| Lahars are large debris flows that originate on volcano flanks and can surge tens or even hundreds of kilometers downstream from a volcano. Volcanologists help mitigate volcanic hazards by creating hazard-zonation maps that depict estimates of the location and extent of areas inundated by future lahars and other volcanic processes. Taking a new approach to the problem of estimating the extent of lahar inundation, Iverson and others (1998) used the results of scaling and statistical analyses of the geometry of 27 lahar paths at nine volcanoes to develop equations that predict inundated valley cross-sectional and planimetric areas as functions of lahar volume. LAHARZ, menu-driven software that runs within a Geographic Information System (GIS), uses these equations, a Digital Elevation Model (DEM) and user-specified lahar volumes to provide an automated method to map areas of potential lahar inundation. For user-selected drainages and user-specified lahar volumes, LAHARZ can delineate a set of nested lahar-inundation zones that depict gradations in hazard in a manner that is rapid, objective, and reproducible. -- Schilling, 1998 |
