Temporal variation of body wave attenuation as related to two earthquake doublets in W. Greece

In this research four earthquakes, which are considered to compose two earthquake doublets, recorded prior to and after a magnitudeM _s =5.0 and a magnitudeM _s =4.8 event in W. Greece are used to derive temporal variations ofP-wave attenuation in the region.Spectral ratios at four stations are computed and the results indicated a variation (increase) ofQ of the order of 15–20%. To confirm that this variation is not an artifact due to changes of the source parameters, a smaller event which occurred at the same hypocentre was used as a Green function and the deconvolution proved that the earthquakes of one of the doublet possessed the same source parameters.The outcome of this research verifies the possible role of the migration of fluids in the crust in the focal region and their effect on the attenuation of seismic waves.