Mount St. Helens erupted with previously unseen power on the morning of May 18, 1980. A lethal lateral blast of hot gas, steam, and rock debris stormed across the landscape at speeds up to 1,100 kilometers per hour. Temperatures within the blast climbed to more than 300 degrees Celsius. Snow and ice on the volcano melted, forming fast-moving streams of water and rock debris that rushed down the river valleys. A large ash plume was pushed 19 kilometers into the sky and dropped an estimated 490 tons of ash across 57,000 square kilometers of the western United States. The majority of the damage occurred immediately following the eruption, and the blast zone was devoid of vegetation. A series of eruptions associated with this event finally ended in 1986 after more than a dozen lava extrusions built a dome in the crater.

During the summer of 1982, Lisa M.B. Harrington was a United States Department of Agriculture (USDA) Forest Service volunteer at Gifford Pinchot National Forest. Throughout the summer she photographed the volcano and surrounding areas. In 1984 she returned to selected sites and has been doing ground-based repeat photography ever since. She and fellow geographer John Harrington now photograph Mount St. Helens annually. Her photographs were the foundation of this vegetation recovery research and led to the application of remote sensing and GIS technology. (See main article, "Mount St. Helens Recovery Followed With GIS.")

"In the human lifespan, catastrophic volcanic disturbances of this sort are relatively rare events," states Luke Marzen. "When these disturbances occur, the equilibrium state of an ecosystem is often disrupted. GIS and remote sensing provide a means to observe disturbed ecosystems over time and investigate important factors for recovery of these landscapes."

"There is a great deal of value in using GIS and remote sensing technology," continues Marzen. "In addition to the dimension of studying the landscape over time from above, GIS and remote sensing studies can be applied to other areas that have not had historic ground data collection and analysis. For example, several Mexican volcanoes have erupted and have not had any long-term ecological studies. With remotely sensed satellite imagery, image processing tools, and GIS software, we can study these and most other locations, even private and inaccessible lands."

Marzen would like to see additional research attempted in areas of other volcanic disturbances. The methods developed in his landscape scale studies at Mount St. Helens offer the ability and opportunity to investigate other volcanic disturbances throughout the world such as El Chichon in Mexico and Mount Pinatubo in the Philippines.

Marzen's Mount St. Helens research can also be related to other natural and/or human-induced disturbances. The results of his methodology are quantitative values that represent change. These values can be used in environmental models that can be related to other factors to attempt to explain the variations in the landscape. For example, land resource managers of all kinds, including public land stewards such as forest managers and private landowners, may be interested in how to manage the recovery of an ecosystem. "Our research methodology could relate to fire, landslide and, of course, volcanic vegetation recovery," adds Marzen.

For more information about spatial solutions, call Leica Geosystems GIS & Mapping (tel.: [toll-free within the U.S.] 1-877-463-7327 or [outside the U.S.] 1-404-248-9000; Web: gis.leica-geosystems.com). For more information on Mount St. Helens, visit Mount St. Helens National Volcanic Monument at www.fs.fed.us/gpnf/mshnvm and www.fs.fed.us/gpnf/mshnvm/20th-anniversary, the Gifford Pinchot National Forest at www.fs.fed.us/gpnf and Weyerhaeuser's Forest Learning Center at www.weyerhaeuser.com/citizenship/publicoutreach/ sthelens/default.asp.

See also "Mount St. Helens Recovery Followed With GIS."