Strange Sounds THE LONG VALLEY CALDERA supervolcano is considered to be one of the world’s most dangerous, with signs that an eruption is “imminent” having surfaced across the Californian region.
Long Valley Caldera is a depression in eastern California that sits next to the Mammoth Mountain.
One of the planet’s largest calderas — a huge, cauldron-like hollow that forms after an eruption — it measures a staggering 20 miles long and 11 miles wide, and is up to 3,000 feet deep.
