Browsing by Author "Kramer, Steven L."

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Empirical Correlations of Shear Wave Velocity (Vs) and Penetration Resistance (spt-N) for Different Soils in an Earthquake-Prone Area (erbaa-Turkey)
(Elsevier, 2011) Akin, Muge K.; Kramer, Steven L.; Topal, Tamer
The seismicity of the northern part of Turkey is mainly controlled by the North Anatolian Fault zone (NAFZ). The NAFZ is one of the world's most active seismic zones, and has produced destructive earthquakes and related hazards in the northern region of Turkey. Several earthquakes and earthquake-related hazards have occurred along different segments of this fault zone in the recent past. The study area, Erbaa town, is located along the eastern segment of North Anatolian Fault Zone (NAFZ) and is one of the largest towns of Tokat Province in the Middle Black Sea Region of Turkey. The center of Erbaa is located on the left embankment of the Kelkit River. After the disastrous 1942 (M-s=7.2) and 1943 (M-s=7.6) earthquakes, the settlement was shifted southwards. As a part of a seismic microzonation study of the Erbaa area, shear wave velocity (V-s) values of the geological units exposed in this area were required for site response analyses. The geological units in the study area consist mainly of alluvial and Pliocene units. These layers were evaluated on the basis of drilling, in-situ (SPT, SCPTU and SPT-based uphole) and laboratory testing. In this study, empirical correlations between shear wave velocity (V-s) and standard penetration test blow counts (SPT-N) were considered in order to define shear wave velocity profiles for the study area. The relationships between shear wave velocity, Standard Penetration Test (SPT) blow-counts and the soil properties were evaluated as functions of depth. SPT-based uphole tests were performed to measure shear wave velocity during drilling operations in some of the borings. The SPT-based V-s values were computed with different empirical formulas and compared with the measured SPT based uphole V-s measurements. The empirical correlations were found to require modification to provide the best correlation for this site. The depth factor was considered during the development of new empirical equations. Therefore, a site-specific formula was proposed in order to obtain V-s profiles for all layers in the study area. (C) 2011 Elsevier B.V. All rights reserved.
A Newly Developed Seismic Microzonation Model of Erbaa (Tokat, Turkey) Located on Seismically Active Eastern Segment of the North Anatolian Fault Zone (Nafz)
(Springer, 2013) Akin, Muge K.; Topal, Tamer; Kramer, Steven L.
A methodology to model seismic microzonation maps is required in the hazard mitigation decision plans of the earthquake prone areas. The stage of disaster preparedness for new residential places is of great importance for detailed seismic microzonation models. The effects of local geological and geotechnical site conditions were considered in order to establish site characterization as the initial stage of the models in this study. Dynamic soil properties based on the empirical correlations between shear wave velocity (V (s)) and standard penetration test blow counts were taken into account in order to define representative soil profiles extending down to the engineering bedrock. One-dimensional site response analyses were performed to analyze earthquake characteristics on the ground surface. The layers for soil classification, geology, depth to groundwater level, amplification, distance to fault, slope and aspect, and liquefaction-induced ground deformation potential of the study area were prepared in seismic microzonation models. The study area, Erbaa, is placed along the seismically active North Anatolian Fault Zone. Final seismic microzonation map of the study area was evaluated applying different GIS-based Multi-Criteria Decision Analysis (MCDA) techniques. Two of the MCDA techniques, simple additive weighting and analytical hierarchical process (AHP), are considered during the evaluation step of the final seismic microzonation map. The comparison is made in order to distinguish two different maps based on these MCDA techniques. Eventually, AHP-based seismic microzonation map is more preferable for the seismic design purposes in this study.
Seismic Microzonation of Erbaa, Tokat Province, Turkey, Based on Analytical Hierarchical Process
(Geological Soc Amer, inc, 2012) Akin, Muge K.; Topal, Tamer; Kramer, Steven L.
This study is to develop a seismic microzonation map using Analytical Hierarchical Process (AHP), one of the Multicriteria Decision Analysis methods based on Geographical Information Systems. The study area, Erbaa, is located along the eastern segment of the North Anatolian Fault Zone and is one of the largest towns and one of 12 districts within Tokat Province (population, similar to 176,000) in the Middle Black Sea Region of Turkey. Erbaa is located on the southwest bank of the Kelkit River. After the disastrous 1942 (M-s = 7.2) and 1943 (M-s = 7.6) earthquakes, the settlement was shifted southward. Erbaa is one of the most rapidly growing metropolitan areas of this province, with a population of similar to 96,000 people. Therefore, a microzonation study is needed for new settlement places. The data are classified as fundamental input data and derived input data, which are both considered in the AHP method. Fundamental input data include topographical, slope, aspect, lithology, and depth to groundwater table maps. The derived input data involve distance to fault, site classification based on shear wave velocity for the upper 30-m depth, amplification, and liquefaction-induced ground deformation maps, representing the seismic-based layers, produced from various analyses. Weight and rank values are assigned to different layers and to the corresponding classes of each layer. The resulting microzonation map reveals that the northern part requires detailed geotechnical investigation and that the southern part of the area is much more suitable for settlement.