| 1. |
- Ansal, A., et al.
(author)
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Seismic microzonation for earthquake risk mitigation in turkey
- 2004
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Conference paper (peer-reviewed)abstract
- As a tool to improve the state of land use management in Turkey and to better mitigate earthquake risk inthe future, a microzonation project was initiated after the 1999 Kocaeli earthquake. The project had twocomponents (a) drafting a microzonation manual [1], (b) conducting pilot case studies in the selected tworegions affected by the 1999 Marmara earthquakes [2]. The main purpose of the study was to test anddemonstrate the applicability of the methodology proposed in the Seismic Microzonation Manual preparedfor the project. The major contributions of the study are the probabilistic assessment of the regionalearthquake hazard, interpretation of the microtremor records, and interpretation of the available geologicaland geotechnical data based on a grid approach. All the available data was transformed to GIS format andthe results are evaluated to obtain a microzonation with respect to site amplification, liquefactionsusceptibility and landslide hazard. An attempt will be made to summarize the results of the pilot studyconducted for the Gölcük region to give an overview of the proposed methodology.
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| 2. |
- Ansal, A., et al.
(author)
-
Site Characterization and Site Amplification for a Seismic Microzonation Study in Turkey
- 2004
-
Conference paper (peer-reviewed)abstract
- The pilot areas were divided into cells by a grid system of 500 m x 500 m for estimating the effects of site conditions at a scale of 1:5000 by assigning representative soil profiles at the centre of each grid. These soil profiles were classified according to the Turkish Earthquake Code, NEHRP site classification, equivalent shear wave velocity and used for site response analyses. The zonation maps involve the division of the area into three zones as (A, B, and C). In all cases, the variations of the calculated parameters are considered separately and their frequency distributions were determined. Thus the zone A shows the most unsuitable 33 percentile, zone B the medium 34 percentile and zone C shows the most favorable 33 percentile. A suitable pa-rameter is considered to be the average spectral acceleration between 0.5-1.5 sec periods obtained from site response analysis. Even though more empirical, the spectral amplifi-cations calculated using equivalent shear wave velocities gave consistent values that appear to be realistic when compared with the selected soil profiles. Thus microzonation maps with respect to ground shaking were based on the average of spectral accelerations and spectral amplifications obtained from equivalent shear wave velocities.
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