Strategy for Reducing Volcanic Risk in the United States

Objectives of the Volcano Hazards Program

The overall objectives of the Volcano Hazards Program are to advance the scientific understanding of volcanic processes and to lessen the harmful impacts of volcanic activity. The Volcano Hazards Program monitors active and potentially active volcanoes, assesses their hazards, responds to volcanic crises, and conducts research on how volcanoes work to fulfill a Congressional mandate (P.L. 93-288) that the USGS issue "timely warnings" of potential volcanic hazards to responsible emergency-management authorities and to the populace affected. Thus, in addition to obtaining the best possible scientific information, the program works to effectively communicate its scientific findings to authorities and the public in an appropriate and understandable form.

The Volcano Hazards Program Five-year Science Plan, 1999-2003, describes the program elements listed below in more detail.

Five General Program Activities

1. Volcano Monitoring
2. Volcano Hazards Assessments
3. Volcano Crisis Response
4. Topical Investigations of Volcanic Processes
5. Scientific Outreach and Information Dissemination

Volcano Monitoring

Data collected by volcano-monitoring networks make possible the early detection of volcanic unrest and are indispensable for interpreting volcanic processes, forecasting eruptions, and predicting likely impacts of eruptions. The most effective monitoring is achieved by applying a combination of techniques (seismic, geodetic, hydrological, geochemical, and remote satellite analysis) on a continuous near-real-time basis. Monitoring contains an inherent research component by providing fundamental observations and measurements essential to develop and test models of volcanic processes and to improve monitoring methods.

Volcano Hazards Assessments (example from Mount Shasta, California)

The record of past eruptions, interpreted from geologic mapping and dating of a volcano's deposits, provides the only practical guide to most likely future hazards and the frequency of their recurrence. Hazard-zonation maps and associated analyses provide an essential basis for design of monitoring networks, long-term eruption forecasts, land-use planning, and short-term emergency plans. During an eruption, real-time monitoring observations are combined with analysis of the volcano's past activity to evaluate the most likely hazards on a day-to-day basis during the course of the eruption.

Hydrological factors can strongly influence the nature of volcanic hazards. Hot volcanic material can rapidly melt large volumes of snow/ice to form debris flows or lahars; post-eruptive debris flows occur when loose volcanic deposits on steep slopes are remobilized by earthquakes or heavy rainfall; groundwater can increase the explosivity of eruptions or the instability of volcanic edifices; eruptions can have long-term effects on erosion and sedimentation around volcanoes. Accordingly, a comprehensive volcanic hazard assessment incorporates information about a volcano's hydrological regime.

Volcano-Crisis Response

Since 1980, the Volcano Hazards Program has responded to more than two dozen volcanic-related emergencies in the United States and other countries. On the basis of demonstrated successful deployments of the USGS/USAID Volcano Disaster Assistance Program (VDAP), the VDAP-style mobile volcano- monitoring system is the explicit mode of response planned for future unrest in the Cascades, Long Valley, parts of Alaska, and elsewhere in the western U.S.

Topical Investigations of Volcanic Processes

USGS volcano-monitoring strategies and interpretations of precursory unrest are founded on an understanding of magmatic processes and eruption dynamics. The Volcano Hazards Program utilizes many tools from seismology, geophysics, geochemistry, field geology, and hydrology to acquire fundamental knowledge about how volcanoes work. The Volcano Hazard Program aims to better integrate topical investigations with monitoring and assessment activities by focusing research at volcanoes with observations and measurements from pre-eruptive and syn-eruptive events. Topical studies include those designed to: discriminate if seismic and other signals are precursors to eruption or signify temporary fitfulness or intrusion without eruption; determine what triggers eruptions and whether a volcanic system is waxing or waning; and identify what factors control the style and explosivity of eruptions.

Furthermore, the diverse character of volcanic eruptions is determined not only by the processes taking place in magmatic systems at depth, but also by near-surface and surficial hydrologic processes before, during, and after eruptions. The Volcano Hazards Program seeks a better understanding of what happens when shallow ground and surface water interact with magma and eruptive products and of the dynamics of lahars and debris avalanches at volcanoes.

Scientific Outreach and Information Dissemination

For information from volcano-hazard studies to be effective, it must be communicated quickly and effectively to reduce volcanic hazards. he Volcano Hazard Program publishes hazard assessments and provides hazards information at diverse public forums and meetings with land-management officials. Before and especially during volcanic crises, program personnel work directly with local officials responsible for public safety. Other outreach includes media briefings on volcanic topics, newspaper articles, and radio and television interviews. Videos, general-interest publications, and short focused fact sheets are produced. Access to data, reports, and photographic materials is available via the Internet, and the program intends to expand its product formats to make greater use of new digital technologies and Internet services.