The topics included in this issue deal with many aspects of volcanic and seismic activity, two of the natural hazards of geological origin that have the greatest impact and pose the predominant risk to society. This book comprises eighteen papers, most of which were presented at an international seminar organized and held at the Complutense University of Madrid in October 2001. The papers address geodetic, geophysical and geochemical effects caused by seismic and volcanic activity; monitoring of volcanic and seismic processes using space and terrestrial techniques; complementarity of these...