Probabilistic Seismic Hazard Analysis In Tehran And Adjacent Area
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Date
2015-01
Authors
ARAGHI, NOUSHIN NARAGHI
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Abstract
In the current study, probabilistic seismic hazard assessment (PSHA) for Tehran and adjacent area has been performed. Probabilistic seismic hazard analysis (PSHA) is the most widely used procedure for seismic hazard assessment. PSHA displays the probabilistic nature of seismic hazard by integrating the contributions of all possible magnitude earthquakes and locations in a consistent manner. A uniform earthquake catalogue is an essential tool in any seismic hazard analysis. In this study, an earthquake catalogue of Tehran and adjacent areas was compiled by merging international and local databanks. The standardization of the catalogue in terms of magnitude was achieved by the conversion of all types of magnitude into moment magnitude by using the orthogonal regression technique. In the newly compiled catalogue, all aftershocks and foreshocks were detected and eliminated from the catalogue. The study area is divided into two seismic regions based on their seismotectonic regime. The seismic sources have been defined as fault sources and area sources. The seismicity parameters and minimum magnitude of completeness were calculated separately for the faults and each seismic zone in the area. Four attenuation relationships and three new generation attenuation relations (NGA) have been selected and considered for this study. Peak ground acceleration (PGA) is not sufficient to design for the modern building codes, so PGA along with spectral acceleration values have been estimated and used in period of 0.2 s and 1.0 s.
Seismic hazard analysis was performed in selected points and the hazard maps for horizontal peak ground acceleration and spectral acceleration (T=0.2 sec and T=1.0
xix
sec) for different return periods (475, 975, and 2475 years) have been produced and compared with those available in literature.
Maps in this study show higher estimate levels of peak ground acceleration and response spectral accelerations expected in various return periods than those produced in the earlier researches. The new model is therefore expected to result in considerable modifications to the building code.
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Keywords
Probabilistic Seismic Hazard , Analysis In Tehran And Adjacent Area