A cluster of earthquakes at the Yellowstone Park volcano is the most active it’s been in recent history. The earthquake count is up to 2,357 since June. The largest was a magnitude 4.4. The majority of the earthquakes were magnitudes of 0 or 1, as Newsweek reported.
Swarms of earthquakes do not necessarily reflect a forthcoming eruption. Yellowstone hosts thousands of eathquakes a year. The type of earthquake swarms that are occurring at Yellowstone are different from a regular earthquake, that indeed may signal an approaching eruption.
An earthquake swarm is more irregular. The series of earthquakes and aftershocks is less sequential and more random than those for a regular earthquake. Swarms occur when earthquakes occur irregularly, but with numerous occurring over a timeframe of weeks or months.
The current swarm is approaching the record set in 1985, when three months brought over 3,000 earthquakes. In 2010 a swarm brought over 2,000 earthquakes over a month.
The current situation doesn’t present too much of an eruption threat. The geological pressure would have to be sizable for anything to occur. “Yellowstone has had dozens of these sorts of earthquake swarms in the last 150 years it’s been visited. The last volcanic eruption within the caldera [crater] was 70,000 years ago. For magma to reach the surface, a new vent needs to be created, which requires a lot of intense geological activity,” said Jacob Lowenstern, one of the scientists managing the Yellowstone Volcano Observatory, via Newsweek.
Despite the activity, the U.S. Geological Survey has the volcano alert level at normal. It is impossible to predict when exactly a volcano will erupt. Scientists said the chances are one in 730,000 for Yellowstone over the next year.
Even if the earthquakes would lead to an eruption, scientists think it would not be of much consequence. “If Yellowstone erupts, it’s most likely to be a lava flow, as occurred in nearly all the 80 eruptions since the last ‘supereruption’ 640,000 years ago. A lava flow would be a big deal at Yellowstone, but would have very little regional or continental effect,” Lowenstern explained.
But for those hoping to see some action, a USGS report says, “Odds are very high that Yellowstone will be eruption-free for the coming centuries.”