Volcanic activity, both past and present, is subject to constant study and analysis in the search for improved land-use planning, the scope of which is to help minimise hazard in risk areas.

Authorities often need data over volcanic areas, not only to monitoring eruptions, but also to produce maps and thematic diagrams predicting the potential risk to the surrounding area.

In this field, remote sensing data is used to detect lithological differences, vegetation changes, altimetric variations after volcanic events, and the extent and growth of urban areas into endangered areas.

In addition, satellite data can provide an overview of large volcanic areas in a single frame, making it possible to create image maps of areas as large as 180 x 180 km, with an accuracy comparable to 1:100000 map scale from a single LANDSAT 5 & 7 TM pass over the area. A higher resolution can be achieved by taking data acquired by other satellites (KVR, SPOT, IRS, etc.) and merging these high resolution images with LANDSAT or other multispectral sources.

The study of volcanic areas is mainly done from optical data, so that the same ground target can be examined in different spectral bands (usually ranging from visible to far infrared).

Radar missions like the European Space Agency's ENVISAT & ERS-2 satellites, make a unique contribution when the need is for altimetric change detection, or when volcanic eruptions cause other phenomena that can be monitored by radar sensors (lava flow, ground fissures, earthquakes, mud slides, floods, etc.).

The following pages show photos, ground information and satellite images to help in the interpretation of the remote sensing data; all of which make possible the analysis of features not detectable on photographs.