Sixth National Earthquake Engineering Conference, İstanbul, Türkiye, 16 - 20 Ekim 2007, ss.1-11
We determined the seismic model of the soil column within a residential project site in
Istanbul, Turkey. Specifically, we conducted refraction seismic survey at 20 locations using a
receiver spread with 48 4.5-Hz vertical geophones at 2-m intervals. We applied nonlinear
tomography to first-arrival times to estimate the P-wave velocity-depth profiles and performed
Rayleigh-wave inversion to estimate the S-wave velocity-depth profiles down to a depth of 30
m at each of the locations. We then combined the seismic velocities with the geotechnical
borehole information regarding the lithology of the soil column and determined the sitespecific
geotechnical earthquake engineering parameters for the site. Specifically, we
computed the maximum soil amplification ratio, natural period of the soil column, maximum
surface-bedrock acceleration ratio, depth interval of significant acceleration, spectral
acceleration ratio, and design spectrum periods TA-TB. We conducted reflection seismic survey
along five line traverses with lengths between 150-300 m and delineated landslide failure
surfaces within the site. We recorded shot gathers at 2-m intervals along each of the the
seismic line traverses using a receiver spread with 48 40-Hz vertical geophones at 2-m
intervals. We applied nonlinear tomography to first-arrival times to estimate a P-wave
velocity-depth model and analyzed the reflected waves to obtain a seismic image of the deep
near-surface along each of the line traverses.