Volcano Watch — Working on the volcano

As geologists working at the Hawaiian Volcano Observatory, we give many talks about the current eruption of Kīlauea, and people in the audience typically ask lots of questions about how volcanoes behave and how we attempt to predict that behavior. But they're curious about other things, as well. They frequently ask us, "What's it like to work on an active volcano? Isn't it dangerous to walk across brand-new flows? Do you ever fall through? What's it like up on Pu'u 'O'o?"

Let's start with the obvious: working on an active volcano is a HOT job. Walking across newly formed flows, such as the type that Kīlauea is currently erupting, is possible because the surface is supported by the molten material below. You have to wear thick-soled boots, and you don't stand around in one place for very long. If your boot soles are held on only by glue, you keep a close eye on them. When the glue starts to melt, it's time to beat a hasty retreat off the lava.

The main danger in walking around on these flows, however, is not to your feet, but to your brain. The first symptoms of heat exhaustion are a lot like those of hypothermia in freezing climates--you lose your ability to think clearly. When you stay out on the hot lava for a long period of time, either to map the flows or to make temperature or geophysical measurements, you work in pairs for safety.

It can be more nerve-wracking to walk over certain types of cooled flows--particularly the shelly pahoehoe that forms near vents. Walking on shelly pahoehoe is like walking on thin ice: you know that sooner or later you're going to fall through, and it's just a question of how far down you'll go. The skin of a pahoehoe flow is made of thin, flaky sheets of volcanic glass, and when you fall, it's like coming down on a pile of broken glass. You end up with deep cuts and scars that serve as a reminder to always wear heavy leather gloves.

Working on the rim of the Pu'u 'O'o crater is an act of faith. You have to believe that when you walk out to the edge to make a measurement, the piece of rim that you're standing on won't suddenly break away and collapse into the crater, or that an explosion from within the crater won't start lobbing bombs of molten lava and solid rock over the rim, or that an earthquake won't jolt the cone and open up new cracks beneath your feet. All of these events have occurred, but luckily not when anyone was on the rim.

When you work on Pu'u 'O'o, you always have to contend with the sulfuric fumes from the crater. You keep your gas mask fastened around your neck so that you can put it on quickly when the wind blows the fume in your direction. Sometimes the fume stings your eyes so badly that you're temporarily blinded, and you can't do anything but stand there until the wind shifts.

The worst conditions occur on rainy days, when Pu'u 'O'o is enveloped in a solid white cloud of steam. It's hard to always avoid bad weather, because the cone is located in one of the rainiest areas of the island. Sometimes you're trapped on the cone in a thick mixture of fog and fume, and it's frightening. You're caught between the rim of the crater on one side and a maze of impassable cracks and 'a'a flows on the other, and you can't see a foot in front of your face. You learn to keep your paths marked with brightly-colored surveyor's ribbon to help find your way down no matter what the weather.

Working on the volcano, you frequently feel an internal tug-of-war between fear and curiosity. But for experienced people with the right equipment and knowledge, plus a little common sense, the work isn't nearly as hazardous as most people assume.

Volcano Activity Update

The eruption from flank vents on the western side of Pu'u 'O'o continues. Lava tubes delivered lava to the ocean at three points--Kamokuna, Kamoamoa, and Lae'apuki--along a 2.3-km stretch of coastline within Hawaii Volcanoes National Park. The ocean entries were mostly nonexplosive. On the night of April 28, a large collapse of the Kamokuna bench removed a piece roughly 100 m wide by 400 m long.

Surface flow activity was concentrated on the coastal plain inland of the western entry points (Kamoamoa and Lae'apuki). No surface flows were observed above the 300-ft elevation.

There were no earthquakes reported felt during the past week.