THE NUCLEATION AND RUPTURE PROCESS OF THE 1981 GULF OF CORINTH EARTHQUAKES FROM DECONVOLVED BROAD-BAND DATA

Source parameters of the largest three normal faulting earthquakes (M( s)6.6, 6.3, 6.4), in the 1981 Gulf of Corinth (Greece) sequence are de termined using deconvolved broad-band data (recorded by arrays and sin gle stations) and a 2-D finite source model. Such a model enables the spatial extent, rupture velocity and stress drop of the earthquakes to be determined and geological observations of surface slip can be incl uded as a further constraint on the waveform modelling. All three eart hquakes were shallow (<10 km) with low stress drops (<30 bars), and ex hibited source complexity. The correspondence between the complexity o f the earthquake sources and that of the mapped fault breaks implies t hat the segmentation of surface faulting in Greece is representative o f faulting at depth. Tiny initial pulses which correlate across the ar rays are seen in the seismograms from the Gulf of Corinth earthquakes at most stations. These initial subevents (<1 per cent of the total mo ment) are interpreted as the breaking of small asperities which initia ted the main rupture and are used to constrain the attenuation correct ion (t() = 0.2 s).