Diffusion of seismic waves in layered media: boundary conditions and analytical solutions     

Ulrich Wegler 《Geophysical Journal International》2005,163(3):1123-1135

  相似文献   

Distribution of Lg coda Q in Xinjiang and its adjacent regions     

徐彦  毛燕  胡家富  苏有锦  丛连理 《地震学报(英文版)》2005,18(2)

Introduction Lg wave is usually considered as one of the most prominent phases recorded by short-period or broadband seismometers in the continental area. Therefore, it is often used to determine the magnitude of regional earthquakes, the yield of nuclear explosions (Nuttli, 1986) and the horizon-tal variations of crustal attenuation. A theoretical ray approach shows that Lg is the superposition of higher-mode surface waves propagating in the continental crust (Knopoff et al, 1973; Panza and…  相似文献   

Coherent backscattering of acoustic waves in the near field     

L. Margerin  M. Campillo  B. A. van Tiggelen 《Geophysical Journal International》2001,145(3):593-603

  相似文献   

Regional features of coda attenuation of aftershocks of Wuding, Yunnan earthquake in near field     

秦嘉政  李白基  钱晓东  苏有锦  蔡静观  付虹 《地震学报(英文版)》2001,14(1):91-100

IntroductionSeismic wave is an important information source to analyze and study seismic source and internal structure of the earth. Studies of wave on different frequency ranges can provide many features of seismic source and internal structure of the earth. In recent years in quantitative study of seismic wave seismologists at home and abroad have developed a wide study field on the coda. Especially seismologists have done a lot of work in coda geneses, mechanism and its attenuation to explo…  相似文献   

Studying the depth-dependent variation of site magnification factor in Dongchuan by earthquakes observed in borehole     

罗娣华  蒋乐群  陈敏恭  叶建庆  蔡少平  刘学军  LIU Xue-jun 《地震学报(英文版)》2001,14(1):72-81

IntroductionMany seismologists both at home and abroad have recognized the importance of site effect on structures of damaging earthquakes. Lots of great earthquakes occurred in China and foreign countries clearly indicate that the site response of buildings located in the seismic area has huge impact on the damage of building(s structure (JIANG, et al, 1997). The digitization of seismometer and development of computer have laid foundation of substance for quantitatively studying spatial var…  相似文献   

宁夏及邻区尾波Q值分布特征   总被引：1，自引：0，他引：1  

赵卫明  刘秀景  马禾青 《华南地震》2002,22(1):23-27

应用宁夏9个台站1986年后记录的宁夏及邻区132次地震的200条DD－1仪模拟记录，对宁夏及邻区的分区尾波Q值进行了研究，结果表明，分区尾波Q值主要与地质构造有关。Q值相对较低的区域为吉兰泰盆地，银川盆地南段的吴忠，灵武，阿拉善左旗西南，中卫至海原之间，吴忠，灵武至盐池之间；相对较高的区域为乌海及附近，贺兰山，永宁至大武口之间。  相似文献   

Regional coda Q in Costa Rica, Central America     

Victor Gonzalez  Leif Persson 《Journal of Seismology》1997,1(3):269-287

Regional seismic apparent attenuation was estimated for Costa Rica, Central America, by using a time domain single scattering model of the shear wave coda decay of local earthquakes. The sensitivity of coda Q (Q_c) measurements with respect to geological differences in the crust is demonstrated in eight sub-regions with a large variety of tectonic and geologic properties. The Q_c estimations were performed for 96 selected local earthquakes recorded at 13 sites during a period of three months. In order to model the scattering as a weak process and to avoid short distance nonlinear effects, we made use of the S-wave coda data only from events within a hypocentral distance of 12 to 106 km with a lapse time between 9 and 53 s. Seismograms were also divided into groups with three different focal depths d, namely d<21 km, 21 kmc values are frequency dependent in the range 1–9 Hz, and are approximated by a least-squares fit to the power law Q_c(f) = Q₀(f/f₀)ⁿ. The estimated parameters of the power-law dependence of Q_c for the whole region, including all depths and possible wave paths, are Q₀ = 91 (± 8.4) and n = 0.72 (±0.071). Differences in the parameter of Q_c for different depths intervals are small, ranging from Q₀ = 90 (±0.7) and n = 0.70 (±0.006) for the uppermost group, with focal depths less than 21 km, to Q₀ = 97 (±0.7) and n = 0.79 (±0.005) for the deepest group with focal depths larger than 43 km. The regional differences in Q_c for the eight sub-regions are significantly larger when compared with the differences between the three focal depth groups. An attempt is made to interpret the variation of Q_c in terms of spatial variations in the geologic and tectonic properties of the crust. Other authors have found that the frequency exponent n might be larger in active tectonic areas and smaller in more stable regions. In the northern region of the Pacific coast we obtain a value of n = 0.52 (±0.011), which might indicate a lower level of tectonic activity when compared with n = 0.85 (±0.015) and 0.83 (±0.031), respectively, for the central and southern sub-regions along the Pacific coast. The latter two sub-regions are located closer to the active area near the Cocos ridge. We obtain the frequency exponent n = 0.72 (±0.052) along a major shear zone in central Costa Rica characterized by high volcanic activity and large geologic complexity. Values of n along the Panamean border are 0.62 (±0.029) in the north and 0.86 (±0.009) and 0.83 (±0.031) in two regions adjacent to the subduction zone and the Cocos Ridge, respectively.  相似文献   

Coda Q in two-layer random media     

Kiyoshi Yomogida  Keiiti Aki  Rafael Benites 《Geophysical Journal International》1997,128(2):425-433

  相似文献   

Chaotic behaviour of coda waves in the eastern Pyrenees     

Antoni M. Correig  Merce Urquizu 《Geophysical Journal International》1996,126(1):113-122

  相似文献   

腾冲火山及其周围地区的地壳Q值特征   总被引：9，自引：4，他引：5  

秦嘉政  皇甫岗 《地震研究》1998,21(4):358-361

本利用腾冲火山活动区及周围地区的地方震尾波资料。根据尾波散射理论,研究了火山地区及周围地区的地壳Ｑ值。结果表明,火山地区的地壳Ｑ值最低。为９５,近邻区的龙陵－－保山地区的１７０－１５０之间。,周围地区最高达２９５左右。是火山地区的１．８－３．０倍左右。地壳Ｑ值的空间２明显表现出腾冲火山活动区为低Ｑ值区,而周围地区为高Ｑ值地区,这种地壳Ｑ值的空间２差异也许反映了火山地区内部介质状态与周围地区构造地  相似文献