HR: 14:00h
AN: U43C-02 INVITED     [Abstracts]
TI: Communicating Uncertainty to the Public During Volcanic Unrest and Eruption -A Case Study From the 2004-2005 Eruption of Mount St. Helens, USA
AU: * Gardner, C A
EM: cgardner@usgs.gov
AF: U.S. Geological Survey, Cascades Volcano Observatory, 1300 SE Cardinal Court Suite 100, Vancouver, WA 98683 United States
AU: Pallister, J S
EM: jpallist@usgs.gov
AF: U.S. Geological Survey, Cascades Volcano Observatory, 1300 SE Cardinal Court Suite 100, Vancouver, WA 98683 United States
AB: The earthquake swarm beneath Mount St. Helens that began on 23 September 2004 did not initially appear different from previous swarms (none of which culminated in an eruption) that had occurred beneath the volcano since the end of the 1980-1986 eruptions. Three days into the swarm, however, a burst of larger-magnitude earthquakes indicated that this swarm was indeed different and prompted the U.S. Geological Survey's Cascades Volcano Observatory (CVO) to issue a change in alert level, the first time such a change had been issued in the Cascades in over 18 years. From then on, the unrest accelerated quickly as did the need to communicate the developing conditions to the public and public officials, often in the spotlight of intense media attention. Within three weeks of the onset of unrest, magma reached the surface. Since mid-October 2004, lava has been extruding through a glacier within the crater of Mount St. Helens, forming a 60 Mm³ dome by August 2005. The rapid onset of the eruption required a rapid ramping up of communication within and among the scientific, emergency-response and land-management communities, as well as the reestablishment of protocols that had not been rigorously tested for 18 years. Early on, daily meetings of scientists from CVO and the University of Washington's Pacific Northwest Seismograph Network were established to discuss incoming monitoring data and to develop a consensus on the likely course of activity, hazard potential and the uncertainty inherent in these forecasts. Subgroups developed scenario maps to describe the range of activity likely under different eruptive behaviors and sizes, and assessed short- and long-term probabilities of eruption, explosivity and hazardous events by employing a probability-tree methodology. Resultant consensual information has been communicated to a variety of groups using established alert levels for ground-based and aviation communities, daily updates and media briefings, postings on the worldwide web, teleconferences, and meetings with land and emergency managers. Initial concerns revolved around the questions of if and when an eruption would occur, whether it would be explosive, and how large-all questions without definitive answers. As the eruption progresses, concerns have transformed to whether the eruptive behavior will change and how long the eruption will last-also questions lacking definitive answers. We have found it important in communicating our uncertainty to the public to articulate how we came to our conclusions and why our answers cannot be more definitive. We have also found that framing volcanic uncertainty in terms of more common analogies (e.g. knowing that conditions are right for development of a tornado, but not being able to predict exactly when a funnel cloud will form, precisely where it will touch down, or how severe the damage will be) appears to help the public and public officials understand volcanic uncertainty better. As the eruption continues and people become more accustomed to the activity, we find an increasingly more knowledgeable public who can better understand and deal with uncertainty. Also, it is clear that establishing interagency relationships by developing volcano response plans before a crisis greatly facilitates a successful response. A critical component of this planning is discussing uncertainties inherent during volcanic crises such that when unrest begins, the concept of, and reasons behind uncertainty are already well understood.
DE: 8488 Volcanic hazards and risks
SC: Union [U]
MN: Fall Meeting 2005