Fears of Yellowstone volcano eruption triggered by California earthquakes

After two strong earthquakes in California last week, internet searches for the Yellowstone caldera and volcano have increased. The earthquakes – respectively magnitude 6.4 and 7.1 on July 4 and 5 – had apparently caused fears of a supervolcan eruption caused by these events. According to Google Trends, related search terms include "California Earthquake" and "California's Greatest".

But these fears are totally unfounded, the USGS said. In an article posted on the website of the Yellowstone Volcano Observatory, scientist Mike Poland explained the impact of earthquakes on volcanic activity – and why California earthquakes do not would not cause an eruption of Yellowstone.

He said strong earthquakes are not uncommon in the western United States. The area is covered with fracture lines – an interactive map of these earthquakes can be found here. Fault lines are cracks in the earth's crust that can trigger earthquakes as they move.

"Since 1900, nearly 100 earthquakes greater than M6 have been reported in the United States and nine more above M7 (these two figures increase if we include Canada and Mexico)," wrote Poland . "Most of these events take place in California, but they have also occurred in Oregon, Washington, Nevada, Utah, Idaho, Montana, and Wyoming. assume that this rate is representative of the mean, it means that there would be about 10 M7 + events per century in the western United States ".

70,000 years ago, Yellowstone broke out for the last time. During this period, there could have been more than 7,000 powerful earthquakes, none of which led to an eruption in Yellowstone. Poland also said that the distance between the earthquake and Yellowstone was of little importance – in 1959, a magnitude 7.3 earthquake occurred on the border between Montana and Idaho, at the edge of the national park, but no eruptions had yet occurred.

Californian volcanoes

California also has its own volcanoes. The USGS recently released a report that the next big danger for the state could be a volcano rather than an earthquake – "The Potential for Earthquakes, Landslides, Floods , tsunami and damaging forest fires is widely recognized in California, "says the report. . "The same can not be said of volcanic eruptions, even though they occur in this state as often as the largest earthquakes on the San Andreas Fault."

There was no concern that the two strong earthquakes trigger an eruption on one of California's volcanoes.

The California Observatory of California Volcanoes released a statement last Saturday that a magnitude 5.4 earthquake (a replica of event 7.1) had triggered a swarm of earthquakes at the Coso Volcanic Field. However, the alert level of the volcano has been kept to normal and it is stated that there is "no imminent threat of eruption".

As Poland explains: "Earthquakes like those of last week are not likely to trigger volcanic eruptions, although they can trigger earthquakes on some far-flung big earthquake volcanoes." Some of these triggered swarms lasted for days. "

He added that strong earthquakes could also alter hydrothermal systems, including geysers in Yellowstone National Park. "But triggering eruptions? This is not common, especially in the United States," concludes Poland.

Following the earthquakes, concerns were also expressed about the outbreak of the "Big One". This is the idea that the San Andreas Fault – a 120km fault near San Francisco, Los Angeles and San Diego – is "expected" by a major earthquake.

This is based on the idea that there is an average lapse of time between major earthquakes on a given fault, as the pressure increases over time to the point where it is released. The last time a powerful earthquake occurred on the San Andreas Fault was in 1906, when a magnitude 7.8 earthquake struck the San Francisco area, causing considerable damage and hundreds, if not thousands of deaths.