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| 1 | Movement and strain conditions of active blocks in the Chinese mainland显示文摘The definition of active block is given from the angles of crustal deformation and strain. The movement and strain parameters of active blocks are estimated according to the unified velocity field composed of the velocities at 1598 GPS stations obtained from GPS measurements carried out in the past years in the Chinese mainland and the surrounding areas. The movement and strain conditions of the blocks are analyzed. The active blocks in the Chinese mainland have a consistent E-trending movement component, but its N and S components are not consistent. The blocks in the western part have a consistent N-trending movement and the blocks in the eastern part have a consistent S-trending movement. In the area to the east of 90°E, that is the area from Himalayas block towards NE, the movement direction of the blocks rotates clockwisely and the movement rates of the blocks are different. Generally, the movement rate is large in the west and south and small in the east and north with a difference of 3 to 4 times between the rates in the west and east. The distributions of principal compressive strain directions of the blocks are also different. The principal strain of the blocks located to the west of 90oE is basically in the SN direction, the principal compressive strain of the blocks in the northeastern part of Qingzang plateau is roughly in the NE direction and the direction of principal compressive strain of the blocks in the southeastern part of Qingzang plateau rounds clockwisely the east end of Himalayas structure. In addition, the principal strain and shear strain rates of the blocks are also different. The Himalayas and Tianshan blocks have the largest principal compressive strain and the maximum shear strain rate. Then, Lhasa, Qiangtang, Southwest Yunnan (SW Yunnan), Qilian and Sichuan-Yunan (Chuan-Dian) blocks followed. The strain rate of the blocks in the eastern part is smaller. The estimation based on the stain condition indicates that Himalayas block is still the area with the most intensive tectonic activity and it shortens in the NS direction at the rate of 15.2±1.5 mm/a. Tianshan block ranks the second and it shortens in the NS direction at the rate of 10.1±0.9 mm/a. At present, the two blocks are still uprising. It can be seen from superficial strain that the Chinese mainland is predominated by superficial expansion. Almost the total area in the eastern part of the Chinese mainland is expanded, while in the western part, the superficial compression and expansion are alternatively distributed from the south to the north. In the Chinese mainland, most EW-trending or proximate EW-trending faults have the left-lateral or left-lateral strike-slip relative movements along both sides, and most NS-trending faults have the right-lateral or right-lateral strike-slip relative movements along both sides. According to the data from GPS measurements the left-lateral strike-slip rate is 4.8±1.3 mm/a in the central part of Altun fault and 9.8±2.2 mm/a on Xianshuihe fault. The movement of the fault along the block boundary has provided the condition for block movement, so the movements of the block and its boundary are consistent, but the movement levels of the blocks are different. The statistic results indicate that the relative movement between most blocks is quite significant, which proves that active blocks exist. Himalayas, Tianshan, Qiangtang and SW Yunnan blocks have the most intensive movement; China-Mongolia, China-Korea (China-Korea), Alxa and South China blocks are rather stable. The mutual action of India, Pacific and Philippine Sea plates versus Eurasia plate is the principal driving force to the block movement in the Chinese mainland. Under the NNE-trending intensive press from India plate, the crustal matter of Qingzang plateau moves to the NNE and NE directions, then is hindered by the blocks located in the northern, northeastern and eastern parts. The crustal matter moves towards the Indian Ocean by the southeastern part of the plateau. | LI Yanxing (李延兴) YANG Guohua (杨国华) LI Zhi (李 智) GUO Liangqian (郭良迁) HUANG Cheng (黄珹) ZHU Wenyao (朱文耀) FU Yang (符 养) WANG Qi (王 琪) JIANG Zaisen (江在森) WANG Min (王 敏) | 2003 | Science China Earth Sciences2003，46，z2： | 17 |
| 2 | Establishment of the GPS Monitoring Network in North China, the Relation of Horizontal Crustal Movement to Stress Field and Seismicity显示文摘In the paper, the establishment, measurement, data-processing program and monitoring accuracy of the GPS seismic monitoring network in North China, especially in the Capital-Circle area, have been presented briefly. The relation of horizontal crustal deformation to tectonic movement, stress-field variation and seismicity has been analyzed in detail. The results indicate that the accuracy of GPS measurement has reached the order of 10-9 and the annual rate of horizontal crustal deformation in North China is about 4 ~5 mm. Horizontal crustal movement is a direct indication of the regional stress field. Therefore, by monitoring the time-sequence variation of horizontal crustal motion, it would be possible to investigate the change in the stress field, to analyze the tendency of seismicity and to determine the seismogenic zones. | Li Yanxing, Hu Xinkang, Zhao Chengkun, Wang Min, Guo Liangqian, and Xu JushengFirst Crustal Deformation Monitoring Center, China Seismological Bureau, Tianjin 300180, China Institute of Seismology, China Seismological Bureau, Wuhan 430071, China | 1998 | Earthquake Research in China1998，12，4： | 1 |
| 3 | The CAS Bio-specimen Centers in Sound Progress显示文摘Bio-specimen centers, including herbaria and zoological museums, are the most integrated places for the storage of specimens, which are real samples and the most important vouchers for taxonomic and biodiversity studies. The information carried by | LI Liangqian QIAO Gexia YAO Yijian | 2010 | Bulletin of the Chinese Academy of Sciences2010，24，4： | 0 |
| 4 | Study on the Horizontal Deformation Strain Field in the Central and Northern Parts of Yunnan Province显示文摘Based on the horizontal deformation field and the strain field derived from the GPS data over the period of 1999~2001 in the Yunnan area, the characteristics of deformation and strain in the northern part of Yunnan Province have been studied. The results indicate that the central part of the studied area is rather stable with little crustal displacement, while the western and eastern parts are active with larger displacement. The strain field reveals that the orientations of the principal compressive strain axis of the crust and the sub blocks in the area are NW SE, while the orientations of the principal tensile strain axis is NE SW. In the studied area, the tensile strain is predominatly in the northern part and the compressive strain is predominatly in the central and southern parts. The stretching direction of the shear strain contour is basically consistent with the strike of the active fault. The strain and stress fields of the fault activity are related to the structure where the fault is located, while the activity properties of the faults are different. | Li Yanxing, Guo Liangqian and Zhang ZhongfuFirst Crustal Deformation Monitoring Center, CSB, Tianjin 300180, China | 2003 | Earthquake Research in China2003，17，1： | 0 |
| 5 | Removal of the rate table:MEMS gyrocompass with virtual maytagging显示文摘High-performance micro-electro-mechanical system(MEMS)gyrocompasses for north-finding systems have been very popular for decades.In this paper,a MEMS north-finding system(NFS)based on virtual maytagging(VM)is presented for the first time.In stark contrast to previous schemes of MEMS-based NFSs(e.g.,carouseling,maytagging)and the abandoning rate table,we developed a honeycomb disk resonator gyroscope(HDRG)and two commercial accelerometers for azimuth detection.Instead of the physical rotation of the integrated turntable in traditional NFSs,the vibratory working modes of the HDRG are rotated periodically with electronic control to reduce the uncertainty in the azimuth.After systematically analyzing the principle of NFSs with VM,we designed tests to verify the practicability at the sensor level.A bias instability of 0.0078°/h can be obtained during one day with VM in an HDRG.We also implemented comparative north-finding experiments to further check our strategy at the system level.The accuracy in the azimuth can reach 0.204°for 5 min at 28.2°latitude with VM and 0.172°with maytagging.The results show that without any mechanical turning parts,VM technology makes it possible to develop high-precision handheld MEMS NFSs. | Tongqiao Miao Qingsong Li Liangqian Chen Junjian Li Xiaoping Hu Xuezhong Wu Wenqi Wu Dingbang Xiao | 2023 | Microsystems & Nanoengineering2023，9，6： | 0 |
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