The science behind Hawaii's Kilauea volcano and 2,200-degree lava

WASHINGTON -- Hawaii's Kilauea is not your typical blow-the-top-off kind of volcano. It's been simmering and bubbling for about 35 years, sending superhot hot lava spewing up through cracks in the ground. This month's eruptions are more of the same, except the lava is destroying houses miles from the summit.

The lava has already devoured more than two dozen homes in and around the neighborhood of Leilani Estates, reports CBS News' Carter Evans. By helicopter, he pointed out that you can see the destruction, but there aren't any firefighters nearby because there's nothing they can do.

Scientists said Monday there's been a slight decrease in the pressure that forces lava to the surface, but it's likely a temporary lull. Dennison University volcanologist Erik Klemetti said similar eruptions at Kilauea have simmered for years.

"It's going to take some time before you can say for sure whether things are winding down," he said.

Nonstop eruptions

Kilauea is the youngest and most active of the five volcanoes on the Big Island. It's been erupting continuously since 1983, but not the way most people think, not like Mount St. Helens in 1980, spewing straight up and everywhere.

A couple of miles below Kilauea is a constantly fed "hot spot" of superhot molten rock from deep inside Earth. It needs to find a way out. Rather than exploding, at Kilauea "you get an oozing of lava at the surface," explains U.S. Geological Survey volcano hazards coordinator Charles Mandeville.

The molten rock is called magma when it is underground; when it reaches the surface, it is called lava. The lava flows out through cracks in the ground, usually within the confines at the national park that surrounds Kilauea (pronounced kill-ah-WAY'-ah). But this time the eruptions are destroying homes.

"This kind of eruption that is occurring now is very normal for this volcano," volcanologist Janine Krippner of Concord University in West Virginia. "It's really that it's just impacting people."

What happened this time

The past week or so has seen "a major readjustment with the volcano's plumbing system," Mandeville said.

On April 30, scientists got their first sign something was up. The floor of the summit's lava pool had a "catastrophic failure," forcing the magma east, looking for ways out, Mandeville said. That created a series of small earthquakes.

The magma escaped in "fire fountains" of lava shooting as high as 230 feet (70 meters) out of cracks, Mandeville said. The first one of those happened last Thursday, followed by at least nine more since then.

"You don't know where the next fissure is going to open up," he said.

What's next

While there's been a slight decrease in pressure, scientists won't know for certain if Kilauea has calmed down for at least two months, according to Mandeville. He said it could be much longer before conditions are safe for people to be in the area east of the volcano's summit. Officials have told some 1,700 residents to leave their homes.

The lava is 2,200 degrees (1,200 degrees Celsius), Mandeville said.

"It literally incinerates anything it touches," he said.

It's not just the molten rock, but the spewed gases can be dangerous too, Klemetti said. That includes sulfur dioxide, which reacts with water in your lungs and can form acid, he said.

Mandeville said scientists want at least two months of calm before declaring the situation better.

In the meantime, "there's not much we can do other than get people out of the way," he said.

Volcanoes make Hawaii

The Hawaiian Islands only exists because of volcanoes. These volcanoes were created from "hot spots" of underground magma, which are mostly but not always underwater. The molten rock erupts on the sea floor, cools and forms a volcano. With each eruption, the volcano grows until it is big enough to push out of the water and form islands.

There are about 13 hot spots like this around the globe with the islands of Hawaii one of the most active of the bunch.

Nine-tenths of Kilauea's surface is less than 1,000 years old, which is quite young in geology, Krippner said.

Mandeville said there are 169 active volcanoes in the United States - including underneath Yellowstone - and 1,550 in the world that are above sea level, he said.

We wouldn't exist without volcanoes, scientists said. Volcanic eruptions provide nutrients, like nitrogen, for soil and their gases, especially water vapor, helped form the atmosphere we now have.

"It provides so much good," Krippner said, "we just have to get out of their way while they do their thing."