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Volcanic Hazards

June 10, 1999

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.

A volcanologist's commute

If you ask volcanologists what the most dangerous part of their job is, they are likely to answer, "flying in helicopters." Of course, the helicopter pilots who ferry us to the field would disagree strongly with that assessment, but the fact is that flying through the horrible weather that Kilauea's east rift zone regularly dishes out can be a hair-raising experience, not to mention skimming over fields of active lava and landing next to fountaining vents.

But most of our flights are routine, and that's good, because we rely heavily on helicopters for much of our work. The beauty of a helicopter is that it can land almost anywhere, although that doesn't mean that it's a piece of cake for the pilot. Try finding a level spot on a fresh `a`a flow!

On dry days, cinders and fine-grained bits of volcanic glass on the ground pose a problem, because helicopters create a mini-tornado when they land, whirling loose debris into the air, where the grit can damage rotor blades and sandblast windows. Often pilots will briefly hover a few feet above the ground before landing, letting the downwash from the rotor blades sweep away the glassy fragments.

Probably the greatest hazard to helicopters flying near Pu`u `O`o comes from the gas plumes that rise from vents, lava tubes, and the shoreline where lava enters the ocean. These plumes contain corrosive acids and particulates that can be sucked into the engine and cause serious damage. All pilots who fly near the eruption site have to adapt their routes to stay upwind of these noxious clouds.

HVO employees are required to take helicopter safety training every few years and to wear special protective clothing, including helmets and flame-retardant flight suits, when we fly. Most of us keep the flight suits on after landing. Though they weren't intended for this purpose, the suits serve double duty by providing some protection from the heat near skylights and from molten spatter. If flying bits of lava touch our clothes, at least they won't start burning.

We've flown with many pilots over the years and have met some interesting characters along the way. Take the pilot we were out with last week, for example. Raised on O`ahu, David Okita gets up before dawn most days in order to get in a little surfing before heading for the hangar. David first flew a helicopter at age 12, with his dad at the dual controls. He subsequently went off to the mainland to earn a degree in economics but soon came back to the islands to take up a career in the air.

David began flying on the Big Island 15 years ago, during the Mauna Loa eruption of April 1984. He's logged countless hours looking down on the current eruption of Kilauea but is far from being bored with it all. When he's out in the field with us, David is continually asking astute questions about the eruption. By now, he probably knows enough to qualify for a degree in geology! Next to the eruption, his favorite topic of conversation is where to find the best plate lunch on the island.

We rely on helicopter pilots for information on days when we're stuck in the office, too. Many tour pilots have been flying over Pu`u `O`o for so long that they are quick to spot any changes in the activity, and we always appreciate getting their reports.

Eruption Update

There were no changes in the eruptive activity of Kilauea Volcano during the past week. Lava continues to erupt from Pu`u `O`o and flow through a network of tubes from the vent to the sea. Lava is entering the ocean near Kamokuna and enlarging the bench. The public is reminded that the ocean-entry area is extremely hazardous, with explosions accompanying unpredictable collapses of the new land. The steam clouds are highly acidic and laced with glass particles.

Two earthquakes were reported felt during the week ending on June 10. A magnitude-3.9 aftershock of the April 16 Wood Valley earthquake was felt by residents of Pahala and Wood Valley at 7:20 a.m. on June 7. The earthquake was located 6.5 km (3.9 mi) northwest of Pahala at a depth of 7.7 km (4.6 mi). Residents island-wide were awakened by a magnitude-4.4 earthquake at 3:22 a.m. on June 10. The epicenter of the earthquake was 21.3 km (12.8 mi) southeast of Punalu`u at a depth of 52 km (31.2 mi).

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Updated: 14 June 1999