Acoustic emission at the Stromboli volcano: scaling laws and seismic activity

We analyze acoustic emission data taken over several years at the Stromboli volcano on the Aolean Islands in Italy. The data consist of single acousti c events which are organized in clusters, called paroxysmal phases. each co mposed of up to millions of events. The distribution of amplitudes and temp oral intervals were measured for both the elementary events and the cluster s: common power laws were found, raising the question ora single underlying mechanism with a self-similar hierarchical structure ranging in time from seconds to months. Such scaling laws are interpreted based on the paradigm of self-organized criticality. Finally, we hint at a close temporal correla tion between ultrasonic and volcanic activity. (C) 2000 Elsevier Science B. V. All rights reserved.