Professor Marcus Bursik
Department of Geology
University at Buffalo
Buffalo, NY 14260


Many types of geophysical flows such as debris flows and pyroclastic flows can
be classified as granular avalanches. While sedimentation from these volcanic
granular flows leaves sometimes spectacular deposits that have been the 
subject of intense study for the past half-century, the effects of erosion 
have been more difficult to ascertain.  Despite the relationship between 
slope angle and thickness of a stable layer of loose debris on a slope, which 
requires erosion during flow events, the positive change in volume of 
volcanic granular flows during transport has not been systematically 
studied.  We present a model that simulates granular avalanches in which 
erosion as well as sedimentation cause significant changes in the mass and 
momentum during flow. We test the model against laboratory experiments and 
volcanological field data.  We are able to obtain a reasonable fit of 
numerical model to both types of data.