Data Processing And Preliminary Application Of Airgun Source In Hutubi Xinjiang

Seismic wave is a beacon light to bright the interior earth. Using seismic wave to study internal structure of the earth is the most important way to understand the internal of the earth. With the continuous development of the seismology, people are no longer content to study the internal of the earth by the earthquake. More and more people use active seismic source to study the internal of the earth activity. It is a very important way to study the character of the medium, fault structure, earthquake prediction. Airgun source is a high power, low frequency, high-efficient, environmental source. It is a perfect active source to study the internal structure of the earth.In this paper, we introduce the development progress, signal excited, signal characteristics of the airgun source in Hutubi Xinjiang. We use the signal which recorded by the stations based on the digital seismograms of Xinjiang to study the attenuation and the travel-time of the airgun source using stacking and correlation. Then we get these results:(1) Frequency of the signal emitted by the airgun source in Xinjiang is 2-6Hz.The power of 6 airguns is equaled to the power of Ms0.9 earthquake. We can find the signal at the station that 380 km along the airgun source after stacking.(2)After stacking, we can find the Pn wave above 200 km from the equivalent section. And the traveltime of the airgun source is equal to the earthquake above 200 km.(3) We choose the signal generated by airguns which record by 8 stations in the northern Tien Shan based on the digital seismograms of Xinjiang,conclude the RMS of amplitude spectrum between 2Hz to 6Hz after stacking,and let the RMS(root mean square) values represent the amplitude of the station. Then we fit these RMS values with attenuation equation,and we obtain the Qp=174±29,Qs=523±65,when the frequency is 4Hz.(4)Using the interferometer of the signal after deconvoluted with the source, we get the change of the travel-time in different phase. We choose the STZ station as an example, and we find the change of the travel-time is increasing before the Ms5.1 earthquake in Urumqi Xinjiang at August 30 th 2013. Then the travel time is declined after the earthquake. After preliminary analysis, we think it is because of the stress accumulated and stress released during the earthquake.Using the airgun source to monitor the change of the travel-time inland is a new attempt in seismology. It have foundations for geological medium observation and the picture of the 4D cloud.