摘要The lithospheric magnetic field (LMF) in China and its surrounding are calculated using the spherical harmonic coefficients given by the NGDC-720 model. The LMF comes from the magnetization of minerals in the crust and in the uppermost mantle. It may, therefore, provide unique insight into lithospheric tectonic processes and mechanisms. Here, we study the geomagnetic manifestation of active tectonic blocks, and find a close correlation between the LMF and seismicity. Many large faults are found to closely overlap with magnetic anomalies, or are distributed along the boundaries of magnetic anomalies. Earthquakes in these fault regions have occurred on the boundaries of magnetic anomalies, or in the transition zones between positive and negative anomalies. We analyze the components of the LMF, and the LMFs at different altitudes, finding that the vertical component, Bz at 200 km, is the most related to seismic activity. Relevant physical mechanisms are also discussed. We propose that the stress or viscosity differences caused by temperature variations, which manifest in the LMF, may be the predominant reason for the correlation between the LMF and seismic activity along large faults.
Abstract：The lithospheric magnetic field (LMF) in China and its surrounding are calculated using the spherical harmonic coefficients given by the NGDC-720 model. The LMF comes from the magnetization of minerals in the crust and in the uppermost mantle. It may, therefore, provide unique insight into lithospheric tectonic processes and mechanisms. Here, we study the geomagnetic manifestation of active tectonic blocks, and find a close correlation between the LMF and seismicity. Many large faults are found to closely overlap with magnetic anomalies, or are distributed along the boundaries of magnetic anomalies. Earthquakes in these fault regions have occurred on the boundaries of magnetic anomalies, or in the transition zones between positive and negative anomalies. We analyze the components of the LMF, and the LMFs at different altitudes, finding that the vertical component, Bz at 200 km, is the most related to seismic activity. Relevant physical mechanisms are also discussed. We propose that the stress or viscosity differences caused by temperature variations, which manifest in the LMF, may be the predominant reason for the correlation between the LMF and seismic activity along large faults.
基金资助:the Seismic Industry- Specific (201108004). Liguo Jiao is also supported by the Central Research Institutes of Basic Research and Public Service Special at Institute of Geophysics, China Earthquake Administration (DQJB11B13), and National Nature Science Foundation of China (41174056, 41274079)
通讯作者:
Liguo Jiao
E-mail: lgjiao@cea-igp.ac.cn
引用本文:
Liguo Jiao, Huaran Chen, Mengtan Gao. Magnetic constraints on the spatial distribution of seismic activity[J]. 《地震学报》英文版, 2013, 26(2): 125-136.
Liguo Jiao, Huaran Chen, Mengtan Gao. Magnetic constraints on the spatial distribution of seismic activity. Earthquake Science, 2013, 26(2): 125-136.
