Effects of the seismic attenuation pattern at the bend of the Southeastern Carpathians on the peak ground motions from local crustal earthquakes

The effects of the seismic attenuation pattern observed at the bend of the Southeastern Carpathians on the peak ground motions (PGMs) produced by local crustal earthquakes are analyzed using theoretical experiments. The synthetic seismograms – ground velocity time histories, vertical component – are calculated by the multimodal summation method in layered inelastic media. The theoretical waveforms evidence that the lateral variations of the attenuation structure may result in higher peak amplitudes at larger epicentral distances, in other words, the wave attenuation may dominate the wave spreading in the study area, within epicentral distances up to a few tens of km. The result is in good agreement with the observations, and emphasize the substantial contribution of the crustal attenuation to the pattern of ground motions caused by crustal, as well as intermediate-depth earthquakes of Vrancea.