| Characteristics of head wave in multi-layered half-space |
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| 作者姓名： | 张坚 张海明 陈晓非 |
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| 作者单位： | DepartmentofGeophysics，PekingUniversity，DepartmentofGeophysics，PekingUniversity，DepartmentofGeophysics，PekingUniversity Beijing100871，China，Beijing100871，China，Beijing100871，China |
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| 基金项目： | State Natural Science Foundation of China (40074008) and State Key Basic Research Development and Program-ming Project (G1998040702). |
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| 摘 要： | Introduction Head wave is one of the main phases of local seismic arrivals, and it is important in the study of the crustal structure and the physical characteristics of the transition-zone between the crust and the mantle. So far, the kinetic characteristics of head wave such as arrival time have been widely used, while the dynamic characteristics of head wave like amplitude were usually ignored al-though it includes more information of the structure. In this article, we shall investigate the…
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| 收稿时间： | 15 May 2002 |
| 修稿时间： | 7 October 2002 |
Characteristics of head wave in multi-layered half-space |
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| Zhang Jian , Zhang Hai-ming and Chen Xiao-fei.Characteristics of head wave in multi-layered half-space[J].Acta Seismologica Sinica(English Edition),2002,15(6):585-594. |
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| Authors: | Zhang Jian Zhang Hai-ming and Chen Xiao-fei |
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| Institution: | Department of Geophysics, Peking University, Beijing 100871, China |
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| Abstract: | In this article, we analyze the dynamic characteristics of head wave in multi-layered half-space media models with high-velocity layer or low-velocity layer, and the model with a continuous transition-zone between the crust and the mantle by using synthetic seismogram. It is concluded that the dynamic characteristics of head wave are sensitive to the thickness and velocity of the high-velocity layer. There is obvious diffraction phenomenon of seismic wave if the thickness of high-velocity layer is very small compared with the characteristic wavelength. In this case, the high-velocity layer cannot shield the head wave propagating along the upper interface of the media below it, and the amplitude of this head wave is proportional to the thickness or the velocity of the high-velocity layer. When the thickness of high-velocity layer is nearly identical to the characteristic wavelength of seismic wave, the wave phases reflected from the bottom of the high-velocity layer and the head wave phase may have very close arrival and weaken each other because of destructive interference. As to low-velocity layer, the amplitude of the head wave is weak and decreases with the velocity of this layer. It is also found that if a continuous transition-zone between the crust and the mantle is introduced, we can get a strong apparent head wave phase in synthetic seismogram and the amplitude of this phase increases with the thickness or velocity gradient of the transition-zone. |
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| Keywords: | synthetic seismogram head wave high-velocity layer low-velocity layer transition-zone be-tween crust and mantle |
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