Supervolcano fears: "Big One" come

The amazing California "seismic break" is over. He should already have had several "fat" now. All this pressure has to go somewhere. Now geologists are nervously watching eight nearby volcanoes. And why is the Yellowstone Supervolcano acting so strange?

The US Geological Survey (USGS) has warned Southern California to expect more major earthquakes. Some, they say, might even be more powerful than those experienced in recent days.

"(These earthquakes) do not make (the Big One) less likely," said Lucy Jones, a local seismologist, at the Los Angeles Times. "There is about a one in 20 chance that this place is experiencing an even bigger earthquake in the next few days, and that we have not yet seen the biggest earthquake in the sequence."

In part, it's because California has long been waiting for "the big one".

The last century has been unusually calm with regard to major earthquakes.

The latest "Big One" dates back to 1906, when a 7.9-strong earthquake realigned San Francisco real estate.

And American geologists are beginning to think that it's not just a stroke of luck.

Something deep beneath California seems to be changing. And its implications must still be understood.

SILENCE OMINOUS

Last week's earthquakes are the largest in Southern California since 1999. Then, a magnitude 7.1 event hit the distant Mojave Desert.

It was an isolated event. And it was not a surface earthquake either.

"We are unusually silent," co-wrote Glenn Biasi, co-author of a recent study, on a seismic hiatus at the earthquake, on Live Science in April. "The biggest mistakes and fouls for most of the slip have not been corrected."

Something broke the geological pattern.

The USGS has carefully examined the California terrain for traces of past earthquakes. They know how many lives could potentially be at stake. And warned, it's forerunner.

They collected 1000-year-old seismic recordings at 12 key sites along the main Golden State fault lines – the extended San Andreas Fault, the Hayward Fault and the San Jacinto Fault.

These data reveal that the probability that the three faults will be silent for 100 years is practically nil.

According to the USGS study, California should have expected about six "Big Ones".

"We do not think this has happened in the last thousand years," Biasi said.

The "hiatus" of the earthquake remains a mystery. The speculation that the faults simply evacuated much of their accumulated tension in the exceptionally active nineteenth century remains this speculation.

Another possibility is that there is something deeper, so great that it causes the "synchronization" of the activity of the five main fault lines of the state.

EXPLOSIVE IMPLICATIONS

"In California, the risks of damage from earthquakes, landslides, floods, tsunamis and forest fires are widely recognized," says another recent report from the USGS. "The same can not be said of volcanic eruptions, even though they occur in the state as often as the larger earthquakes on the San Andreas Fault."

Of the eight volcanoes in the state, seven found themselves sitting above "active" magma chambers.

Disturbingly, some 200,000 people are classified as "at risk" in the event of an eruption. And he argues that there is a 16% chance that such an event will occur in the next 30 years.

Like fault line studies, geologists have drawn evidence from the Californian landscape to determine volcanic activity over the past 5,000 years.

It has been discovered that five volcanoes – Mount Shasta, Medicine Lake, Lassen, Long Valley and Salton Buttes – have erupted over the past 3,000 years. The Clear Lake volcanic field near San Francisco – although considered potentially very high risk – did not explode any longer.

The trick is to predict when the next eruption is likely to occur.

It is an inexact science. But there are clues.

GPS sensors and satellite radars are used to measure the deformations of volcano surfaces. Seismometers detect underground movements. Gas emissions are regularly tested to check for changes in content.

Until now, the eight remain silent.

Basic question

The melted heart of the Earth is always moving. Crustal movements are thought to lie behind the moving magnetic field of the North Pole. A magnetic "anomaly" in the South Atlantic even gives some satellites a headache.

The geysers of Yellowstone National Park, located above the world's largest "supervolcan", have acted erratically.

Is there a link?

Seismologists say that there is simply no evidence to support that. And a surface earthquake in California will have no impact on Yellowstone, about 1,000 km away.

But speculation persists: social media is flooded with supervolcanic discussions.

So what do the experts think? The USGS unit specifically tasked with overseeing the famous geysers and the monster lurking beneath was baffled by the shifting motions of normally normal geyser eruptions.

With regard to the activity of the huge magma chamber located far below, little has changed. Instead, it is thought that changes in a "crystal slurry" in the Yellowstone chamber distort the hydrothermal channels feeding the park's greatest attractions.

And, although the last Yellowstone supervolcan eruption was a shocking event, it should not blow for hundreds of thousands of years.

This story originally appeared in news.com.au.