Measuring the temperature of lava (somewhere between 1,500 and 2,000 degrees Fahrenheit) isn’t easy. Most thermometers either melt or just aren’t practical in the field, so other methods must be devised. Gansecki’s team took its samples to a nearby lab to run them through a device called an energy dispersive x-ray fluorescence spectrometer.
As lava cools, it crystallizes. So the researchers dunked the samples in water to stop the crystal growth. The team then dried and crushed the hardened lava to a powder and pressed it into pellets, which were bombarded with x-rays in the spectrometer. The x-rays cause elements in a sample to fluoresce at distinctive energy levels, making it possible to identify and measure them. The amounts of magnesium and calcium correlate with the lava’s maximum temperature.
Each set of samples took only about 20 minutes to run, and the chemical and temperature data was quickly relayed to scientists 35 miles away monitoring the flows on the scene.
The process proved an important predictor. After the initial eruption began, the temperatures began to increase, says Gansecki, and sometimes the hotter lava came out in unexpected places in the volcanic zone.
Meanwhile, at the volcano’s caldera, another research team was flying drones to collect digital images as the structure collapsed several hundred feet each day. “This was the world’s best-documented caldera collapse,” says Kyle Anderson, a US Geological Survey geophysicist. “We could really witness these processes at close range.”
An old lava lake at the summit of the mountain was connected to the shallow plumbing system of magma below, Anderson says. The caldera deflated as magma drained away from the summit, sort of like water down a bathtub with a 20-mile drainpipe. “The lava lake was dropping 150 feet per day,” says Anderson, who is the lead author on the second paper published today in Science.
He and his team used drone images and satellite data to assemble a three-dimensional digital map of the lake’s surface, which gave them valuable information about what was happening with the magma below; the height of the lake reflected the pressure of the reservoir below.
A third paper, published by the USGS’ Michael Patrick and colleagues, showed how magna surges in fissures far away changed the pressure in the caldera at the summit.
Because the Kilauea eruption happened in a place where so many scientists could work safely, and run back to their lab to analyze data quickly, the researchers say they learned a lot more than any other recent eruption. They’re hoping their studies will give them a better idea of how other volcano plumbing systems work, and how better to warn people who live nearby.
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