Impact of Volcanic Activity on Airports

Presented at 3rd International Workshop on Volcanic Ash, Toulouse, 29 Sept-3 Oct 2003

Marianne Guffanti, U.S. Geological Survey, 926A National Center, Reston, Virginia 20192, USA guffanti@usgs.gov

Gari C. Mayberry, U.S. Geological Survey, Washington DC 20560, USA mayberry@volcano.si.edu

Thomas P. Miller, U.S. Geological Survey, Alaska Volcano Observatory, Anchorage AK 99508, USA tmiller@usgs.gov

Contents

• Introduction
• Extent of the Volcanic Hazards to Airports
• Reducing Operational Disruption
• Summary
• References Cited

In addition to posing a hazard to in-flight aircraft from airborne volcanic ash, volcanic activity also can disrupt operations at airports, with both local and global consequences for modern life and commerce. Worldwide, approximately 500 airports lie within 100 km of volcanoes that have erupted since 1900 AD. The primary volcanic hazard to airports is ashfall, which causes loss of visibility, structural damage, contamination of ground systems and parked aircraft, and slippery runways. Accumulation of even a few millimeters of ash has caused temporary airport closures. On rare occasions, airports also have been damaged by pyroclastic flows (e.g., on the island of Montserrat, British West Indies, in 1997) and lava flows (notably, at Goma, Dem. Rep. of Congo, in 2002). Ash in airspace around airports has damaged in-flight aircraft (e.g., near Guatemala City, Guatemala, in 1999), and airport closures may involve loss of alternate landing sites required for operation of long-distance twin-engine flights (particularly for flights over the North Atlantic).

Ash-contaminated airports can operate with due caution. Practical operational guidelines, based on experience at numerous airports, have been published by ICAO (International Civil Aviation Organization, 2001) and the U.S. Geological Survey (Casadevall, 1993). At-risk airports should have such information on hand as a basic preparedness measure and consider developing specific operational plans for ashfall events.

A new compilation of airport and volcanic data by the U.S. Geological Survey's Volcano Hazards Program and the Smithsonian Institution's Global Volcanism Program illustrates the extent of the volcanic hazard to airports. Information about reported instances of airports affected by volcanic activity was gleaned from various sources, including news outlets, volcanological reports (particularly the Smithsonian Bulletin of the Global Volcanism Network), and previous publications on the topic (e.g., Casadevall, 1993). For each instance, information about the airport (such as latitude, longitude, country) and a brief description of the operational disruption have been compiled along with data on the volcanic source (such as latitude, longitude, eruption date, and degree of volcanic explosivity).

Analysis of the resulting database reveals that during 1944 to mid-2003, operations at airports in at least 70 cities, towns, and military bases in 20 countries (Table 1) were disrupted on 103 occasions by eruptions at 34 volcanoes. This is not a complete inventory of airport disruptions because incidents are not always reported; nevertheless, it is a good sample from diverse parts of the world. About 50% of the impacted airports are located within 100 km of the source volcano, but operations at airports as far away as 500 to 1700 km from the eruptive sources have been disrupted. Some airports have been affected repeatedly—viz., at Anchorage in the USA, Catania in Italy, Kagoshima City in Japan, Manado in Indonesia, Mexico City in Mexico, and Quito in Ecuador.

Table 1. List of cities, towns, and military bases in which airport operations were disrupted by volcanic activity, from 1944 to mid-2003, organized by country.

The 34 source volcanoes are in 14 countries (Table 2). The volcanoes that most often disrupt airports are Mount Etna in Italy, Sakura-jima in Japan, Popocatepetl in Mexico, and Soufriere Hills on the Island of Montserrat in the British West Indies. Soufriere Hills Volcano, although the source of relatively small ash clouds since 1995, has affected the most airports (11), which is not surprising given its proximity to many other islands with airports. Indonesia and the United States have the most volcanoes (5 each) reported to have caused airport disruptions.

Table 2. Volcanoes whose eruptions are known to have caused operational disruptions at airports, from 1944 to mid-2003, organized by country.

An important factor in determining whether an eruption will affect a specific airport is the wind field, including the seasonal wind pattern, at the time of eruption. For example, the prevailing winds in the South Pacific over the Mariana Islands are from east to west, so that most of the time ash from the May-July 2003 eruption of Anatahan Volcano was dispersed away from population centers lying south of the volcano. But on 23 May 2003, winds from Typhoon Chan-Hom pushed the ash plume southward, dusting Saipan and causing flight cancellations there and at Guam, 320 km south of the volcano.

Forewarning of imminent volcanic hazards can reduce operational disruptions at airports. Methods of forewarning that have been used by airports include: (1) real-time detection of explosive volcanic activity; (2) forecasts of ash-plume paths; and (3) detection of approaching ash plumes using ground-based Doppler RADAR.

Real-time detection of explosive volcanic activity at Sakura-jima Volcano, Japan, allows use of the nearby airport in Kagoshima City despite the volcano's frequent eruptions (>7,300 eruptive events since 1955). Eruptive phenomena are monitored 24/7 and in all weather conditions with continuously transmitting seismic and infrasonic instruments designed to distinguish explosive, ash-producing eruptions from volcanic earthquakes and tremor without ash production. When the monitoring system detects an explosive eruption, a warning is automatically sent to flight dispatchers at Kagoshima International Airport. Dispatchers then check wind data and visibility and rapidly issue a recommendation to pilots (e.g., divert to another airport, maintain holding position, select alternate arrival route, or select normal arrival route). The monitoring/warning system used at Sakura-jima has proven very effective at reducing risks to aviation in an unfavorable volcanic environment (Onodera and Kamo, 1994).

Forecasts of ash-plume paths, based on ash-trajectory models for eruptions from proximal volcanoes, provided valuable forewarning to airport operators and the airline industry during the 1989-1990 eruption of Redoubt Volcano in Alaska (Murray and others, 1994). The Alaska Volcano Observatory (AVO) and the Anchorage Weather Service Forecast Office adapted a NOAA model that predicted plume trajectories for 3-hr intervals based on forecast wind fields. Before an eruption, the model was used to estimate where and when ash would be blown. Twice daily, after the predicted wind fields were updated, AVO would collect and plot the trajectories predicted for the next 72 hours. These trajectories were immediately available when an eruptive event occurred and were distributed by fax to all interested parties who could then act accordingly to mitigate the effects of volcanic ash - for example, Anchorage airports could optimize the times that runways were kept open. In general, for airport needs, ash-dispersion and trajectory models should have the capability to: indicate where ash would go in the first one to two hours after an eruption; estimate arrival time of ash at a particular location in addition to ashfall thickness; and deal with small- to moderate-sized recurring eruptions with little ashfall as well as major ash-producing events.

Detection of approaching ash plumes using ground-based Doppler RADAR was applied in Mexico City, located about 60 km from Popocatepetl's summit and within the volcano's ash-hazard zone. In 1997, Mexico's National Center for the Prevention of Disasters (CENAPRED) and the U.S. Geological Survey used an experimental ground-based Doppler RADAR to track the direction and speed of ash plumes, especially when visual confirmation was difficult at night and in bad weather. When the combination of seismic and RADAR data confirmed an eruption had occurred, alerts were given to air-traffic controllers at Mexico City International Airport to prevent ash-aircraft encounters around the airport. The experimental system used in Mexico eventually failed, and development of a robust system is needed for further volcanic applications.

Given the demonstrated vulnerability of airports to disruption from volcanic activity, high-risk airports should have basic preparedness information on hand, develop specific operational plans for ashfall events, and evaluate appropriate systems that can provide forewarning of imminent volcanic-ash hazards.

Casadevall, T. J., 1993, Volcanic Ash and Airports - Discussion and Recommendations from the Workshop on Impacts of Volcanic Ash on Airport Facilities: U.S. Geological Survey Open-File Report 93-518, 52 pp.

International Civil Aviation Organization, 2001, Manual on Volcanic Ash, Radioactive Material, and Toxic Chemical Clouds: Doc 9691-AN/954.

Murray, T.L., Bauer, C. I., and Paskievitch, J., F., 1994, Using a personal computer to obtain predicted plume trajectories during the 1989-1990 eruption of Redoubt Volcano Alaska: U.S. Geological Survey Bulletin 2047, p. 253-256.

Onodera, S., and Kamo, K., 1994, Aviation safety measures for ash clouds in Japan and the system of Japan Air Lines for monitoring eruptions at Sakurajima Volcano: U.S. Geological Survey Bulletin 2047, p. 213-219.

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