Yellowstone volcano eruption: Is Yellowstone eruption imminent after earthquake swarm?

More than 200 tremors have struck the Yellowstone supervolcano over the past few days.

The swarm of earthquakes began on February 8 and “increased markedly” on February 15, the US Geological Survey said.

However Mike Poland, USGS research geophysicist, said swarms like this account for more than 50 percent of the seismic activity at Yellowstone and he does not believe an eruption is imminent.

He said: “Before you read any more, keep in mind that swarms like this account for more than 50% of the seismic activity at Yellowstone, and no volcanic activity has occurred from any past such events.”

Normally 1,500 to 2,500 tremors occur during a year and the latest quake in the swarm measured 2.9 in magnitude on the Richter Scale.

All the earthquakes have occurred about 8km (5 miles) below the surface.

Yellowstone is one of two super volcanoes in the USA, the other is at Long Valley in California, it has had three major events in the past 2.1 million years.

These eruptions led to the creation of the calderas or large volcanic craters.

Hundreds of thousands of years have passed since Yellowstone last erupted, which led to the creation of the West Thumb Geyser Basin and extended the Yellowstone lake.

Scientists believe the supervolcano will not erupt any time soon and odds of an eruption happening within a given year are one in 730,000, according to the USGS.

The largest historic earthquake in the region happened in 1959 at Hebgen Lake, which was located just west of the park boundary and north of West Yellowstone and measured magnitude 7.3 on the Richter scale.

It claimed the lives of 28 people and triggered a major landslide in Madison Canyon, which led to the creation of Earthquake Lake.

However it is not the earthquake that is most troubling but the possible resulting eruption of Yellowstone. 

A huge magma chamber is situated beneath the giant Yellowstone Caldera and if it erupted it would have an extreme effect on the surrounding areas.

The eruption could emit ash that would expand over 500 miles and cover the ground with as much as 4 inches of gray ash.

An explosive eruption on this scale can alter climate on a global scale for years afterwards and even decades and the super volcano would spew gases, including sulfur dioxide, a gas that can lead to acid rain and global cooling as it reflects the sun away from the Earth. 

The USGS said: “Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate.

“Fortunately the chances of this sort of eruption at Yellowstone are exceedingly small in the next few thousands of years.”