2D Structure

Based on the extensive seismic - geophysical campaign and the detailed geotechnical in-situ survey and laboratory testing it was possible to determine the main geologic formations in Mygdonia basin, the soil stratification and dynamic properties. The results of all these measurements were correlated and compared to each other. Shear wave velocity, VS, values evaluated with different methods and properly correlated were used, with other parameters, to construct detailed and accurate 1D and 2D profiles for seismic ground response analysis.

The resulting 2D soil model in the center of the valley is presented in Figure 1 and consists of 7 soil layers that can be grouped in two units based on their geological age. Surface layers A, B, C and D are belonging to the Mygdonia sedimentary system and have an average Vs of 330 m/s, while layers E, F and G∗ belong to the Premygdonian system with average Vs of 750 m/s. Soil layer A is very soft with a mean VS velocity of 130 m/sec. This model consisted the base for the subsequent extent of EUROSEISTEST related research toward the determination of the 3D structure of the basin.


Figure 1: 2D N-S (Profitis - Stivos) soil model (Raptakis et al., 2000). Line F1 coincides with the seismogenic fault of the 1978, M6.5 earthquake.

Suggested Related Publication:
Raptakis, D., F. J. Chavez-Garcia, K. Makra and K. Pitilakis (2000). Site effects at Euroseistest - I. Determination of the valley structure and confrontation of observations with 1D analysis, Soil Dynamics and Earthquake Engineering 19(1), 1-22.