Volcano monitoring and eruption warnings

Robert I. Tilling
Volcano Hazards Team, U.S. Geological Survey, MS-910, Menlo Park, CA 94025-3591, USA.
Tel. : +1-650-329-52 28, Fax: +1-650-329-52 03,
E-mail: rtilling@mojave.wr.usgs.gov

Volcanic unrest whether or not it culminates in eruptive activity typically involves physical and (or) chemical changes in the state of the volcanic system. The systematic visual observation and instrumental measurement of such changes (i.e., volcano monitoring) constitute the scientific basis for eruption warnings and development of hazards-mitigation strategies (McGuire et al., 1995; Scarpa and Tilling, 1996). Specifically, volcano-monitoring data permit the early detection of excursions from "normal" (i.e., baseline) behaviour that might augur eruption and attendant hazards at active and potentially active volcanoes.

Since 1980, with the reawakening and eruption of Mount St. Helens (Washington, U.S.A.), tremendous advances have been achieved in volcano-monitoring techniques (both ground- and space-based) and in data acquisition, analysis, and interpretation. Particularly exciting has been the improvement in techniques of continuous, "real-time" or near "real-time" monitoring of precursory seismic, geodetic, and geochemical phenomena, holding the promise of increased availability in the 21st century of robust and reliable early warning systems (EWS) to mitigate hazards at high-risk volcanoes.

In general, the longer the period of volcano monitoring by an EWS, the more diagnostic and reliable is the detection of possible eruption precursors. However, the successful experience in responding to the powerful 1991 eruptions of Mount Pinatubo (Newhall and Punongbayan, 1996) attests that, even with unrest already in progress, the immediate initiation of volcano monitoring-by rapid deployment of a mobile volcano-monitoring system (Murray et al., 1996)-may still result in timely eruption warnings and life-saving evacuations of people at risk, even at a previously unmonitored volcano. But we must never forget the sobering lesson from the 1985 tragic catastrophe at Nevado del Ruiz (Colombia): No matter how precise and abundant the monitoring data, and how rapidly they are collected and analysed, the most sophisticated EWS is rendered useless if scientists fail to communicate hazards information-quickly and effectively in understandable language-to emergency-management officials so that mitigation measures can be implemented in time to avert disaster.

McGuire, Bill, Kilburn, Christopher, and Murray, John, 1995, eds., Monitoring Active Volcanoes: Strategies, Procedures, and Techniques: University College London Press, 421 pp.

Murray, T.L., Ewert, J.W., Lockhart, A.B., and LaHusen, R.G., 1996, The integrated mobile volcano-monitoring system used by the Volcano Disaster Assistance Program (VDAP), in Scarpa, Roberto, and Tilling, R.I., eds., Monitoring and Mitigation of Volcano Hazards: Springer-Verlag, Heidelberg, Germany, p. 316-362.

Newhall, C.G., and Punongbayan. R.S., 1996, eds., Fire and Mud: Eruptions and Lahars of Mount Pinatubo, Philippines: Philippine Institute of Volcanology and Seismology, Quezon City, and University of Washington Press, Seattle and London, 1126 pp.

Scarpa, Roberto, and Tilling, R.I., 1996, eds., Monitoring and Mitigation of Volcano Hazards: Springer-Verlag, Heidelberg, Germany, 841 pp.