CHAPTER - 1
INTRODUCTION
1.1. GENERAL
The feasibility of a potentially damaging phenomenon occurring within a specified span of time and within a given area is termed as a natural hazard. When the human societies, living things and built environment are troubled by any of the natural hazards, then it is considered as a disaster. Earthquakes are the most horrific natural disaster without leaving much scope for prevention of hazard after the occurrence of the event especially because of its inherent nature to unleash destruction in the large area spontaneously. The abrupt displacement of rock masses within the upper 15-50 km of the earth’s crust produces a sudden motion or vibration of the ground which felt as earthquakes. During the earthquake, the earth surface shakes and vibrates because of the group of waves which are radiated outwards from an abruptly disturbed zone in the Earth’s crust, or mantle. It remains to be the sterling calamity happening anytime in the human history. The hazards caused by the earthquakes are specified as seismic hazards. The large earthquakes which occurred in the last three decades have caused heavy loss of lives and wide physical demolition throughout the…show more content… He measured the shear wave velocity and thickness of soil at 50 locations using the MASW (Multi-channel Analysis of Surface Waves) technique. To obtain the site response and amplification spectra, the measured velocity of shear waves and seismic inputs of recent earthquake occurred in Chamoli are used in SHAKE 2000 software. After the analysis they determined that, compared to the southern part of the study area the northern part shows higher shear wave velocity. Also it suggests the range of peak amplification for northern part as 1-1.5 Hz, for central part 2-2.5 Hz and for southern part it is 3-4