| Seismic record is a record coupled with seismic source, path, instrument and site. Study on seismic source information, path attenuation, site response and so on based on seismic records is the reverse of the decoupling process. It is an important content of seismic research to extract characteristics of seismic mechanical parameters, propagation media characteristics, site characteristics from seismic record, based on the theory of seismology, through a variety of computing technology. And it is effective way to understand the process of earthquake preparation, development, occurs and the background and other structural features of earthquake preparation. In this study, three areas of work were carried out based on the latest cutting-edge computer technology and the cutting-edge seismology theory methods.In the study, on the basis of the reverse two-station spectral ratio method, a joint inversion method which allows simultaneous determination of Lg wave attenuation and site response from spectral amplitude ratios was developed. Compared with the reverse two-station spectral ratio method, this method reduced the data constraints, increased the amount of available data, obtain the site response parameters, besides the seismic wave attenuation parameters. This is the first part of this research and is the groundbreaking work in this study. The method was used successfully for estimating site response of Zhejiang seismic network statgions and Metropolitan area seismic network station, and applied to invert for the parameters of Lg wave attenuation corresponding region. The comparison with other results suggested that our results are highly reliable.In the second part, the study on seismic coda attenuation was carried out based on weak scattering theory of coda. The principle and method of coda attenuation parameter calculation based on Aki and Sato model were elaborated, and the effect of different filters and their properties, seismic noise, data sampling, coda lapse time on the calculation results were analyzed quantitatively. According to the calculation features, the dynamic sampling method was proposed for Aki model, and the best linear segment automatically determining algorithm was proposed for Sato model. Studies on calculation method have shown that the result used dynamic sampling method was more stable than that used static sampling when the fitting data were shorter. If the selection of filter and its properties didn’t cause the waveform distortion, it would not affect the result.Selecting the digital seismic data recorded by Zhejiang region earthquake network, Ningxia region earthquake network and metropolitan earthquake network in recent years, we calculated Qc(f) value of coda in relative region, polyfited relationship between Qc(f) value and frequency in corresponding region. Considering the seismic activity, we studied the relationship between the attenuation parameters of seismic wave and the seismic activity. According to the data We constructed Qo images and analyzed the relationship between images and region’s historical seismic activity in northern China.Studies have shown that the value of the coda Qo was related to not only local topography and geological structure near the location of the stations but also the seismic activity, seismic-geology of the region that the seismic wave pass through. The higher the level of seismic activity, the faster seismic wave attenuation, coda Qo is smaller. In the study, we found that the coda attenuation parameter Qo is negatively correlated withη. The effect of small earthquake sequences on the attenuation of the media in corresponding region has shown that the attenuation parametersηdropped with tendency, but Qo didn’t have the characteristics of tendency.In the third part, we selected the digital seismic data of Shanxi reservoir earthquake recorded by fixed stations and temporary stations, With these data we carried out on the earthquake location, a small local earthquake source parameters, attenuation of seismic waves, integrated surface solutions of small earthquakes and other research. In the earthquake location, the nonlinear virtual travel time equation was linearized and solved, and the source position, initial virtual velocity and travel time residuals were obtained. Then taking two times the standard deviation as a time residuals to calculate maximum error generated from longitude, latitude, depth and virtual velocity. The genetic population was structured using the maximum error and the end result of earthquake location was obtained by genetic algorithm. Using this method, the results significantly reduce travel time residuals, location quality has improved significantly compared to with the results of Zhejiang Province Network hypo81 positioning. Reservoir earthquake location shows that:the earthquake is largely concentrated in a nearly vertical, north west of the fault plane, whose normal and north angle of 46°, and east angle of 44°, and vertical angle of 87°. The result is in agreement with that of small earthquake comprehensive mechanism solution. The average depth of the earthquake 4.7km, maximum depth of 9.5km, the minimum depth of 1.7km. Epicenter was northwest narrow band distribution, and focal depth increased along the northwest direction. There is a seismic discontinuities space segment at about 3.5km the northwest end of the strip. The characteristics source parameters obtained by using the Brun model significantly different from that tectonic earthquakes. Seismic stress drop is about more than the 0.33 MPa, the average stress drop 0.88Mpa. According to the stress drop spatial distribution, the seismic discontinuities space segment at the northwest end of the strip is a low stress drop one.According to the data processing requirements, this study developed a user-friendly digital seismic processing software, The software is fully functional, data input, output and parameter configuration easy to operate, the software is running to save memory, speed, flow control. |
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