted three months and had over 3,000 located events. [This is] certainly a fascinating event and one that we hope to learn more about through some post-swarm analysis. There's a lot to work on this winter, for sure."
