New USGS Tools to Analyze and Forecast Volcanic Ash Hazards

The U.S. Geological Survey (USGS) has undertaken a focused effort over the past several years to develop scientific tools to better forecast and assess volcanic ash hazards during explosive eruptions.  Here we present two key tools; the 3-D finite volume ash dispersion model Ash3d, and a web-based satellite imagery viewer Volcview.

Ash3d has been in development by the USGS since 2010 for research and for operational use during volcanic crises.  Model inputs include plume height, eruption start time, duration, and erupted grain-size distribution, along with 3-D time-varying meteorology provided by any of several numerical weather prediction models. Ash3d produces forecasts and animations of time-changing cloud height, cloud mass load, and maximum ash concentration in the cloud. For ashfall hazards, Ash3D produces forecast maps of ashfall thickness, the time of arrival, and duration of ashfall.  Output formats include text, gif, kmz, shapefiles for GIS applications, and netcdf, for import into U.S. National Weather Service AWIPS systems.  A user-friendly web-based version using NOAA Global Forecast System meteorology (https://vsc-ash.wr.usgs.gov) is used by the USGS, NOAA, the U.S. Air Force, and more than a dozen volcano observatories in several countries, to forecast ash transport before and during eruptions.  More than two dozen automatic runs are performed daily.  Results are posted at sites such as the Alaska Volcano Observatory’s page for volcanoes at unrest (http://www.avo.alaska.edu/). 

Volcview (http://avo-volcview.wr.usgs.gov/) is a public web-based tool to view and analyze satellite images for volcanic ash in the North Pacific Region.  The tool displays mid-IR, thermal-IR, brightness-temperature-difference, and visible-wavelength images from AVHRR, GOES, and MODIS satellite platforms, for images retrieved within the past week or so.  These images can be overlain with maps of coastlines, volcanoes, communities, volcanic-ash-advisory polygons, and NOAA alert regions.  The interface allows polygons to be drawn around suspected clouds.  It can also display temperature-altitude profiles (derived from Global Forecast System meteorology) at chosen locations, to help determine cloud height from cloud brightness temperature.  For chosen locations, Volcview can also display a family wind trajectories at different altitudes, moving forward or backward in time, to help users anticipate cloud movement, and determine the source volcano.  Images can be saved and shared.  Volcview is used regularly at the Alaska Volcano Observatory to detect and evaluate the height, extent, and trajectory of possible ash clouds.

These tools, along with several others under development at the USGS, are helping to make ash-hazard assessments both more rapid and quantitative.