DETECTION OF A VOLCANIC FRACTURE OPENING IN JAPAN USING GLOBAL POSITIONING SYSTEM MEASUREMENTS

THE Global Positioning System (GPS) is a powerful tool for detecting crustal deformation1; for example, the technique has been used to detect plate boundary movements in California2. Here we report observations of crustal deformation associated with seismic swarm and sea-floor volcanic activity off the east coast of the Izu Peninsula, Japan, in July 1989, using a fixed-point GPS network. These measurements have enabled us to capture some rarely observed features of seismic and volcanic activity. We have, for the first time, used GPS fixed-point measurements to follow the evolution with time of the crustal movements; such measurements provide a continuous uninterrupted record of deformation. Our observations were supported by independent data from other sources, thus providing further evidence for the utility of the GPS. © 1990 Nature Publishing Group.