Optical methods for monitoring of volcanoes: techniques and new perspectives

Present optical techniques. which are considered to be relevant to monitor volcanoes, are reviewed. A short description of each technique is given, as well as the peculiar conditions of applicability. Recent experimental resu lts taken at Solfatara crater with a fiber-coupled diode laser system are r eported and discussed. To take into account the tremendous progress that is experiencing the field of new laser sources and optical materials, an over view to future laser devices, that may have a significant impact in the fie ld of gas monitoring, is given. (C) 2001 Elsevier Science B.V. All rights r eserved.