Abstract:
Seismic hazards and their damages have been substantially more serious on unconsolidated or soft rocks then on rock sites even if they are very close to Earthquake epicenter. To find or characterize shallow subsurface soil by usage of shear wave velocity
is an important method in practice. Passive techniques based on recordings of ambient noise are very appealing instruments for estimating the velocity and thickness of soil layers. These methods are in fact very cheap and noninvasive exploration alternatives. For this thesis, methods of MAM (Multi-array analysis of microtremor) and MASW (Multi channel analysis of surface waves) were utilized to calculate shear wave velocity of Kachnar Park Islamabad. Three MASW and one MAM survey was conducted. A total of 72 geophones, 3 channels were used. The distance between two geophones were kept at 5 meter. After acquiring data, it was processed using the Geopsy module. The dispersion curve was developed using F-K analysis and then inverted to calculate shear wave velocity. Velocity of shear waves is in between 282-303 ms-1. This range of velocity falls in D ground type according to NEHRP codes. This indicates in subsurface there is stiff soil or medium or dense deposits of sand. They can increase or amplify ground shaking during seismic hazards. Vs 30 curve of Kachnar Park was developed. Contour map of Islamabad was developed using data of F9 Park, I-8/3 (Kachnar Park), COMSATS University and Jasmine Garden. From these study engineers can create building code based on shear wave velocity value and NEHRP code and can develop buildings, projects and structures based on these codes that can prevent any seismichazard and can save many lives and can prevent financial losses.
