Remote Sensing Observations for Volcano Monitoring and Hazard Mitigation

Volcanic eruptions are spectacular but dangerous phenomena to study on-site, and they present many challenges because of the diversity of activity and their remote locations. Indeed, the tragic loss of life at Galeras and Mt. Unzen volcanoes in the early 1990s illustrates the dangers associated with studying active volcanoes at close quarters. However, much progress has been made in volcano remote sensing during the last decade, and further substantive developments are expected over the next few years as several countries fly next-generation spacecraft. In particular, NASA’s Terra spacecraft will provide unprecedented capabilities for volcano monitoring, and a team of 20 remote sensing volcanologists have been working for almost a decade to develop algorithms for the routine monitoring of active volcanoes. Aircraft data also provide valuable data sets, and serve as experimental test beds for future spaceborne topographic and thermal infrared mapping systems. Many parts of the spectrum, from UV to microwave wavelengths are now employed to study such phenomena as volcanic ash clouds, the thermal anomalies associated with active lava flows and domes, ground deformation due to intrusions. Topographic mapping has also been conducted from satellites and aircraft in order to detect surface changes due to erosion of pyroclastic flows or the formation of new lava flow fields. This paper reviews many of these methods, drawing upon ERS-2, GOES, Landsat, RADARSAT, SPOT and TOPSAR data collected for volcanoes in Hawaii, the Galapagos Islands and the Philippines. The value of radar remote sensing observations of volcanoes in remote parts of the world (e.g., South America, Central Africa, and Indonesia) will also be described. On-going techniques that permit the near real-time satellite observation of volcanic eruptions will be discussed in order to provide a basis for assisting volcano disaster mitigation.