Focal mechanism and moment tensor in orthorhombic anisotropic media

TANG Jie1 WEN Lei1 WANG Hao1 ZHANG Wenzheng1

(1.School of Geosciences, China University of Petroleum (East China) , Qingdao, Shandong, China 266580)

【Abstract】Hydraulic fracturing zones have anisotropic characteristics on the whole. It is necessary to analyze the influences of anisotropic parameters on focal mechanism and moment tensor. This paper studies the shear–tensile focal mechanism and seismic moment tensor when the source is located in anisotropic media. It analyzes the influences of focal anisotropy on double couple (DC) components, compensated linear vector dipole (CLVD) components, and isotropic (ISO) components. The seismic response characteristics of dry and saturated orthorhombic anisotropy media are also analyzed. The effects of crack parameters and fluid parameters on seismic response are discussed. The following results are obtained based on our research. A. The moment tensor in anisotropic media can be obtained by anisotropic parameters and source quantity. B. The non-DC components caused by shear–tensile crack depend on the rupture mode, type of anisotropic media, crack parameter and section strike. High ISO components appear in dry cracked media and high CLVD components appear in water saturation media. C. Far field P-wave radiation patterns are different between isotropic and anisotropic media. The source characteristics and medium anisotropy have significant impacts on the seismic wave travel time, amplitude, and polarity.

【Keywords】 orthorhombic anisotropy; microseismic; focal mechanism; moment tensor; shear–tensile source;


【Funds】 National Natural Science Foundation of China (41504097, 41874153)

Download this article


    [1] Rong Jiaojun, Li Yanpeng, Xu Gang et al. Fracture detection with microseismic. OGP, 2015, 50 (5): 919–924 (in Chinese).

    [2] Fang Bing, Sun Chengyu, Tang Jie et al. Analysis of frequency characteristics of micro–seismic signals. OGP, 2015, 50 (3): 411–417 (in Chinese).

    [3] Tang Jie, Wang Hao, Wen Lei et al. Focal mechanism of shear–tensile microseismic and amplitude distribution characteristics. OGP, 2018, 53 (3): 502–510 (in Chinese).

    [4] Cai Xiaogang, Yao Chen, Chen Xiaofei. Seismic moment tensor in anisotropic ATI media: shear faulting. Chinese Journal of Geophysics, 2011, 54 (7): 1772–1782 (in Chinese).

    [5] VavryCuk V. Focal mechanisms in anisotropic media. Geophysical Journal International, 2005, 161 (2): 334–346.

    [6] VavryCuk V. Focal mechanisms produced by shear faulting in weakly transversely isotropic crustal rocks. Geophysics, 2006, 71 (5): 145–151.

    [7] Chapman C H, Leaney S. A new moment-tensor decomposition for seismic events in anisotropic media. Geophysical Journal International, 2014, 199 (3): 1808–1810.

    [8] Leaney W S. Microseismic Source Inversion in Anisotropic Media [D]. University of British Columbia, 2014.

    [9] Tomas F, Alice G. Shear and tensile earthquakes caused by fluid injection. Geophysical Research Letters, 2011, 38 (5): 387–404.

    [10] Tsvankin I, Gaiser J, Grechka V. Seismic anisotropy in exploration and reservoir characterization: An overview. Geophysics, 2010, 75 (5): 15–29.

    [11] Sil S,Sen M,Gurevich B. Analysis of fluid substitution in a porous and fractured medium. Geophysics, 2011, 76 (3): 157–166.

    [12] Tang Jie, Fang Bing, Sun Chengyu et al. Study of seismic wave propagation characteristics based on anisotropic fluid substitution in fractured medium. GPP, 2015, 54 (1): 1–8 (in Chinese).

    [13] Schoenberg M, Sayers C. Seismic anisotropy of fratured rock. Geophysics, 1995, 60 (1): 204–211.

    [14] Krief M, Garat J, Stellingwerff J et al. A petrophysical interpretation using the velocities of P and S waves (full-waveform sonic). Log Analyst, 1990, 31 (6): 355–369.

    [15] Huang L, Stewart R, Sil S et al. Fluid substitution effects on seismic anisotropy. Journal of Geophysical Research. 2015, 120 (2): 850–863.

    [16] Sayers C M, Kachanov M. Microcrack-induced elastic wave anisotropy of brittle rocks. Journal of Geophysical Research, 1995, 100 (3): 4149–4156.

    [17] Gurevich B. Elastic properties of saturated porous rocks with aligned fractures. Journal of Applied Geophysics, 2002, 54 (3): 203–218.

    [18] Vavrycuk V. Tensile earthquakes: Theory, modeling, and inversion. Journal of Geophysical Research, 2011, 116 (12): B12320.

    [19] Vavrycuk V. Moment tensor decompositions revisited. Journal of Seismology, 2015, 19 (1): 231–252.

    [20] Vavrycuk V. Inversion for anisotropy from non-double-couple components of moment tensors. Journal of Geophysical Research, 2004, 109 (7): 632–641.

    [21] Grechka V. Tilted TI models in surface microseismic monitoring. Geophysics, 2015, 80 (6): 11–23.

    [22] Hudson J A, Pearce R G, Rogers R M. Source type plot for inversion of the moment tensor. Journal of Geophysical Research Atmospheres, 1989, 94 (1): 765–774.

    [23] Aki K, Richards P G. Quantitative Seismology. University Science Books, 2002, Sausalito, CA, USA.

    [24] Tang Jie, Fang Bing, Sun Chengyu et al. Study on focal mechanism of micro-seismic induced by hydrofracture and signal propagation characteristics. OGP, 2015, 50 (4): 643–649 (in Chinese).

    [25] Yao ZhenJan, Sun Chengyu, Tang Jie et al. Micro-seismic forward modeling in viscoelastic anisotropic media based on different focal mechanisms. OGP, 2017, 52 (1): 63–70 (in Chinese).

This Article


CN: 13-1095/TE

Vol 53, No. 06, Pages 1247-1255+1114

December 2018


Article Outline


  • 1 Introduction
  • 2 Shear-tensile source model in orthorhombic anisotropic media
  • 3 Characteristics of the source in orthorhombic anisotropic media
  • 4 Characteristics of microseismic wave field in orthorhombic anisotropic media
  • 5 Conclusions
  • References