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On May 2, 2018 the cracks were only a few inches across, innocuous to the casual observer, not even slicing fully through the black asphalt in the neighborhood of Leilani Estates. To someone from anywhere else in the United States, they would look like the ordinary wear and tear of an aging blacktop. But this was Hawaii, on the flanks of an active volcano. Earthquakes had just shuddered east toward the neighborhood from the eruptive vents at the summit.

The people who lived here knew that there was a very good chance the cracks were a sign of something more dangerous brewing beneath the pavement. They called researchers at the Hawaiian Volcano Observatory, who came out to take pictures of the cracks, measure them, and check to see if there was any heat or steam coming out. There wasn’t—yet. The cracks were the result of reservoirs of molten rock (magma when under the ground, lava when it pours forth on the surface) moving beneath the roads and houses and lush green vegetation.

cracks
A USGS researcher stands near cracks in the road in Leilani Estates on May 2, 2018. U.S. Geological Survey

Late the next afternoon, the thing the cracks heralded broke forth onto the surface, starting with white and blue fumes steaming from the ground followed by orange splatter. In under two hours a fissure 492 feet wide sliced through the subdivision, forcing residents to evacuate. But for the researchers, it was time to go to back to work.

Since the eruption started last week, they’ve been at it 24/7, taking shifts to keep a constant eye on the eruption’s progress. That’s where many of those amazing images and videos of creeping, bubbling, incandescent roadblocks, fiery fountains, and blackened gashes across verdant landscapes comes from.

It takes a lot of work to get those photographs to the public. And the visual documentation, from those tiny cracks to furious fissures, is only a small part of the volcano monitoring process. The researchers are also gathering immense amounts of data on the current eruption, tracking how and where it moves, communicating their findings with local authorities to keep people that live in the area around there safe, and taking measurements and samples for scientific research.

Unsurprisingly, with an eruption going on right now, the researchers weren’t available to sit down and chat about their work. They’re out watching fissures form, keeping well away from splattering bits of molten rock and getting data that could help the rest of us understand this eruption better.

And that means taking some important precautionary measures.

“When our scientists go into the field to monitor the volcano, safety starts with the clothes they wear. They wear long-sleeve shirts and long pants, all in cotton or other natural fibers. Synthetic fibers melt and do horrible things if exposed to significant heat, such as radiant heat from lava,” Leslie Gordon, a Public Affairs Specialist and geologist with the U.S. Geological Survey, told Popular Science in an email. The USGS runs the Hawaiian Volcano Observatory, and their scientists are the ones sending back reports from the field.

black lava steaming with an orange skylight in the middle, surrounded by forests
An aerial view of lava flows in Leilani Estates. U.S. Geological Survey

“They wear gloves in case they stumble; the lava shards are sharp like broken glass,” Gordon says. “They wear sturdy boots, with stitched-on soles. Glued-on rubber soles can melt and end up like clown shoes when exposed to the heat of lava. There is a significant amount of radiant heat coming from fresh lava (like sticking your head in an oven). You donʻt need to actually touch the lava to get burned.”

Man in vest and mask standing next to burning ground.
A HVO geologist stands next to a fissure on May 8, 2018. The light of molten rock could be seen about 3 feet below the surface. U.S. Geological Survey

Of course, the safety precautions that the scientists take vary with the situation and the risks involved. They might wear a helmet to protect their heads from lava bombs—a technical term for blobs of airborne molten rock. In many cases, they wear respirators to filter out the dangerous gas sulfur dioxide that comes out of the vents, and carry monitors with them to measure levels of the gas.

For helicopter flights—where they take both thermal and visual images of the lava flows—Gordon says an entirely different set of safety rules come into play. Even high above the earth, researchers wear fire-resistant flight suits, helmets, and gloves.

sample
A researcher collects samples of recently erupted rock from near one of the recent fissures that erupted in Hawaii. U.S. Geological Survey

But images and remote data will only get you so far. If an image is worth a thousand words, rocks can be worth a thousand images. To get a better idea of the conditions deep inside the planet that precipitated this eruption, researchers take samples, picking up hardened bits of blackened basalt that have landed on lawns and roadways, or even digging the pointy end of a rock hammer into a still-runny lava flow.

Take a look at the process from a first-person perspective here, in a video taken during a 2015 eruption:

At the site of the current eruption, the researchers are busy installing seismometers to measure ground shaking in the area, which could tell them more about how the magma is moving under the surface. They join a network of other seismometers places throughout the region that are now under constant surveillance. Tiltmeters higher up the mountain on Kilauea measure how the magma there is deflating or inflating the slopes as webcams watch the surface of the lava lake on the summit drops dramatically feeding the eruptions at Leillani.

This particular eruption shows no signs of abating, and even when it does, the volcanologists will keep up their constant monitoring. The researchers peer into fissures to see if they can spot signs of heat before it reaches the surface, and keep an eye on any changes, even ones as small as a few new cracks in the pavement.

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