09-10-2014, 03:24 PM
Ground motion characteristics of the Himalayan earthquakes have been studied from the 198 horizontal component records and 99 vertical component records from six earthquakes in the region that are now available. The characteristics studied are the peak parameters, duration of strong shaking, shape of elastic response spectra and ductility reduction factor. It is found that wean A/V ratio is quite high in the region and does not vary much with the distance from the shock-source. A study of shape of elastic acceleration response spectra revealed that: (1) shape varies s hat insignificantly- with the distance, (2) shape of spectra in the in the intermediate period range highly depends on earthquake magnitude, (3) there is a urgent need to revise the shape of response spectra recommended in IS:1893-1984, and (4) shape of "standard spectra suggested by AERB for rock sites is comparable with the mean-plus-me-standard-deviation shape from the data. Both, the ratios of peak parameters and elastic response spectra indicate that with distance the attenuation of waves of different