Study On Site Ee Ct Base On Data Of Seismic Array

Site amplification of strong motion, which is closely related with the destructibility of earthquake, has been a subject of intense interest in the field of earthquake engineering. For lack of data of strong motion, however, other observational data has been applied to this topic.Seismic array is composed of a group of seismometer which is arranged according to the set of structure. Seismic array observation system is established for micro-tremor observation. Large-aperture seismic array can supply with abundant data because of its vast coverage area and considerable record length. Then using data of seismic array to study site effects become the purpose of this article.This paper is divided into two parts according to the large-aperture seismic array:North China array and Himalaya array.Method conceived by Steven Taylor is referred in this paper for North China array. FK spectrum of ambient noise is regarded as input, auto-spectral spectrum is regarded as response, ratio between them can represent site amplification. There is some difference in this paper, FK spectrum of cross-correlation function of ambient noise is computed, from which velocity and azimuth of the maximum is get. Fourier spectrum of all stations is corrected to the reference point according to this velocity and azimuth, the average of all stations is used to compute FK spectrum which contains amplitude element of ambient noise. Amplification factors of all stations between10s and20s are computed, and ration between the largest one and the smallest one is about7. After standardization, relative results display that site amplification factors of Plain, which is basically consistent with sediment thickness of Bohai Bay Basin, is apparently larger than that of Mountain.In consideration of the characteristic of a large number of earthquake records, H/V method which is conceived by Nakamura is introduced in this paper to study the site effects of Himalaya array. Influence on earthquake’s H/V spectrum of Hypocenter and propagation path is discussed in this paper, and instability of H/V spectrum in the high frequency part can be observed when focal distance is different. In addition to that, H/V spectrum of micro-tremor and seismic of100 stations, which have more than20seismic records, are compared, and result that the obvious peak suggests well coherence is get. On this basis, stations are divided into four categories and method of measuring site predominant frequency is put forward. In the end of this paper, predominant frequency of these station sites is given.