ANALYSIS OF THE TEMPORAL OCCURRENCE OF SEISMICITY AT DECEPTION ISLAND(ANTARCTICA), A NONLINEAR APPROACH

Deception Island is characterized by small magnitude local events with constant energy flux and very low stress drop. To obtain information about its origin, an interevent time series of 546 events, correspondi ng to an observational period of two month, has been analyzed. From a statistical point of view, data satisfies a Weibull distribution and p resents clustering. A rescaled range analysis reveals that data are no t independent, i.e. have memory, and the correlation dimension saturat es at 2.2; as a consequence, the system can be modeled as a nonlinear iterative equation with three degrees of Freedom that presents chaotic behavior. Taking into account that the average interevent time is of the order of 130 minutes, too short to be only due to tectonic activit y, the above results indicate that some other mechanism may coexist wi th the regional tectonic one. According to several geological and geop hysical observations, we suggest that most of the local events may be originated by pressure waves generated by a sudden change of phase, of sea and Fresh water infiltrated into the main fractures and faults an d also from shallow and confined water-saturated layers.