Site Response Characteristics of Marine Deposits of Eastern Coast of Cyprus

When an earthquake occurs, the site destruction is substantially affected by the soil response. For a long period, spectral acceleration and seismic resistant structures of the site has been employed for designing. The response of the site is computed as the spectra response of a specific site, in seismic response analysis. The parameters which are required for the seismic response analysis are the distance of the soil surface to bedrock, soil geotechnical properties, soil profile and its thickness, and shear wave velocity. The analysis of ground response is needed to estimate the movement of the ground surface for improvement of the design response spectrum and to assess the strain and dynamic stresses for appraisal of liquefaction potential. It is also required to distinguish forces from the earthquake which may lead to structures instability. A perfect evaluation of the ground response would also provide the mechanism of the rupture at an earthquake source, the growth of the stress waves which move through the earth up the bedrock beneath a given site, to distinguish how soil over the bedrock affects the movement of the ground surface. As a result, ground response analysis can be defined as how soil deposit responds to the movement of the rock beneath it. Therefore, soil properties are of utmost importance in this regard, as they determine the ground motions and movement especially in cases where soils are soft or loose. For this reason, the identification of the changes in period and acceleration parameters of the ground motion is very important. In this study, shear wave velocity is obtained indirectly from CPT data of Tuzla area. For seismic response analysis all around the world, the ideal depth for soil profile and data is the upper 30 m of the ground which is considered for the area under study. Seismic waves can be intensified or weakened by the condition of the subsurface soil. Therefore, for the investigation of seismic response, determination of the soil characteristics and shear wave variation associated with soil property variations is essential. In this study, the soil properties and liquefaction behavior were assessed using NovoCPT and LiqIT softwares respectively for Richter magnitudes of 6.0, 6.5, and 7.0, and the ground response was estimated using DeepSoil and SeismoSignal softwares. The analysis of the CPT data showed that there is no major risk for the liquefaction at the entire total depth as also justified by the empirical procedures apart from the 7 Richter magnitude earthquake. In fine-grained soils of Tuzla, however earthquakes (Mw ≥ 6.5) might cause induced ground deformations, ground settlements and lateral spreads, which could not be evaluated with the available CPT based methods. The response displacement, velocity and acceleration of the first layer and bedrock revealed that approximately during the first period when the amplitudes of ground motion are high based on high energy absorption in depth and soil characteristics, the acceleration, velocity and displacement are high. Whereas, when the amplitude decreases (during the second period) the absorbed energy is released and these parameters also dramatically decrease and reverse action will occur for the first layer, which was observed for all CPT locations. It was concluded that the amounts of response displacement, velocity and acceleration for all bedrock locations are nearly the same, whereas a varying trend can be observed for the response of first layers, which is directly related to soil characteristics in the region.