The nucleation and rupture process of the 1981 Gulf of Corinth earthquakes from deconvolved broad-band data

A R Y Source parameters of the largest three normal faulting earthquakes (Ms6.6, 6.3, 6.4), in the 1981 Gulf of Corinth (Greece) sequence are determined using deconvolved broad-band data (recorded by arrays and single stations) and a 2-D finite source model. Such a model enables the spatial extent, rupture velocity and stress drop of the earthquakes t o be determined and geological observations of surface slip can be included as a further constraint on the waveform modelling. All three earthquakes were shallow (<lo km) with low stress drops (<30 bars), and exhibited source complexity. T h e correspondence between the complexity of the earthquake sources and that of the mapped fault breaks implies that the segmentation of surface faulting in Greece is representative of faulting a t depth. Tiny initial pulses which correlate across the arrays are seen in the seismograms from the Gulf of Corinth earthquakes a t most stations. These initial subevents (<1 per cent of the total moment) are interpreted as the breaking of small asperities which initiated the main rupture and are used to constrain the attenuation correction (t* = 0.2 s).