The influence of focal mechanism on seismic radiation energy estimation
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摘要: 利用国家地震台网和全球地震台网的宽频带远震P波波形数据,通过测定2014—2019年间国内MW≥6.0和国外MW≥6.5共105次浅源地震的辐射能量和能量震级,研究了震源机制解对辐射能量估计的影响。结果表明:① 震源机制不同导致地震能量辐射差异较大,其中走滑型地震对辐射能量的影响最大,对能量震级的平均影响因子为0.34,正断型地震对能量震级的平均影响因子为0.08,逆断型地震对能量震级的影响最小,平均影响因子为0.05;② 不同震源机制类型地震的差震级ΔM也不同,走滑型地震的ΔM为 0.31,正断型地震的ΔM为0.21,逆断型地震的ΔM为0.08,这表明走滑型地震辐射能量的效率较高,正断型次之, 逆断型最低;③ 根据鲁甸地震的测定结果分析可知,当能矩比与慢度参数均远高于全球平均水平时,即使该地震震级较小,也存在造成严重破坏的概率;④ 能量震级Me和矩震级MW分别反映了震源的动态和静态属性,二者的联合测定对地震灾害合理评估和地震应急具有重要意义。Abstract: The measurement of radiated seismic energy has long been an important aspect of seismological studies. In this work, broadband teleseismic P-wave recordings from the China National Seismic Network and Global Seismograph Network were used to measure the radiated seismic energy and energy magnitude of 105 shallow earthquakes in and outside China (MW≥6.0 for the former and MW≥6.5 for the latter) that occurred during 2014–2019. These measurements were then used to study the effects of focal mechanism on seismic radiation energy estimation. The following findings were obtained: ① Radiated seismic energy varies widely depending on the focal mechanism. Strike-slip earthquakes have the greatest impact on radiated seismic energy (with an average increase in energy magnitude of 0.34), followed by normal earthquakes (with an average increase in energy magnitude of 0.08), and thrust earthquakes (average increase in energy magnitude of 0.05). ② The differential magnitude ΔM also varies with the focal mechanism, and the ΔM values of strike-slip, normal, and thrust earthquakes are 0.31, 0.21, and 0.08, respectively. Therefore, strike-slip earthquakes have the highest efficiency in terms of radiated seismic energy, followed by normal and thrust earthquakes. ③ Based on measurements of the 2014 Ludian earthquake, if the energy-to-moment ratio and slowness parameter are both higher than the global average, there is a chance for severe damage to occur, even at small seismic magnitudes. ④ Because the energy magnitude Me and moment magnitude MW reflect the dynamic and static attributes, respectively, of a seismic source, combined measurements of Me and MW are profoundly important for seismic danger estimation and earthquake response planning.
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Keywords:
- radiated seismic energy /
- energy magnitude /
- focal mechanism /
- moment magnitude /
- Ludian earthquake
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表 1 鲁甸和九寨沟地震的震源机制及其震级测定结果
Table 1 The focal mechanism and magnitude determination results of Ludian and Jiuzhaigou earthquakes
名称 震源深度/km 破裂时间/s 震源机制(GCMT) MS (CENC) MW (GCMT) Me0 Me1 鲁甸地震 10 42 走滑断层 6.5 6.2 6.2 6.6 九寨沟地震 9 43 走滑断层 7.0 6.5 6.3 6.6 表 2 鲁甸和九寨沟地震的相关地震参数
Table 2 The relevant seismic parameters of Ludian and Jiuzhaigou earthquakes
名称 节面Ⅰ 节面Ⅱ 地震矩M0
/1018 Nm地震能量ES1
/1014 J能矩比
/10−5慢度参数
Θ走向/° 倾角/° 滑动角/° 走向/° 倾角/° 滑动角/° 鲁甸地震 71 81 −175 340 86 −9 2.12 2.07 9.74 −4.01 九寨沟地震 151 79 −8 243 82 −168 6.98 2.29 3.28 −4.48 表 3 41次走滑型地震的地震能量变化率及相关参数
Table 3 Seismic energy change rate and relevant parameters of 41 strike-slip earthquakes
日期 ES0
/JES1
/J能量变化率 Me0 Me1 Me1−Me0 地震的参考位置 2014-02-12 4.57×1014 1.70×1015 73% 6.84 7.22 0.38 中国新疆和田地区于田县 2014-03-10 4.12×1014 1.58×1015 74% 6.81 7.20 0.39 美国加州附近海域 2014-04-12 6.10×1015 1.66×1016 63% 7.59 7.88 0.29 所罗门群岛 2014-04-24 2.54×1014 9.12×1014 72% 6.67 7.04 0.37 加拿大 2014-05-13 2.45×1014 8.81×1014 72% 6.66 7.03 0.37 巴拿马南部海域 2014-05-24 2.63×1014 1.01×1015 74% 6.68 7.07 0.39 爱琴海 2014-06-29 3.98×1014 5.43×1014 27% 6.80 6.89 0.09 南桑威奇群岛地区 2014-08-03 5.56×1013 2.14×1014 74% 6.22 6.61 0.39 中国云南鲁甸 2015-02-13 7.94×1014 2.95×1015 73% 7.00 7.38 0.38 中大西洋海岭北部 2015-04-17 6.17×1013 2.45×1014 75% 6.26 6.66 0.40 斐济群岛地区 2015-05-20 1.46×1014 3.98×1014 63% 6.51 6.80 0.29 圣克鲁斯群岛 2015-05-22 3.02×1014 6.24×1014 52% 6.72 6.93 0.21 所罗门群岛 2015-05-22 2.92×1014 8.81×1014 67% 6.71 7.03 0.32 所罗门群岛 2015-05-29 1.48×1015 3.16×1015 53% 7.18 7.40 0.22 美国阿拉斯加半岛 2015-06-17 2.54×1014 1.01×1015 75% 6.67 7.07 0.40 中大西洋海岭 2016-03-02 9.89×1015 3.94×1016 75% 7.73 8.13 0.40 印尼伊里安查亚省地区 2016-04-15 1.16×1015 4.03×1015 71% 7.11 7.47 0.36 日本九州岛 2016-04-29 6.84×1013 2.54×1014 73% 6.29 6.67 0.38 东太平洋海岭北部 2016-08-12 1.20×1015 4.62×1015 74% 7.12 7.51 0.39 洛亚蒂群岛东南 2016-08-29 9.44×1014 3.76×1015 75% 7.05 7.45 0.40 阿森松岛以北海域 2016-11-25 3.59×1014 1.33×1015 73% 6.77 7.15 0.38 中国新疆克孜勒苏州阿克陶县 2016-12-08 1.86×1014 6.68×1014 72% 6.58 6.95 0.37 美国加利福尼亚州附近海域 2016-12-08 2.04×1016 2.69×1016 24% 7.94 8.02 0.08 所罗门群岛 2017-07-06 9.66×1013 3.47×1014 72% 6.39 6.76 0.37 菲律宾 2017-07-17 5.89×1015 2.34×1016 75% 7.58 7.98 0.40 科曼多尔群岛地区 2017-08-08 6.61×1013 2.29×1014 71% 6.28 6.64 0.36 中国四川阿坝州九寨沟县 2017-08-18 7.85×1013 3.13×1014 75% 6.33 6.73 0.40 阿森松岛以北海域 2017-11-04 9.77×1014 2.24×1015 56% 7.06 7.30 0.24 汤加群岛 2017-11-30 8.71×1013 3.35×1014 74% 6.36 6.75 0.39 中大西洋海岭中部 2018-01-23 1.35×1016 3.94×1016 66% 7.82 8.13 0.31 阿拉斯加湾 2018-01-28 7.59×1013 3.02×1014 75% 6.32 6.72 0.40 布韦岛附近海域 2018-03-08 8.51×1014 2.75×1015 69% 7.02 7.36 0.34 新爱尔兰地区 2018-09-28 5.89×1015 1.14×1016 48% 7.58 7.77 0.19 印度尼西亚 2018-12-20 4.62×1015 1.50×1016 69% 7.51 7.85 0.34 科曼道尔斯基奥斯特罗娃地区 2019-04-12 4.27×1014 1.70×1015 75% 6.82 7.22 0.40 苏拉威西,印度尼西亚 2019-07-06 2.63×1014 1.05×1015 75% 6.68 7.08 0.40 加利福尼亚中部 2019-07-07 1.48×1015 3.27×1015 55% 7.18 7.41 0.23 莫鲁卡海北部 2019-07-14 1.20×1015 4.79×1015 75% 7.12 7.52 0.40 西澳大利亚 2019-09-25 2.00×1014 6.68×1014 70% 6.60 6.95 0.35 印度尼西亚塞拉姆 2019-10-29 6.46×1014 2.32×1015 72% 6.94 7.31 0.37 棉兰老岛,菲律宾 2019-11-04 1.57×1014 6.24×1014 75% 6.53 6.93 0.40 汤加群岛 平均值 68% 0.34 -
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