SPATIAL AND TEMPORAL ANALYSIS OF A SEISMIC SERIES USING A NEW VERSIONOF THE 3-POINT METHOD - APPLICATION TO THE 1989 ANTEQUERA (SPAIN) EARTHQUAKES

The three point method (TPM) has been successfully applied to several seismic series and has provided information about the spatial characte ristics (azimuth and dip) of the fault planes activated in the rupture process. A new development of the TPM to determine temporal character istics, is presented, to obtain the evolution of the fracturing proces s of an active fault system. For the analysis of the 158 microearthqua kes and earthquakes that took place in the seismic series of Antequera ih June 1989, the choice of a threshold magnitude (m(u) = 2.5) has pe rmitted the events related to the most relevant fractures to be distin guished. Secondly, only the events between two concentric spheres (her e named Spatial Crown) with respect to a given earthquake, have been u sed in order to avoid taking into account earthquakes that are too clo se to each other, together with the very distant events that have litt le relation to the event analysed. The Spatial Crown has permitted som e clear results in the Antequera series, where we have found that the fracturing process began fundamentally with N 80 degrees E planes and evolved to N 65 degrees W planes. Finally, an error analysis enables a n estimation of the uncertainty in the results to be obtained from the errors in the data.