Ground motion amplitude is increased or decreased due to propagation through basin structures and near-surface layers. This effect, known as site amplification, can cause variability of earthquake ground motion over short distances. A major worldwide problem is to characterize site-conditions.
The aim of this proposal is two-fold:
- the characterization and classification of site conditions in Greece using geology and geophysics and
- the simulation of strong ground motions from earthquake scenarios in selected urban regions taking into account the site-effect.
The workflow is organized into nine WP's. In order to characterize site conditions (first target) the shallow (up to 30m) shear-wave velocity, Vs30 will be used as a proxy to classify site conditions, because it serves as an indicator of ground-motion amplification, and is related to physical material properties.
The data will come from two sources:
- from previously collected geologic and geotechnical data, which will be organized in a single database and
- from field measurements at selected sites with known geology, where we will apply Seismic Cone Penetration Test (SCPT).
The site classification of rock and soil units will confront with the site categories of Eurocode 8 (EC-8) and NEHRP (2000) directives. The validation of our results will be performed at the sites of strong motion (accelerographs) stations in Greece, operated by one of the partners, using the abundant available records from many earthquakes. The application to earthquake scenarios (second target of this project) will be done in three cities, which are selected based on their topography and geology (Edessa), historical seismicity (Xanthi) and recent strong seismicity (Grevena). This study will enhance our understanding of the correlation between site conditions and site response. Identification of areas susceptible to ground-motion amplification would improve seismic hazard evaluation and mitigation efforts.