Latest study points to volcanic ash threat
Too many volcanoes are inadequately monitored, and timely warnings to aviators and other relevant officials of eruptions are necessary if ash clouds and other effects are to be avoided. To determine the priority of coverage, the U.S. Geological Survey (USGS) recently released a study, highlighting volcanoes that are currently under-monitored and pose a threat to aviation.
“We have learned from 25 years of experience to have monitoring in place before trouble starts,” said Marianne Guffanti, one of the authors of the USGS report. “The type and degree of monitoring needed was done by ranking the volcanoes by the threat that they pose.”
Then the volcanoes were assessed in terms of their current monitoring to outline where the needs are.
“For example, Mt. Shasta in California should be monitored at Level 4, but it’s Level 2,” Guffanti explained. Level 4 provides monitoring adequate to track detailed changes in real time; Level 2 provides monitoring frequently enough to recognize something anomalous is occurring.
Level 4 is needed for rapid notification to the aviation sector, where five minutes’ warning is needed. The five-minute criteria is based on the explosion of Mount St. Helens, when ash was hurled to the cruising altitude of jetliners in five minutes. The five-minute goal is the “gold standard” for reporting eruptions (see ASW, June 28, 2004).
“The five-minute warning that pilots received during the Mount St. Helens eruption in 2004 proved that the USGS system works,” said Capt. Terry McVenes, executive air safety chairman of the Air Line Pilots Association (ALPA). “That’s the kind of warning system pilots need for every volcano, and it can only happen through the USGS monitoring system.”
The USGS report highlights volcanoes in the U.S. that are currently not adequately monitored and pose a serious threat to aviation.
“You wouldn’t sail rough seas without a life preserver,” said Capt. Ed Miller, leader of ALPA’s Volcanic Ash and Aviation Safety Program. “We shouldn’t ignore volcanoes that we know are dangerously under-monitored.” Since 1980, almost 100 jets have inadvertently flown into volcanic ash plumes as high as 37,000 feet. In eight of these encounters, one or more engines shut down, and three B747s lost all four engines – although the pilots were able to restart them at lower altitude.
Of particular concern to ALPA are the active volcanoes in the Marianas Islands, a U.S. territory located in the North Pacific Ocean, which the USGS reports pose a significant threat to aviation. Only two of the volcanoes have some ground-based, real-time monitoring, and six volcanoes have no ground-based monitoring at all. The Marianas fall in the path of many U.S. flights bound for Hong Kong and Manila.
“One flight crosses over the Marianas Islands roughly every 22 minutes,” said Capt. Miller. “With so much at risk, the USGS needs to be equipped to conduct full monitoring of the Marianas volcanoes to protect the thousands of travelers flying across the Pacific.”
The danger comes from volcanic ash that can stay aloft for weeks. The ash is sucked into jet engines, melts and adheres to moving parts. If the encrustation is severe enough, it can cause the engine to flame out.
Volcanic ash also scours windshields so badly it can impede vision. In addition, volcanic ash interferes with radio communications, due to the high level of static electricity generated.
“The North Pacific averages five or six eruptions each year, with volcanic ash falling close enough to flight routes to become an aviation safety concern on as many as 12 days a year,” said Capt. Miller.
According to the USGS report, about half of the most threatening U.S. volcanoes are monitored at a basic level and a few are well monitored with a suite of modern instruments. Unlike most other natural hazards, eruptions herald their coming over periods of days to years with various physical and chemical indicators (called “unrest”) related to the rise of magma toward the surface of the earth. Modern instrumentation and data-processing techniques, combined with an understanding of the previous eruptive activity of a volcano, provide a means to monitor and interpret precursor signals – seismic, ground deformation, gas emissions, thermal changes, and the like – and make forecasts of the expected hazards.
Based on the USGS analysis of volcanic activity as of April 2005, the three highest priority targets for volcano monitoring improvements are:
1. The volcanoes erupting now – Mount St. Helens in Washington state, Anatahan in the Marianas Islands, and Kilauea in Hawaii – and the volcanoes that are showing periods of significant unrest – Mauna Loa in Hawaii and Mount Spurr in Alaska.
2. The 13 very high-threat volcanoes with inadequate monitoring: nine volcanoes in the Cascade Range of the western U.S., to include Rainier, Hood, Shasta, South Sister, Lassen, Crater Lake, Baker, Glacier Peak, and Newberry. Four Alaskan volcanoes in this group include Redoubt, Makushin, Akutan and Augustine.
3. Nineteen volcanoes in Alaska and the Marianas Islands pose a high risk to aviation, yet have no real-time ground-based monitoring to detect precursor unrest or the onset of an eruption.
The purpose of the USGS study was to determine where more robust monitoring is needed.
ALPA seeks congressional support for the USGS volcano early warning system, and for USGS to have the capability to implement the five-minute warning. The five-minute warning is considered essential because the ash can take only five minutes to reach altitudes above 20,000 feet, and aircraft can approach at rates of five miles per minute or 300 miles per hour, and pilots need time to divert and avoid the cloud.
The USGS will be submitting its plan for an integrated volcano early warning system with the fiscal 2007 budget cycle. The cost is estimated at $15 million to basically link sensors from the most hazardous volcanoes into a National Volcano Early Warning System. That’s not much “sticker shock,” given the nature of the threat. (The USGS report on volcanoes may be viewed at http://pubs.usgs.gov/of/2005/1164/)