Site response studies in Agartala Urban agglomeration

摘要: A systematic investigation using digital microearthquake recorders with short period SS-1 seismometers, covering 76 sites in and around Agartala city, has been carried out for site response (SR) studies the area. In northern part of area, SR varies from 1.15 to 1.85 corresponding peak frequency 0.76 0.93 Hz where soil is mostly semi-consolidated stiffer than recent Quaternary deposits (Haora River formation). southern 1.12 2.42 0.71 0.85 within Dupitila formation (early Quaternary). It observed that estimated H/V increases edges middle Haora valley impedance contrast fallows similar trend. This reflects by influenced contrast, whereas computed amplification 1-D model shows opposite The maximum at fundamental resonance, 1.04 near BH-7, 2.5 times greater contrast/ratio derived same location. Relationship between resonance depth was obtained applying quarter wavelength Bard (2000) methodologies, which linearity, its nonlinearity characteristic across River. Shear wave velocities, subsequently, SPT index factor safety (by cyclic stress approach) were geotechnical parameters. Vs30 data used this study getting a first hand information about stiffness condition estimation could be useful tool delineating liquefied none zones various levels, especially water table exists very shallow level. expected liquefiable zone depths varying 6–25 m beneath bearing percentage fines more 35% knowledge subsurface characteristics will civil engineers/city planners, can taken into account time constructing earthquake-resistant structures