Time-series analysis of effusive volcanic activity using the ERS along track scanning radiometer: The 1995 eruption of Fernandina volcano, Galápagos Islands

Abstract

The ERS-1 Along Track Scanning Radiometer (ATSR) provides frequent shortwave and longwave infrared radiance data of every terrestrial volcanic region, at a spatial resolution of 1 km 2. By adopting a simplified model that assumes that any observed active lava flow is composed of two distinct thermal components, we present techniques that allow subpixel lava flow areas to be estimated from the ATSR spectral radiance data. Such estimates are especially useful in documenting effusive volcanic activity occurring in remote regions, where ground observations may be sparse or completely lacking. We use a time-series ATSR dataset to document the 1995 eruption of Fernandina Volcano, an important but isolated volcanic island in the Galápagos archipelago. We estimate that in 1995 Fernandina produced a 6 km 2 lava flow field with a volume of around 20 million m 3, a similar magnitude to previously studied Fernandina eruptions. This is the first time-series analysis of an active Galápagos lava flow produced using remotely sensed data. Previous Fernandina flows have been investigated many months or years after the activity had ceased. The current and future availability of frequent, low-spatial resolution infra-red radiance data from spaceborne sensors such as the Advanced Along Track Scanning Radiometer (AATSR) and the Moderate Resolution Imaging Spectrometer (MODIS) should ensure that adaptations of these techniques can be used to document future volcanic eruptions occuring in similarly isolated regions.