| 一种地方与区域地震震源机制反演技术:广义极性振幅技术(二)——对实际震例的应用 |
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| 引用本文： | 严川,许力生,张旭,李春来,许康生.一种地方与区域地震震源机制反演技术:广义极性振幅技术(二)——对实际震例的应用[J].地球物理学报,2015,58(10):3601-3614. |
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| 作者姓名： | 严川 许力生 张旭 李春来 许康生 |
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| 作者单位： | 1. 中国地震局地球物理研究所, 北京 100081;
2. 甘肃省地震局, 兰州 730000 |
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| 基金项目： | 中国地震局地球物理研究所基本业务费(DQJB14B01)和国家自然科学基金课题(41474046)联合资助. |
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| 摘 要： | 为了检验广义极性振幅技术(GPAT)的实用性,我们利用GPAT反演确定了49次实际地震的震源机制、矩震级和震源深度.为了检验GPAT对地方地震、区域地震以及远震的实用性,我们选用了震级范围约为ML0.2~MS7.0之间的地震与震中距范围约在5~8000km之间的观测资料.对反演结果的分析表明,利用GPAT获取的震源机制结果在合理误差范围内是正确的,利用GPAT获取的矩震级结果是可靠的,而利用GPAT获取的震源深度总体上似乎比常规定位深度深约0.6km.总体而言,GPAT在震源机制、矩震级和震源深度的反演方面表现出良好的实用性.
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| 关 键 词： | 地方与区域地震 震源机制反演 广义极性振幅技术 实际震例 |
| 收稿时间： | 2015-04-28 |
An inversion technique for mechanisms of local and regional earthquakes: generalized polarity and amplitude technique (II): An application to real seismic events |
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| YAN Chuan,XU Li-Sheng,ZHANG Xu,LI Chun-Lai,XU Kang-Sheng.An inversion technique for mechanisms of local and regional earthquakes: generalized polarity and amplitude technique (II): An application to real seismic events[J].Chinese Journal of Geophysics,2015,58(10):3601-3614. |
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| Authors: | YAN Chuan XU Li-Sheng ZHANG Xu LI Chun-Lai XU Kang-Sheng |
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| Institution: | 1. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;
2. Gansu Earthquake Administration, Lanzhou 730000, China |
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| Abstract: | Determining focal mechanisms of small or micro-earthquakes is very important but difficult in seismological research, and no method has been commonly accepted and widely used due to complexity of this problem itself till now. In our previous paper we proposed an inversion technique, named generalized polarity and amplitude technique (GPAT), and the feasibility and capability of resisting disturbance of the technique has been tested with a series of numerical experiments. In this paper we present the examination of the practical ability of the GPAT by means of forty-nine real earthquakes.
The GPAT employs polarities of the P-wave first-motion and the maximal amplitude with polarities. The phases used here are generalized, which are no longer limited to well-known P-waves, S-waves or surface waves. The maximal amplitudes can be adopted as long as they are clearly recorded in spite of the well-known phases. GPAT uses the correlation coefficient between observed data and synthetic data as the objective function, and sets a weight factor for the first-motion polarities and the maximal amplitudes. In this paper we select forty-nine earthquakes with epicenter distances from 5 km to 8000 km, with magnitudes from ML0.2 to MS7.0, including six far-field events in and surrounding China, twelve regional events in Lushan, Sichuan, eight local events in Yingjiang and twenty-three local events in Qiaojia, Yunnan.
The focal mechanisms of the far-field events determined with GPAT are highly consistent with those from GCMT(Global Centroid Moment Tensor). The focal mechanisms of the regional events determined with GPAT are consistent with those from other studies, and they appear to be similar to each other. For the local events in Yingjiang, the focal mechanism of the main shock is consistent with those from other studies and other events have the mechanisms fairly similar to the main shock. For the local events in Qiaojia, they all have similar strike-slip mechanisms. Moreover, the moment magnitudes from the GPAT are reliable,but the focal depths from the GPAT seem to be about 0.6 km deeper than the routinely determined depths on average.
The GPAT is proved to have a good performance in the inversion for focal mechanism,moment magnitude and focal depth.It is not only suitable for far-field data, but also for regional and local data. It is not only suitable for moderate-size events, but also for small and micro events. |
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| Keywords: | Local and regional earthquakes Focal mechanism inversion Generalized polarity and amplitude technique Real earthquakes |
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