Source parameters of some large earthquakes in Northern Aegean determined by body waveform inversion


Average source parameters for three large North Aegean events are obtained from body wave inversion for the moment tensor. The parameters for the events are as follows:[Figure not available: see fulltext.] The events exhibit dextral strike-slip faulting with the T axis striking NS and nearly horizontal, implying extension in this direction. The focal mechanisms obtained are in agreement with the seismotectonic regime of the North Aegean. It is known that the region is tectonically controlled by the existence of the strike-slip Anatolian fault and its westward continuation in the Aegean, as well as the NS extension the whole Aegean area undergoes. The components of the moment tensor show that the region is dominated by compression in the EW direction which is encompassed by extension in the NS direction. All the events were found to be shallow (≤10 km) with a source time function of approximately 8 s duration and small stress drop values. The teleseismic long period vertical P-waves exhibited distortions, that could be attributed to lateral inhomogeneities in the source structure or more probably to a nonflat water-crust interface. © 1991 Birkhäuser Verlag.

Publication Title

Pure and Applied Geophysics PAGEOPH