MICROZONATION OF THE AMBIENT SEISMIC BACKGROUND NOISE IN AUJA DISTRICT

Abstract:

The city of Aluja is one of the important of Palestinian cites, we present the spatial distribution of the natural periods over a map which shows the important of characteristics of soil deposit which will effect significantly on the mitigation of the seismic risk impacts. The microtremors are very important and useful measurements in site response which could be compensated the shortage and deficiency of the seismic recorded data, especially when there are missing of seismic stations for a long time. The aim of this study is to prepare a GIS-based microzonation map of the Aluja settlement area for the purposes of urban planning theme.The predominant natural frequency at each site was determined using the Horizontal to Vertical Noise Ratio (HVNR) of the microtremors records. It was applied to 100 points which cover the study area.The areas were divided into cells by a grid system of 300 m x 300 m for estimating the effects of site conditions.Using the outputs of these results, to classify the area in three zones with frequencies ranging from 0.5-0.8, 0.8-1 and 1-1.5 Hz. The impedance contrast of soil deposit of sediments which shown this distribution of frequencies.