• Ma Xiaojing

      Articles written in Journal of Earth System Science

    • Tectonic stress accumulation in Bohai–Zhangjiakou Seismotectonic Zone based on 3D visco-elastic modelling

      Ju Wei Sun Weifeng Ma Xiaojing Jiang Hui

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      Future earthquake potential in the Bohai–Zhangjiakou Seismotectonic Zone (BZSZ) in North Chinadeserves close attention. Tectonic stress accumulation state is an important indicator for earthquakes;therefore, this study aims to analyse the stress accumulation state in the BZSZ via three-dimensionalvisco-elastic numerical modelling. The results reveal that the maximum shear stress in the BZSZ increasesgradually as the depth increases, and the stress range is wider in the lower layer. In the upper layer, themaximum shear stress is high in the Zhangjiakou area, whereas in the lower layer, relatively high valuesoccur in the Penglai–Yantai area, which may be affected by the depth of the Moho surface. Besides,weak fault zones will be easily fractured when the maximum shear stress is not sufficiently high due totheir low strengths, resulting in earthquakes. Therefore, based on the modelling results, the upper layerof the Zhangjiakou area and the lower layer of the Penglai–Yantai area in the BZSZ in North China aremore likely to experience earthquakes.

    • Tectonic stress pattern in the Chinese Mainland from the inversion of focal mechanism data

      Ju Wei Sun Weifeng Ma Xiaojing

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      The tectonic stress pattern in the Chinese Mainland and kinematic models have been subjected to much debate. In the past several decades, several tectonic stress maps have been figured out; however, they generally suffer a poor time control. In the present study, 421 focal mechanism data up to January 2010 were compiled from the Global/Harvard CMT catalogue, and 396 of them were grouped into 23 distinct regions in function of geographic proximity. Reduced stress tensors were obtained from formal stress inversion for each region. The results indicated that, in the Chinese Mainland, the directions of maximum principal stress were ∼NE–SW-trending in the northeastern region, ∼NEE–SWW-trending in the North China region, ∼N–S-trending in western Xinjiang, southern Tibet and the southern Yunnan region, ∼NNE–SSW-trending in the northern Tibet and Qinghai region, ∼NW–SE-trending in Gansu region, and ∼E–W-trending in the western Sichuan region. The average tectonic stress regime was strikeslip faulting (SS) in the eastern Chinese Mainland and northern Tibet region, normal faulting (NF) in the southern Tibet, western Xinjiang and Yunnan region, and thrust faulting (TF) in most regions of Xinjiang, Qinghai and Gansu. The results of the present study combined with GPS velocities in the Chinese Mainland supported and could provide new insights into previous tectonic models (e.g., the extrusion model). From the perspective of tectonics, the mutual actions among the Eurasian plate, Pacific plate and Indian plate caused the present-day tectonic stress field in the Chinese Mainland.

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