Volcano Watch — Forecasting lava flows and eruption clouds

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When lava flows from an erupting vent or from an active lava tube, scientists face the challenge of determining, or forecasting, which areas are likely to be covered by lava in the next few hours to days.

Forecasts are critical when lava flows threaten a community, highways, power facilities, and other infrastructure. For the past several weeks, forecasting the direction of lava flows at Kilauea have helped firefighters battle the Kupukupu fire in Hawai`i Volcanoes National Park.

As soon as scientists map active lava flows and estimate possible future flow paths, the information is given to officials of Hawai`i County Civil Defense and the National Park. The decisions and actions of these officials regarding public safety and possible evacuations are based, in part, on the current location and on forecasts of lava flows.

Disseminating information about an eruption in a timely manner is even more important when a volcano explodes and generates a column of ash and gas higher than about 8 km (25,000 feet) above sea level. Once airborne, the tiny ash particles are dispersed through different layers of the atmosphere. With wind speeds in the upper atmosphere frequently higher than 80 km per hour (50 miles per hour), an eruption cloud can spread hundreds of miles from a volcano--sometimes in different directions--in only a few hours.

We can easily understand the hazards to people and property from an advancing lava flow. But the hazards posed by eruption clouds and volcanic ash are not as intuitively obvious. Eruption clouds typically look like weather clouds and are not detectable by radar instruments currently in place aboard aircraft.

Volcanic ash consists of hard, sharp rock fragments and is highly abrasive. The ash particles easily scratch and erode plastic, glass, and metals on aircraft. Tiny glass fragments in ash can melt inside jet engines, resulting in the immediate weakening of engine performance and engine failure.

Thousands of aircraft fly through the air at cruising altitudes above 8 km (25,000 feet), and many of the world's air routes pass over Earth's most active volcanic regions. In the past 20 years, about 100 aircraft have encountered eruption clouds, and repair and replacement costs have exceeded $230 million.

Just as people must stay safely away from a fast-moving lava flow, jets must stay completely away from eruption clouds to insure their flight safety. This level of safety is achieved through international cooperation between government organizations and the airline industry.

When a modern jet travels at speeds above 840 km per hour (520 miles per hour)-about 14 km every minute (9 miles)-toward an eruption cloud or an erupting volcano, pilots must get information about an explosive eruption and the eruption cloud it produces as soon as possible. Airline dispatchers must also receive the same information so they can plan flights and evaluate hazards for aircraft already in the air and those getting ready to fly.

Scientists at the world's volcano observatories work hard to disseminate information about explosive eruptions in their region. Information about an eruption cloud-height, current location, and forecasts of future location-originates from many different sources, including pilot reports, various national meteorological and aviation organizations, and Volcanic Ash Advisory Centers.

Nine centers were created in 1995 to detect, track, and forecast the movement of eruption clouds within different areas of the world. The United States operates a center in Alaska and the Washington, D.C., area. Hawai`i lies within the Washington Volcanic Ash Advisory Center, which is also responsible for eruption clouds in the western United States, Mexico, Caribbean, Central America, and parts of South America.

Many visitors to Hawai`i look forward to viewing lava safely during the current eruption of Kilauea. If the volcano begins to produce explosive eruptions as it did in 1924 and between the 14th and 18th centuries, visitors and residents would appreciate information about eruption ash and clouds that can now be provided by the Washington Volcanic Ash Advisory Center in order to avert aviation disasters.

Volcano Activity Update

Eruptive activity of Kilauea Volcano continued unabated at the Pu`u `O`o vent during the past week. The "Mother's Day" lava flow is now pooling at the base of Paliuli with the distal end of the flow located 1.2 km (0.7 mi) from the ocean. The Chain of Crater road is open from 6 p.m. to midnight, and visitors can view the flow from a safe area. The sight of lava cascading down the pali is definitely unforgettable. Conditions of the Kupukupu fire determine access to the area, so it is best to check with the Hawai`i Volcanoes National Park (985-6000) before heading up.

The two flows emanating from the "rootless" shields are still active. The lower flow along the National Park-Royal Gardens boundary continue to inflate and spread on the coastal flats with only minimal movement toward the ocean. The mauka flow that entered the top of Royal Gardens subdivision two weeks ago has an active lobe moving down between Prince and Royal. The flow has passed Pikake and is approaching Plumeria. At least four houses are in the probable path of the flow.

There were no felt earthquakes during the week ending on June 13.