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Inside this Issue |
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| Expanding Technology Aids Volcano Early Warning and Detection Activities | ||
Dr. John Bailey,
Geopysical Institute, Earth and Planetary Remote Systems, UAF |
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Story by Lorien Nettleton
Volcanic activity in Alaska creates more than mere fireworks. Ash spewed into the atmosphere by magma pushing through the Earth’s crust poses a danger to jet aircraft, whose engines can shut down if sufficient ash is ingested. For the safety of the transportation and cargo industries, it is essential that the Federal Aviation Administration (FAA) be able to provide current information about safe routes. The Alaska Volcano Observatory (AVO), a joint program of the United States Geological Survey (USGS), the Geophysical Institute of the University of Alaska Fairbanks (UAFGI) and the State of Alaska Division of Geological and Geophysical Surveys (ADGGS), prepares such information. The years 2005 and 2006 have been the busiest seasons the AVO has seen in the last decade. This meant interesting work for ARSC postdoctoral fellow Peter Webley, who began his research in the Earth Planetary and Remote Sensing (EPRS) group’s volcanology department in January 2006. Three days later, Mt. Augustine, a stratovolcano in Cook Inlet, started spewing ash into the sky, grounding Anchorage air traffic for a day and putting local populations on alert for destructive ash accumulations. Webley immediately went to work running predictive models of Mt. Augustine’s ash cloud dispersal using the Puff Volcanic Ash Tracking Model. Predictive modeling is one aspect of the AVO’s four-part mission to collect satellite data of volcanic activity, process it for clarification, project future patterns of volcanic activity, and issue advisories to the National Weather Service and the FAA. Webley joined colleague and fellow ARSC post doctorate researcher John Bailey, whose detection and analysis activities began in the fall of 2005. The two continue to work under the direction of Ken Dean, director of EPRS and leader of the satellite monitoring group for AVO-Fairbanks. The View from Space As seismic activity is often the first indication of impending eruption, more than 20 volcanoes with a potential impact on population centers or aviation are monitored with a selection of instruments installed directly on the volcano. Data monitoring instruments such as seismometers, electronic distance meters and tiltmeters, provide the most accurate indication of seismic events. Without the ability to monitor physical processes on all 150 potentially active volcanoes in Alaska, the AVO employs space-based monitoring of seismic deformations. Utilizing a combination of rapidly developing remote-sensing satellites and imaging systems technology, researchers at the AVO’s monitoring project are able to direct powerful tools towards detection of a comprehensive range of potential hazards. When Ken Dean began working on the volcano monitoring project in early 1989, a patchwork of rudimentary data collection and transmission tools made it impossible to provide results to decision makers in less than eight hours. Analysis of satellite data required a six-hour drive to the Gilmore Creek Tracking Station, followed by a lengthy analysis process before the results could be faxed to the AVO office in Anchorage. In the mid-nineties, Dean learned that the University of Miami received a NOAA feed from Gilmore Creek Tracking Station and made arrangements to collect the same information via a 10,000-mile detour, thereby trimming the eight-hour delay down to one hour. When the Geophysical Institute acquired an Advanced Very High Resolution Radiometer (AVHRR) in 1993, they began receiving immediate access to data from polar orbiting satellites, relaying five spectral bands of 1 km spatial resolution. The 2001 addition of Moderate Resolution Imaging Spectroradiometer (MODIS) satellites allows 36 spectral channels of data to be relayed to analysts, giving higher definition to features such as thermal anomalies that the AVO researchers are interested in isolating. Two satellites make passes less frequently and data is only available a few times a day for each volcano. With this array of data and communications, data can reach the AVO office in 20 minutes from the time of signal capture. The third satellite data source is a NOAA-operated Geostationary Operational Environmental Satellite (GOES). GOES relays visible spectral information every 15 minutes, and thermal spectral data every 30 minutes, providing ample real-time data, but as the satellite is centered on the equator, the angle of acquisition creates a partial distortion of 4 by 8 km per pixel. This combination of image data sources provides a good monitoring package to study thermal anomalies (or hotspots), which can be precursors to explosive eruption of ash. It also allows for tracking of plumes by detecting the temperature of the plume and comparing it to the temperature of the atmosphere to provide cloud height and location. To continue the development of emergent technologies and accelerate the detection and warning process, Bailey is developing new methods of detecting and analyzing the AVHRR, MODIS and GOES feeds. Every volcano has a unique pattern of activity and non-activity, so knowing that there is a hotspot or ash column rising from the volcano provides information about the historical behavior of that volcano. To better judge the significance of thermal anomalies, Bailey has planned an upgrade to the current analysis process by implementing an algorithm capable of detecting patterns of activity to scan the 18-year EPRS satellite imagery archive and isolating activity patterns. Bailey expects to further automate the hotspot and ash-plume detection process by comparing incoming information to historical data on each volcano, allowing the AVO to more accurately determine the eruption styles of different volcanoes. Predicting the Impact In conjunction with hotspot and ash cloud detection, modeling the ash clouds is at the core of assessing potential impact on human activity from volcanoes. Peter Webley is driving the Puff Model to predict plume behavior and is looking for ways to make the data more widely accessible to the non-academic user. Puff is a volcanic ash tracking model that simulates the dispersion of volcanic ash from an eruption. For emergency-response applications, it requires near real-time forecast wind data to predict the movement of the ash cloud. The model is based on the three-dimensional Lagrangian random-walk formulation of pollutant dispersion. Puff initializes a collection of discrete ash particles representing a sample of the eruption cloud and calculates transport, turbulent dispersion and fallout for each particle. By using Puff to simulate ash cloud particulate trajectories during eruption, researchers are able to visualize the direction and height of the particulate matter. The output is projected on a map of an area of interest surrounding the volcano and overlaid with the graphical depiction of the ash dispersion. The output is currently a two-dimensional visualization, with colored dots representing the direction and differing elevations of particulates. As a model of simple design, Puff is optimized for fast simulation output. The model can execute multiple simultaneous eruptions in minutes, giving predicted plume height and scatter behavior in an operational context. To capitalize on this speedy return on input data, Webley plans to begin ingesting a much higher resolution dataset into the model—from 40 to 8 km for initializing the winds—allowing the researchers to see topographic effects of low level ash fallout down the line. Webley and Bailey are investigating potential for upgrading Puff to run high-resolution simulations with 3D visualization capacity. To add further functionality, the team is looking at creating a code for use with virtual globe browsers such as Google Earth or EarthSLOT that would run live data and could be added to any interested party’s selection of information layers within the 3D browsing application. Given the wide community of virtual globe developers, everything from air-traffic routes to local weather patterns are available as a dataset to layer over the topographic imagery. Making ash-plume information available will add another resource for anyone interested in tracking potential ash-plume related hazards. For more information, visit: Alaska Volcano Observatory, Puff Volcanic Ash Tracking Model |
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| Challenges Index | ||
