The volcano—located in the North Pacific—has long been dormant, with its last eruption occurring in 1924.
The aquifer stretches from Massachusetts to New Jersey—the biggest formation of its kind ever found.
Helium is a vital element in several industries, and a global shortage could have devastating effects.
Estimates of the size of North Korea's test in September 2017 place it between 70 and 280 kilotons of TNT equivalent.
The volcano famously experienced the largest caldera-forming eruption Europe has seen in the past 200,000 years.
Construction failures are thought to have caused the pit, which measures about 100 ft wide and 50 ft deep.
"You can clearly see the texture of the skin and scales, as well as four-toed claw marks, which are extremely rare," one scientist said.
The gem is roughly the size of a chicken egg.
"I don't think I've seen anything like it," said one seismologist.
The rocks are a missing link from a billion-year old supercontinent.
The research could help scientists understand natural disasters like landslides.
The "world-class" cave complex has a volume of 236 million cubic feet.
But they found that the core was softer than previously thought.
The park is one of the only places in the world where the public can search for real diamonds in their original volcanic source.
Seismologists may have to completely change their models for the area based on latest findings.
Geologists have proposed a new theory for how the British Isles were formed millions of years ago.
Mount St. Helens forms part of the Cascade Arc, a line of volcanoes that extends from British Columbia, Canada, to northern California
The eruption may have wiped out the ozone layer.
A 3D map of the planet shows the ancient configurations of the oceans and continents, and how they have changed over time.
The latest results could help to improve earthquake forecasting in the short term.
A supervolcano is a large volcano that has had an eruption of magnitude 8 or more
Scientists found that Mars's crust formed much earlier than previously thought.
When the Pine Island Glacier melts, it could trigger even more ice to melt and raise global sea levels.
In 1906, a powerful 7.9 magnitude earthquake caused the deaths of up to 3,000 people and destroyed more than 80 percent of the city of San Francisco.
Geologists have identified a new type of fault movement at San Andreas.