Volcanoes can have extremely wide ranging effects. Even a single eruption can cause disastrous climate changes at great distance from the source. Thus, it is important to have a system to monitor even the most remote volcanoes. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on the Terra spacecraft and other satellite sensors provide imagery that is critical to the global volcano monitoring solution.
Satellites can provide essential data on volcanoes, tracking many characteristics including gaseous emissions, surface temperatures, and rates of magma extrusion. Changes in these characteristics provide insight into subsurface magma movements. ASTER records data in 14 spectral bands at wavelengths ranging from 0.52 micrometers to 11.65 micrometers in the visible and near infrared, shortwave infrared, and thermal infrared regions. Each scene covers an area of approximately 3,600 square kilometers (60 X 60 km) at relatively high resolution (15 meters, 30 m, and 90 m in visible and near infrared, shortwave infrared and thermal infrared, respectively).
Temperature thresholds set by the Alaska Volcano Observatory for specific volcanoes are used in combination with other factors to track the significance of temperature deviations spotted by the satellite. Such ‘thermal anomalies’ detected with the Advanced Very High Resolution Radiometer and Moderate Resolution Imaging Spectroradiometer trigger tasking requests for higher resolution observations by ASTER. To enable this more detailed monitoring, the Alaska Volcano Observatory logs such data requests and transmits them to the National Aeronautics and Space Administration’s (NASA) Land Processes Distributed Active Archive Center in South Dakota. This group works with the ASTER team at the Jet Propulsion Laboratory in California to schedule expedited observations. ASTER Ground Data System staff in Japan then enable the uplink of the observation schedule to the spacecraft.
The images are prepared by NASA’s Land Processes Distributed Active Archive Center and distributed via a custom web interface designed to expedite rapid assessment and retrieval of these emergency datasets. ASTER data are analyzed by staff at the Alaska Volcano Observatory and integrated with other available satellite imagery and ground-based data, such as seismic activity reports, to determine the current state of the volcano. If necessary, a status report is issued to Federal, state, and local agencies.
The accompanying poster presents the process in action by highlighting observations of the Augustine Volcano in Alaska during early 2006. ASTER’s thermal infrared data provided information on surface temperature conditions, which were used to map pyroclastic flows as well as ash and gas plumes. Composite images using ASTER data, digital elevation models, and Landsat 7 imagery provided useful representations of temperature conditions, plume extent, and cloud-top topography. Regularly updated reports on Augustine’s status provided timely information to interested organizations.
These systems have also promptly provided data on other volcanoes in the North Pacific on many occasions, improving the accuracy of regional status assessments.
Archived ASTER data may be obtained from the Land Processes Distributed Active Archive Center (http://LPDAAC.usgs.gov) or from the ASTER Ground Data System (http://imsweb.aster.ersdac.or.jp/).
By Kenneth A. Duda1, Rick Wessels2, Michael Ramsey3, Jonathan Dehn4
1 – SAIC, contractor to U.S. Geological Survey (USGS) Center for Earth Resources Observation and Science, Sioux Falls, SD. Work performed under NASA grant number NNG04GO69G and USGS contract 03CRCN0001. Email: duda@usgs.gov
2 – U.S. Geological Survey, Alaska Volcano Observatory
3 – University of Pittsburgh and ASTER Science Team
4 – University of Alaska Fairbanks