February 22, 2007

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

Volcano Scientists Go to School to Learn How to Track Volcanic Ash

Ash blown from Redoubt Volcano, Alaska, nearly caused a 747 jetliner (KLM Flight 867) to crash. December 1989.

Scientists from the U.S. Geological Survey's Volcano Hazards Team are enrolled in a class to learn how to use radar to track volcanic ash clouds. "Radar" is actually an acronym for Radio Detection and Ranging. Radar may be familiar to you, because it is a system used by meteorologists to track weather systems or by law enforcement to catch people speeding.

Radar is just another tool in the volcanologist's kit to track volcanic hazards and mitigate disasters. In essence, the radar system uses radio waves to map the location, speed and direction of objects. In general, objects of interest could include aircraft, hurricanes, and rain squalls. For volcanologists, the objects of interest are pyroclastic flows, gaseous plumes, ash columns and ash fall.

Next to earthquakes, volcanic ash has the most far-reaching effects and is the greatest hazard from volcanic eruptions in the United States. Volcanic ash covers everything, creeps into openings, and is very abrasive. Airborne ash can cause temporary darkness by blocking out sunlight and reducing visibility. Ash is slippery, especially when wet, making roads, highways, and airport runways impassable. Its weight can cause roofs to collapse. Engines may come to a standstill from ash-clogged air filters, and moving parts can be damaged from grit and abrasion.

More than 80 commercial aircraft have unexpectedly encountered volcanic ash in flight and at airports in the past 15 years. Seven of these encounters caused in-flight loss of jet engine power, which nearly resulted in the crash of the airplane.

One of the most notable encounters of aircraft and ash occurred in December 1989 in Alaska. All four engines of a KLM jumbo jet shut down when the aircraft inadvertently entered a cloud of ash from Redoubt Volcano. The disabled jet was in a free fall from an altitude of 27,900 feet to 13,300 feet (a fall of more than 2 miles).

The crew of KLM Flight 867 struggled to restart the plane's engines. "Smoke" and a strong odor of sulfur filled the cockpit and cabin. For five long minutes, the powerless 747, with terrified passengers aboard, glided until the crew was able to restart all engines and land the plane safely at Anchorage airport. The plane required $80 million in repairs, including replacement of all four engines.

Dangerous and costly encounters between aircraft and volcanic ash happen because ash clouds are difficult to distinguish from ordinary clouds. Also, ash clouds can drift great distances from their source. For example, in less than three days, the ash cloud from the 1991 eruption of Mount Pinatubo in the Philippines traveled more than 5,000 miles to the east coast of Africa. This ash cloud damaged more than 20 aircraft, most of which were flying hundreds of miles from the volcano.

Pacific air routes are some of the busiest in the world, and at least 15 aircraft have been damaged since 1980 by flying through volcanic ash clouds. Such encounters worldwide have caused hundreds of millions of dollars in damage and lost revenue. Fortunately, no fatalities have yet occurred, but the growth in air traffic over volcanically active regions, such as the North- and Western- Pacific, is increasing the chance of a deadly encounter.

The scientists who are undergoing training will learn how to use the radar equipment to track volcanic ash. With this newly acquired knowledge they will be utilizing radar to prevent future encounters between aircraft and ash, making the skies safer around volcanoes.

If you want to know more about volcanic ash hazards see: http://pubs.usgs.gov/fs/fs027-00/

Activity update

This past week, activity levels at the summit of Kilauea Volcano have remained at background levels. The number of earthquakes located in the summit area is low (usually less than 10 per day are large enough to locate).

Eruptive activity at Pu`u `O`o continues. On clear nights, glow is visible from several vents within the crater. Lava is fed through the PKK lava tube from its source on the southwest flank of Pu`u `O`o to the ocean. About 1 kilometer south of Pu`u `O`o, the Campout flow branches off from the PKK tube. The PKK and Campout tubes feed two widely separated ocean entries, at East Lae`apuki and East Ka`ili`ili, respectively. Both entries are located inside Hawai`i Volcanoes National Park.

A third entry, fed by an offshoot of the Campout flow, has been active since December 26. It is located at Kamokuna, about midway between the two older entries. In the last week, intermittent breakouts from the Campout tube have continued on the slope of Pulama pali and on the coastal plain.

A new breakout from the main PKK tube has been advancing down the pali and across the coastal plain in the past month, more than a kilometer west of the Campout tube. Surface flows from this breakout continue to spread within the rope line above the East Lae`apuki entry.

Access to the sea cliff near the ocean entries is closed, due to significant hazards. The surrounding area, however, is open. If you visit the eruption site, check with the rangers for current updates, and remember to carry lots of water when venturing out onto the flow field.

Two earthquakes beneath Hawai`i Island were reported felt within the past week. A magnitude-2.4 earthquake at 9:51 a.m. H.s.t. on Saturday, February 17 was located 6 km (4 miles) south of Honoka`a at a depth of 10 km (6 miles). A magnitude-1.8 earthquake at 0:46 a.m. H.s.t. on Tuesday, February 20 occurred 14 km (8 miles) southeast of Waimea at a depth of 8 km (5 miles).

Mauna Loa is not erupting. During the past week, earthquake activity remained low beneath the volcano; five earthquakes were recorded southwest of the summit. Extension of distances between locations spanning the summit, indicating inflation, continues at slow rates.

Visit our Web site (hvo.wr.usgs.gov) for daily Kilauea eruption updates and nearly real-time Hawai`i earthquake information.