There was a 4.5M earthquake in America yesterday. This wouldn’t be particularly newsworthy under most circumstances, except this time it was centered on Yellowstone National Park – famous for its supervolcano as much as its natural beauty.
Right off the bat, it’s safe to say that there is no reason to worry. It’s more likely than not that this quake – part of a swarm of tremors – was caused by magma moving harmlessly through the crust, hydrothermal fluids, or just the expansion of the regional crust by long-term processes.
“A light earthquake of magnitude 4.5 occurred at 06:48 PM on June 15, 2017 (MDT),” a press release by the United States Geological Survey (USGS) explains. “The epicenter of the shock was located in Yellowstone National Park, eight miles north-northeast of the town of West Yellowstone, Montana.”
It elaborates that the swarm of quakes began on June 12, “approximately thirty earthquakes of magnitude 2 and larger and four earthquakes of magnitude 3 and larger, including today's magnitude 4.5 event.” It is the largest quake in the region since March 30, 2014, when a 4.8M shook the park.
Listed as GREEN/NORMAL by the USGS, it’s clear that they are not expecting anything to come of this swarm. If anything, it’s a reminder that Yellowstone’s volcanic system is very much alive and well, and that one day it will erupt again.
We previously had a look at the world’s most dangerous “supervolcanoes”, which essentially describes eruptions that have the potential to be regional or planetary game-changers – bringers of chaos through an explosive, voluminous release of volcanic material. Yellowstone is seen as particularly dangerous in the minds of millions, but scientifically speaking, it’s not the most dangerous in the world.
It’s erupted catastrophically three times – 2.1 million, 1.3 million, and 640,000 years ago – with the second eruption getting the highest possible ranking on the Volcanic Explosivity Index (VEI) scale, a rough measure that denotes the power of a volcanic event. There have been minor lava flow-heavy eruptions between and since these three key events, but nothing to be concerned about.
It will erupt again someday, but will it be as powerful as those three paroxysms? It’s hard to say. The numbers suggest it is due for a sizeable blast in the next 50,000 years or so, but there’s just not enough data to say when exactly.
What we do know is that there is enough magma down there that could fill up 14 Grand Canyons to the brim, and the sudden release of all of this – in the form of lava, pyroclastic flows, and ash fallout – would amount to nothing less than a regional disaster, and possibly even a global one.
This earthquake serves as a reminder of this, but again, don’t panic. The chance of a “supereruption” taking place this year is just one in 730,000.