Scripps Researchers Map Vast Underwater Volcano the Size of San Diego County

SAN DIEGO — When it comes to volcanoes, the real action is underwater. The volcanoes lining tectonic ridges along the ocean floor are much more active than ones on ground. In fact, they're the most active in our entire solar system. And the magma that pours from them is constantly creating new seafloor.

This well of magma chambered deep within the Earth's mantle beneath the Pacific Ocean is 100 miles deep and 100 miles wide.

This well of magma chambered deep within the Earth's mantle beneath the Pacific Ocean is 100 miles deep and 100 miles wide.

So, where do these volcanoes get all their magma?

In a study published in Nature this week, Scripps Institution of Oceanography researchers used electromagnetic technology to map a huge well of magma fueling underwater volcanoes in the Pacific Ocean.

They studied the mantle beneath the East Pacific Rise, a tectonic ridge that turns into the San Andreas fault once it reaches California. The electromagnetic sensors the scientists used to collect data have often been often harnessed to find offshore oil for energy companies.

Lead author Kerry Key said the magma deposit his team imaged turned out to be even bigger than previously thought.

"If we were to actually take the image that we've made and lift it over say a Google map of San Diego county, the molten region would be as wide as San Diego county," he said. "So this is a really gigantic seafloor volcano."

The researchers' findings could be used to help better understand volcanoes at sea and on land. KBPS