No abstract

No abstract

No abstract

Abstract:To estimate the seismic response according to Eurocode (EC8) and almost all other national codes, site conditions have to be properly characterized so that soil amplification and the corresponding peak ground motion can be calculated. In this work, different geophysical and geotechnical methods are combined in order to define the detailed ground conditions in selected sites of the Hellenic Accelerometric Network (HAN) in Crete. For this purpose, the geological information of the sites and shear wave velocity, calculated from surface wave measurements, is used. Additionally, ground acceleration data recorded through HAN have been utilized from intermediate depth earthquakes in the broader area of South Aegean Sea.Using the recorded ground motion data and the procedure defined in EC8, the corresponding elastic response spectrum is calculated for the selected sites. The resulting information is compared to the values defined in the corresponding EC8 spectrum for the seismic zone that includes the island of Crete.The comparison shows that accurate definition of ground type through geological, geotechnical and geophysical investigations is important. However, our current comparison focuses on the distribution of values rather than the absolute values of EC8-prescribed spectra, and the results should be considered in this context.

The geo-characterization of site conditions is crucial for the estimation of regional elastic  spectra.  The  work  to  be  done  in  the  framework  of  the  “GEO-CHARACTERIZATION”  THALIS-project,  will  combine  geotechnical  and geophysical methods and evaluate them to estimate critical geotechnical parameters. Although  geotechnical  tests  in  lab  may  provide  more  accurate  estimates  of geotechnical  parameters,  they  require  costly  and  time  consuming  drilling procedures.  On  the  other  hand  geophysical  methods  are  useful  in  providing estimates in situ of subsurface physical properties, which are not directly related to geotechnical parameters. Within “GEO-CHARACTERIZATION” THALIS-project a pilot  survey  for  geotechnical  characterization  at  selected  sites  of  Hellenic Accelerometric  Network in  Crete  will  be  conducted  by  employing  geotechnical, geological  and  geophysical  techniques.  Subsequently,  by  correlating  “geo-data” collected within this project, relations of certain mechanical parameters obtained in laboratory  or/and  in  situ  with  geophysical  parameters  for  typical  geologic formations  and  soils  will  be  established.  The  “GEO-CHARACTERIZATION” project, will focus on the influence of dynamic loads on geotechnical phenomena related to the static stress field variation, the estimation of site effects due to seismic motion and the proposal of regional elastic spectra for seismic provisions as well as their comparison with the  corresponding elastic design spectra of  Eurocode 8 (EC8).