Author: Jennifer Leman / Source: Science News
After a stunningly volatile 2018, Hawaii’s Kilauea volcano, which had been continuously erupting since 1983, finally seems to be taking a break. Following 35 years of nonstop activity, no lava is currently flowing from the Big Island’s most famous volcano.
Scientists thought they knew Kilauea pretty well. It’s one of the most closely monitored volcanoes in the world, with instruments watching the volcano’s every move since the early 1900s. But the 2018 eruption still managed to offer up surprises.
“Everybody’s chewing on all the great data collected from this eruption,” says Christina Neal, the head scientist at the U.S. Geological Survey’s Hawaiian Volcano Observatory on the Big Island. “That will go on for years and years.” Neal coauthored a study published in the Jan. 25 Science describing some of the initial findings.
The latest episode started last May, as lava drained from the summit crater, flowing out at a rate of 50 meters per day. The molten rock gushed through underground tunnels and out linear eruption vents, or fissures, along an area called the lower East Rift Zone. By the time the eruption ended in August, Kilauea had destroyed more than 700 houses, covered 35.5 square kilometers of land and added almost 300 hectares of seafloor along the island’s southeast coast.
In addition, more than 825 million cubic meters of earth from the area around the summit crater collapsed, deepening Kilauea’s caldera. That’s enough material to fill about 300,000 Olympic-sized swimming pools, Kyle Anderson, a USGS geophysicist in Menlo Park, Calif., said December 11 in Washington, D.C., at an American Geophysical Union meeting.
With the massive collapse, the cliff-hugging Jaggar Museum, Hawaii Volcanoes National Park’s popular museum and research station, suffered damage and is closed indefinitely.
No one knows what’s next for the volcano, but five early findings from Kilauea’s latest outburst, described below, show some of Kilauea’s distinctive impacts.
FUME SIDE OF THE FISSURE
1. Really old lava explains why some fissures were extra explosive.
On May 13, lava suddenly exploded from a new fissure along the lower East Rift Zone. “There was this really loud banging that sounded like cannon shots,” says Christoph Kern, a geochemist at the USGS Cascades Volcano Observatory in Vancouver, Wash. Kern was working in the rift zone at the time.
Blocks of rock and ash flew hundreds of meters into the air. “It was reminiscent of a war zone,” Kern says. One man, who had not evacuated from his nearby home, suffered a shattered leg after he was struck by molten rock blasted from the fissure.
When the lava cooled enough for researchers to collect samples, the scientists were shocked. Kilauea “erupted a magma like we’ve never seen before” in Hawaii, says Cheryl Gansecki, a volcanologist at the University of Hawaii in Hilo.
“When I first got the analysis back, I told my student, ‘You’ve made a mistake; go do it again,’ ” she says. The molten rock was andesite, which is not usually found in Hawaii.
The Hawaiian Islands are dominated by basalt, a dark volcanic rock rich in iron and magnesium. Andesite contains more silica and gas bubbles than basalt. That extra gas makes eruptions extra explosive. Andesite is commonly ejected from volcanoes in regions where tectonic plates slip beneath one another, such as in the Andes in Chile or the Cascades in the Pacific Northwest. Hawaii, however, isn’t near a tectonic plate boundary; its volcanoes are fueled by a “hot spot,” a plume of magma that rises from Earth’s interior.
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| BIG BLASTS This video from May 16, 2018, shows explosions at fissure 17 of the Kilauea volcano. Researchers determined that instead of the basalt magma that feeds most Hawaiian fissures, this one also contained silica-rich andesite, which contains more gas bubbles than the basalt, making those eruptions extra explosive. |
The andesite was also much older than lava erupted from nearby fissures, Gansecki says. She suspects the andesite might have evolved from basaltic magma that was trapped underground during a previous eruption…
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