We applied the g CAP algorithm to determine 239 focal mechanism solutions 3：0≤MW≤ 6：0） with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms（including 447 previous r...We applied the g CAP algorithm to determine 239 focal mechanism solutions 3：0≤MW≤ 6：0） with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms（including 447 previous results） for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum（r1） and minimum（r3） principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations（i.e., maximum and minimum horizontal compressive stress axes： S H and S h, respectively） accordingly and found an abrupt change near ＊26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress（i.e., maximum strain axis） S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further toNE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere.展开更多
In mining, reservoir impoundment and hydraulic fracturing exploitation, the induced microseismic clusters may present complex waveforms at receivers since the individual events generally arrive very close. And the rou...In mining, reservoir impoundment and hydraulic fracturing exploitation, the induced microseismic clusters may present complex waveforms at receivers since the individual events generally arrive very close. And the routine methods for arrival picking are insufficiently efficient due to these strong influences. Here, we modified the empirical green function method and applied it to extract the green functions and the radiation coefficients of microseismic events with the largest energy in clusters.Multiple-channel records were used to estimate an "average" source spectrum and then the "average" source wavelet was removed from the records by deconvolution. We applied this method to the real data,and the result indicated clear improvement in extracting the dominant event of the clusters.展开更多
利用位于青藏高原东南缘云南地区的中国地震科学探测台站（C h in A ra y ）一期3 0 0 多个宽频带流动台站记录到的X K S 波形（包括SKS，S K K S， PKS）进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向（φ） 在26-27&...利用位于青藏高原东南缘云南地区的中国地震科学探测台站（C h in A ra y ）一期3 0 0 多个宽频带流动台站记录到的X K S 波形（包括SKS，S K K S， PKS）进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向（φ） 在26-27°N 附近,从北部的近N -S 向突变为南部的近E-W 向.研究区西部喜马拉雅东构造结附近的结果较好地反映了岩石层左旋剪切变形下发育的各向异性.26°N 以南地区,快波分裂方向以E-W 向为主,与中上地壳最大张应力的方向一致,表明云南地区整个岩石层都可能处于纯剪切变形环境.但是该区岩石层厚度不足80k m ,产生的X K S 分裂快慢波时差（〈0.7s）仅能解释部分观测值（0.9-1.5s） .因此,软流层中的各向异性对于该地区的S 波分裂结果（快波偏振方向为N W -S E 和近E-W 向）可能产生了重要的作用.一方面,N W - S E 向快波偏振方向可能反映了缅甸块体的俯冲及其随后撤退引起的上地幔流动造成的各向异性.另一方面,伴随着高原构造演化发生的从青藏高原向中国东部的软流层物质流动,以及由于绝对板块运动造成的软流层顶部的剪切作用,将产生快波方向为近E-W 向的各向异性.本研究结果为研究青藏高原东南缘不同深度的变形特征及其差异提供了重要的信息,尤其在研究青藏高原的构造抬升及其向东南缘的扩展方面产生了新的认识.展开更多
基金supported by the National Natural Science Foundations of China (No.41204040)China National Special Fund for Earthquake Scientific Research in Public Interest (Nos.201008001, 201308011)Most figures were made using GMT (Wessel et al.2013)
文摘We applied the g CAP algorithm to determine 239 focal mechanism solutions 3：0≤MW≤ 6：0） with records of dense Chin Array stations deployed in Yunnan,and then inverted 686 focal mechanisms（including 447 previous results） for the regional crustal stress field with a damped linear inversion. The results indicate dominantly strike-slip environment in Yunnan as both the maximum（r1） and minimum（r3） principal stress axes are sub-horizontal. We further calculated the horizontal stress orientations（i.e., maximum and minimum horizontal compressive stress axes： S H and S h, respectively） accordingly and found an abrupt change near ＊26°N. To the north, S H aligns NW-SE to nearly E-W while S h aligns nearly N-S. In contrast, to the south, both S H and S h rotate laterally and show dominantly fan-shaped patterns. The minimum horizontal stress（i.e., maximum strain axis） S h rotates from NW-SE to the west of Tengchong volcano gradually to nearly E-W in west Yunnan, and further toNE-SW in the South China block in the east. The crustal strain field is consistent with the upper mantle strain field indicated by shear-wave splitting observations in Yunnan but not in other regions. Therefore, the crust and upper mantle in Yunnan are coupled and suffering vertically coherent pure-shear deformation in the lithosphere.
基金supported by the National Natural Science Foundation of China(Grant:41404038)the Natural Science Foundation of Jiangsu Province(Grant:BK20130570)the National Key R&D Program of China(2016YFC0600302)
文摘In mining, reservoir impoundment and hydraulic fracturing exploitation, the induced microseismic clusters may present complex waveforms at receivers since the individual events generally arrive very close. And the routine methods for arrival picking are insufficiently efficient due to these strong influences. Here, we modified the empirical green function method and applied it to extract the green functions and the radiation coefficients of microseismic events with the largest energy in clusters.Multiple-channel records were used to estimate an "average" source spectrum and then the "average" source wavelet was removed from the records by deconvolution. We applied this method to the real data,and the result indicated clear improvement in extracting the dominant event of the clusters.
文摘利用位于青藏高原东南缘云南地区的中国地震科学探测台站（C h in A ra y ）一期3 0 0 多个宽频带流动台站记录到的X K S 波形（包括SKS，S K K S， PKS）进行了 S 波分裂分析.X K S 分裂结果最主要的特征是快波偏振方向（φ） 在26-27°N 附近,从北部的近N -S 向突变为南部的近E-W 向.研究区西部喜马拉雅东构造结附近的结果较好地反映了岩石层左旋剪切变形下发育的各向异性.26°N 以南地区,快波分裂方向以E-W 向为主,与中上地壳最大张应力的方向一致,表明云南地区整个岩石层都可能处于纯剪切变形环境.但是该区岩石层厚度不足80k m ,产生的X K S 分裂快慢波时差（〈0.7s）仅能解释部分观测值（0.9-1.5s） .因此,软流层中的各向异性对于该地区的S 波分裂结果（快波偏振方向为N W -S E 和近E-W 向）可能产生了重要的作用.一方面,N W - S E 向快波偏振方向可能反映了缅甸块体的俯冲及其随后撤退引起的上地幔流动造成的各向异性.另一方面,伴随着高原构造演化发生的从青藏高原向中国东部的软流层物质流动,以及由于绝对板块运动造成的软流层顶部的剪切作用,将产生快波方向为近E-W 向的各向异性.本研究结果为研究青藏高原东南缘不同深度的变形特征及其差异提供了重要的信息,尤其在研究青藏高原的构造抬升及其向东南缘的扩展方面产生了新的认识.
