To influence the decisions made by civil authorities during a volcanic crisis, volcanologists must establish more effective communication with elected officials, news media and local citizens. Creating an effective visualization tool (volcanic hazard maps) is one way to accomplish it, otherwise damaging consequences may follow scientific statements that are not fully understood or believed by civil leaders or the public.Galeras Volcano has three hazard zones around its crater: The high hazard zone, which corresponds to an area where volcanic events of high severity will take place. In this zone there will be no survivors and property will be destroyed. The medium hazard is a transition zone that corresponds to an area that could be affected by the same volcanic phenomena as the high hazard zone, but for larger eruptions. The low hazard zone is the largest area. Although the severity is lowest for people and property in this zone, it should be considered when planning any type of construction.
Using GIS (ERDAS Interpreter for Landsat TM 5 data digital processing), ERDAS Vector for Galeras Volcano Hazard Map displaying and editing, Image drape for 3D visualization (perspective views generating) and IMAGINE VirtualGIS for scene visualization), the entire spectrum of data covering different types of hazards in a given volcanic area could be displayed when needed. Volcanic hazard maps used in addition to remote sensing data and digital elevation models seems to be the best way to help understand the decision makers any volcanic hazardous situation. Remote sensing imagery offers many applications for hazard assessment of volcanic processes, if used with ground-based information. A Landsat TM 5 mosaic was assembled from the two scenes that record the Galeras Volcano influence area. Two color composites were generated, one to help the local people visualize the landscape, and other for geological purposes. The Galeras Volcano hazard map polygons were superimposed to the first color composite, in order to enable querying attributes of image and vector data interactively in 3D.
Every map uses elevation data, symbols and sections to represent a 3D world in two dimensions. From the study area topographic map, a digital elevation model was created by averaging the elevations within the cells of a grid and creating a digital matrix of these elevations. Digital maps offer more choices for relating hazard zones to the landscape. Several types prove especially effective in helping volcanologists communicate with the public. An effective method to improve a non-geologist’s visualization and comprehension of any volcanic hazard map information is to “drape” the different hazard zones as well as remote sensing images over a digital elevation model.
Volcanic hazard maps used with remote sensing data and digital elevation models are proving to be effective in helping people responsible for the public welfare of communities exposed to volcanic risk explain volcanic hazardous situations. They are also being used to develop long-range land use as well as design emergency evacuation routes. The perspective views generated by this rendering in 3D methodology allows the non-geologist to see any volcanic hazard map as a three dimensional representation of a 3D world, where topography and its influence on volcanic hazard is evident.