Remote sensing of volcanoes

Abstract

Volcanoes are amongst the few geological landforms which undergo changes at scales and rates sufficient to warrant frequent surveillance. Monitoring of volcanoes is important for documenting their course of activity in order to understand their behavior. Monitoring is therefore an essential precursor step before the goals of predicting eruptions and their related hazards can be achieved. Modern remote sensing techniques provide the only means whereby any volcano in the world can be studied. In many cases, remote sensing observations provide the only available data on the activity of an individual volcano; in other cases they may support and refine field observations. Here I report the results of studies by my colleagues and I on the applications of the Landsat Thematic Mapper (TM) and other satellite systems to the identification and monitoring of active volcanoes. Three different applications will be briefly discussed: (1) identifying active volcanoes; (2) spectral studies; and (3) thermal monitoring of volcanoes. The Landsat Thematic Mapper is in sun-synchronous orbit around the Earth at an altitude of 705 km, such that it passes overhead any given volcano once every 16 days. It is equipped with seven sensors, four operating in the visible and near infrared (0.45–0.90 μm); two in the short wavelength infrared (1.55–1.75 and 2.08–2.35 μm) and one in the thermal infrared (10.4–12.8 μm). It images a swath 185 km wide with a pixel size of 30 m (120 m in the thermal infrared band). The French SPOT system images a 65 km wide swath with a pixel size of 20 m in each of four multispectral bands (visible and near infrared) but also offers panchromatic data with a pixel size of 10 m, and the ability to provide stereoscopic views.