Volcano Experts Seek Emergency Alert System
Imagine living in a place where, in the past 25 years alone, communities have been wiped out by lava flows; eruptions have flattened huge expanses of land and killed people miles away; and avalanches of volcanic debris have swept people to their deaths.If you live in America, you live in such a country.
The United States is among the most volcano-rich nations on Earth -- home to 45 eruptions and 15 cases of notable unrest at 33 volcanoes since 1980. But while a handful of hazardous mountains are relatively well-laden with monitoring equipment, many dozing giants are beyond scientists' electronic eyes and ears, posing a significant threat to thousands of people, according to the first comprehensive assessment of U.S. volcano risks.
And although about half of the 169 U.S. volcanoes capable of erupting are in relatively remote regions of Alaska, the danger that even they pose to Americans and others is not as small as many might suspect, says the report by scientists at the U.S. Geological Survey, the research arm of the Interior Department. That is because the plumes of ash that can spew undetected for many hours from unmonitored volcanoes are largely invisible to commercial airliner pilots and their radar but can quickly cause jet engines to fail.
Nearly 100 commercial jets are known to have inadvertently flown into volcanic ash plumes since 1980 at altitudes as high as 37,000 feet, including eight in which one or more engines shut down. Three 747s lost all four engines.
In every case, pilots managed to restart their engines -- albeit after harrowing drops in altitude. But those warnings should not be ignored, said geologist John Ewert, who prepared the report with co-workers Marianne Guffanti and Thomas Murray. "Three 747s have been turned into gliders, okay? And they are really lousy gliders."
The new report ranks every U.S. volcano on 15 "hazard" measures -- including history of activity and explosive potential -- and 10 "human exposure" measures, such as proximity to population centers and flight routes.
The team then calculated the level of monitoring each volcano deserves and performed a "gap analysis" that compares those levels to current monitoring levels.
Monitoring typically includes specialized seismographs that, unlike earthquake monitors, are tuned to detect vibrations caused by underground magma flows; ground- and satellite-based systems to detect bulges in the earth just a few inches high that typically precede eruptions; and devices to detect gas emissions and changes in groundwater levels or chemistry.
The team found that monitoring is strong, though has room for improvement, at the three U.S. volcanoes now erupting (St. Helens in Washington, Kilauea in Hawaii and Anatahan in the U.S. Pacific territory of Northern Mariana Islands) and the two volcanoes that seem closest to erupting: Mauna Loa in Hawaii and Spurr in Alaska.
It found worrisome gaps for 13 other "very high-threat" volcanoes and 19 high- or moderate-threat volcanoes that, despite posing serious dangers to aviation, have no real-time, ground-based monitors.