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GPS station short-term dynamic characteristics of micro displacement before Menyuan M6.4 earthquake

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Geodesy and Geodynamics 2016年第4期7卷 237-244页

作者： Wei Feng jinwei ren Zaisen Jiang Institute of Earthquake Science China Earthquake AdministrationBeijing 100036China China Earthquake Networks Center Beijing 100045China

Continuous observation data from 24 GPS stations are selected in the area （33.0°N-41.0°N, 95.0°E-105.0°E） for this study （the period is from Jan. 1, 2015 to Jan. 20, 2016）. Three components, NS, EW and UD, of the daily solutions are filtered by the Hilbert-Huang transform （HHT） with frequency band of 5.787×10^-7-7.716 ×10^-8 Hz （20-150 days in period）. And short-term dynamic characteristics of micro displacement before Menyuan M6.4 earthquake are studied by using the temporal dependencies and cross spectrum analysis. The results show that before the earthquake the horizontal undulatory motions are higher than the average level in the series data which indicate the disturbance feature of regional stress before the earthquake. Three GPS stations on Qinghai-Tibet Plateau with their setting perpendicular to the seismogenic fault have consistent movement. The increase of amplitude of the horizontal micro motion observed before the quake is conducive to the earthquake occurrence. However, we could not be sure if the undulatory motion triggered the earthquake. It is quite necessary to build more GPS continuous observation stations and optimize the monitoring network so as to improve the understanding of the shortterm dynamic crustal variation before earthquake.

关键词： Menyuan earthquake Global positioning system (GPS) Undulatory motion Hilbert-Huang transform (HHT) Cross spectrum

Precision estimation and geomorphological analysis based on the DEM generated by InSAR: Taking Damxung-Yangbajain area as an example

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Earthquake Science 2009年第3期22卷 263-269页

作者： Yaqiong Dai jinwei ren Xuhui Shen Jingfa Zhang Shunying Hong Institute of Earthquake Science China Earthquake Administration Beijing 100036 China Institute of Crustal Dynamics China Earthquake Administration Beijing 100085 China

Digital elevation model （DEM） can be generated by interferometric synthetic aperture radar （InSAR）. In this paper, the interferometric processing and analyses are carried out for Damxung-Yangbajain area in Tibet, using a pair of Europe remote-sensing satellite （ERS）-1/2 tandem SAR images acquired on 6 and 7 April 1996. A portion of the In- SAR-derived DEM is selected and compared with the 1：50 000 DEM to determine the precision of the InSAR-derived DEM. The comparison indicates that the root mean squared errors （RMSE）, which are used to evaluate error, are about 35, 60, 10, and 15 m in the studied area, mountainous area, basin area and near-fault area, respectively, suggesting that obvious errors are mainly in mountainous area. Besides, the limitation of InSAR technology to generate DEM is analyzed. Our investigation shows that InSAR is an effective tool in geodesy and an important complement to field surveying in some dangerous areas.

关键词： InSAR DEM geomorphological analysis Damxung-Yangbajain root mean squared error

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Earthquake Research in China 2005年第2期19卷 107-115页

作者： ren jinwei Institute of Earthquake Science China Earthquake Administration Beijing 100036 China State Key Laboratory of Earthquake Dynamics Institute of Geology CEA Beijing 100029 China

Plate motion is one of the major dynamic sources for deformation in the crust and the mantle. Since the deformation in the crust can be observed by GPS and geological observation, the comparison between the deformation of the crust and that of the mantle becomes one of the major methods available for studying the coupling between crust movement and mantle deformation. Regional crustal strain rate tensor values in China, inferred from Quaternary fault slip rates and earthquake deformation data within areas of approximately 200×200 km, are interpolated with smooth, continuous functions (spline) to determine a self-consistent model velocity gradient tensor field for the present-day Chinese continent. In the interpolation process, GPS velocity vectors are also matched, within a defined frame of reference, by the model velocity field. The directions of shear deformation calculated from the model velocity field are compared with the fast directions of shear-wave splitting inferred from SKS phases and Pn waves. The results might represent the shear deformation in mantle and the deep crust, respectively. There is a relatively large difference between the average direction of crustal shear and that of mantle shear in the area of active tectonics, which may indicate that in these active areas the crust and the mantle may be decoupled.

关键词： Crustal deformation GPS Lithosphere Anisotropy

Deformation Evolution Characteristics Revealed by GPS and Cross-fault Leveling Data before the M_S8. 0 Wenchuan Earthquake

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Earthquake Research in China 2019年第3期33卷 461-477页

作者： ZHAO Jing LIU Jie ren jinwei YUE Chong LI Jiaojiao State Key Laboratory of Earthquake Dynamics Institute of GeologyCEABeijing 100029China China Earthquake Networks Center Beijing 100045China Institute of Earthquake Forecasting CEABeijing 100036China China Aero Geophysical Survey and Remote Sensing Center for Natural Resources Beijing 100083China

Based on GPS velocity during 1999-2007,GPS baseline time series on large scale during1999-2008 and cross-fault leveling data during 1985-2008,the paper makes some analysis and discussion to study and summarize the movement,tectonic deformation and strain accumulation evolution characteristics of the Longmenshan fault and the surrounding area before the MS8. 0 Wenchuan earthquake,as well as the possible physical mechanism late in the seismic cycle of the Wenchuan earthquake. Multiple results indicate that:GPS velocity profiles show that obvious continuous deformation across the eastern Qinghai-Tibetan Plateau before the earthquake was distributed across a zone at least 500 km wide,while there was little deformation in Sichuan Basin and Longmenshan fault zone,which means that the eastern Qinghai-Tibetan Plateau provides energy accumulation for locked Longmenshan fault zone continuously. GPS strain rates show that the east-west compression deformation was larger in the northwest of the mid-northern segment of the Longmenshan fault zone,and deformation amplitude decreased gradually from far field to near fault zone,and there was little deformation in fault zone. The east-west compression deformation was significant surrounding the southwestern segment of the Longmenshan fault zone,and strain accumulation rate was larger than that of mid-northern *** locking indicates nearly whole Longmenshan fault was locked before the earthquake except the source of the earthquake which was weakly locked,and a 20 km width patch in southwestern segment between 12 km to 22. 5 km depth was in creeping state. GPS baseline time series in northeast direction on large scale became compressive generally from 2005 in the North-South Seismic Belt,which reflects that relative compression deformation enhances. The cross-fault leveling data show that annual vertical change rate and deformation trend accumulation rate in the Longmenshan fault zone were little,which indicates that vertical

关键词： MS8.0 Wenchuan earthquake GPS data Cross-fault leveling data Fault locking Block deformation

Deformation Model Inferred from Focal Mechanisms in the Chinese Mainland and Its Adjacent Areas

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Earthquake Research in China 2015年第2期29卷 145-157页

作者： Li Zhangjun ren jinwei Zhou Lin Qin Shanlan Chai Xuchao Second Monitoring and Application Center CEA Institute of Earthquake Science CEA

We collect seismic moment tensors of the earthquakes occurring from 1900 to 2013 in and around the Chinese mainland and summarize the surface ruptures and displacements of 70 earthquakes with M S≥7. 0. We divide these large earthquakes into three types. Type A contains earthquakes with surface ruptures and displacements. Type B is earthquakes without displacements and Type C is those without any of this data. We simulate a triangular distribution of displacements for Type B and C. Then,we segment these large earthquakes by using their displacements and surface ruptures. Finally,kinematic models are determined from earthquake data and Bicubic Bessel spline functions. The results show that,first of all,the reasonability and spatial consistency of defined models are *** rates have better continuity and are comparable with geologic and geodetic results in Himalaya thrust fault zones. The strain rates decrease in the Tarim basin and the Altun Tagh fault zones because of their low seismicity. The direction of compressional deformation in Gobi-Altay is changed from SE to NE and its extensional direction is changed from NE to NW. The extensional deformation in the Ordos block is diminished obviously. Secondly,earthquakes account for 30- 50% of expected motion of India relative to Eurasia determined from the NUVEL-1A model,with a missing component of 20 mm / a which may contain aseismic deformation such as fault creep and folds,the missing parts of earthquake data and elastic strain energy released by potential earthquakes.

关键词： Bicubic Bessel spline function Earthquake segmentation Kinematic modelSurface rupture

Uncovering the mysterious identity of Taisui——an old Chinese folk legend

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Science China(Life Sciences) 2020年第12期63卷 1942-1945页

作者： Erwei Li jinwei ren Qian Chen Hanxing Zhang Bin Lin Hui Zhang Shumin Zhang Xiaoling Zhang Lei Cai Xingzhong Liu State Key Laboratory of Mycology Institute of MicrobiologyChinese Academy of SciencesBeijing 100101China Department of Microbiology College of Life SciencesNankai UniversityTianjin 300071China Key Laboratory of Plant Molecular Physiology Institute of BotanyChinese Academy of SciencesBeijing 100093China State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China

Dear Editor,Taisui(太岁) has attracted great attention in China because it has been described in ancient Chinese texts as an entity possessing mysterious properties. In Chinese mythology and folklore, Jupiter is the God of the "Sui"(year) and is worshiped in Daoism. Jupiter appears at the same location in the sky approximately every 12 years(Jupiter’s orbit is11.86 years). However, since each cycle of Jupiter lasts for exactly 11.86 years and one Chinese year cycle comprises exactly 12 years, after approximately 84.7 years, Jupiter travels one cycle more than the number of cycles assumed by the ancient Chinese, which is called Taisui. According to the belief of the ancient Chinese, people are alerted when Taisui is digging in the ground, foretelling the destruction of houses or occurrence of natural disasters, such as floods and earthquakes(Zhao et al., 2018).

关键词： Jupiter floods cycle

Heterogeneous strain regime in the eastern margin of Tibetan Plateau and its tectonic implications

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Earthquake Science 2015年第1期28卷 1-10页

作者： Guojie Meng Xiaoning Su Weiwei Wu jinwei ren Yonglin Yang Jicang Wu Chieh-Hung Chen Nikolay V.Shestakov Division of Earthquake Deformation Institute of Earthquake ScienceChina Earthquake Administration Key Laboratory of Earthquake Prediction Institute of Earthquake ScienceChina Earthquake Administration Engineering Institute of Surveying and Mapping Earthquake Administration of Sichuan Province Tongji University ‘‘National’’ Chung Cheng University Institute of Applied Mathematics Far Eastern Branch of Russian Academy of Sciences

The eastern margin of Tibetan Plateau is one of the most active zones of tectonic deformation and seismicity in China. To monitor strain buildup and benefit seismic risk assessment, we constructed 14 survey-mode global position system （GPS） stations throughout the northwest of Longmenshan fault. A new GPS field over 1999-2011 is derived from measurements of the newly built and pre-existing stations in this region. Sequentially, two strain rate fields, one preceding and the other following the 2008 MwT.9 Wenchuan earthquake, are obtained using the Gausian weighting approach. Strain field over 1999-2007 shows distinct strain partitioning prior to the 2008 MwT.9 Wenchuan earthquake, with compression spreading over around Longmenshan area. Strain fieldderived from the two measurements in 2009 and 2011 shows that the area around Longmenshan continues to be under striking compression, as the pattern preceding the Wenchuan earthquake, implying a causative factor of the sequent of 2013 Mw6.7 Lushan earthquake. Our GPSderived dilatation shows that both the Wenchuan and Lushan earthquakes occurred within the domain of pro- nounced contraction. The GPS velocities demonstrate that the Longriba fault underwent slight motion with the faultnormal and -parallel rates at 1.0 -4- 2.5 mm and 0.3 4-2.2 mm/a; the Longmenshan fault displayed slow activity, with a fault-normal rate at 0.8 ± 2.5 mm/a, and a fault-parallel rate at 1.8 4- 1.7 mm/a. Longriba fault is on a par with Longmenshan fault in strain partitioning to accommodate the southeastward motion of eastern margin of the Tibetan Plateau. Integrated analysis of principal strain tensors, mean principal stress, and fast directions of mantle anisotropy shows that west of Sichuan is characterized as mechanically strong crust-mantle coupling.

关键词： GPS measurement Longmenshan faultzone Longriba fault zone Tectonic deformation TibetanPlateau

Application of Interferometric Spaceborne Synthetic Aperture Radar to Morphotectonic Research in the Bengcuo Area of Tibet

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Earthquake Research in China 2006年第4期20卷 460-468页

作者： Ning Shuzheng ren jinwei Shan Xinjian Tao Wei Zhou Dentin State Key Laboratory of Earthquake Dynamics Institute of Geology CEA Beijing 100029 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China China National Administration of Coal Geology Beijing 100039 China

Using ELLS-1/2 radar satellite data, we generated a Digital Elevation Model by Interferometric Synthetic Aperture Radar, and the ERS-1/2 DEM that we generated is obviously superior to both the 1/25 ten thousand-scale DEM of the National Fundamental Geographic Information System of China and the 90-m spatial resolution＇s SRTM DEM that America published in 2004 when it showed the characteristics of tiny structure relief. By analyzing the relief characteristics of the Bengcuo fault zone based on ERS-1/2 DEM, we find that the relief on the connection location of the Bengcuo and Pengcuo fault zones has complex characteristics. A structure relief that is similar to the Pengcuo fault zone crosses through the Dazi-Dasha fault on the the Bengcuo fault zone, while the Dazi-Dasha fault crosses through a gully at this place. This indicates that the Dazi-Dasha fault has been active at this place recently. At the same time, the Naka-Naduiduo fault is severed by the gully which was cut through by the Dazi-Dasha fault. Therefore, the Naka-Naduiduo fault was formed earlier than the Dazi-Dasha fault.

关键词： Interferometric Synthetic Aperture Radar Digital Elevation Model Strike-slipfault Pull-apart basin

The Characteristics of Time Series of Strong Earthquakes in the World and the Chinese Mainland

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Earthquake Research in China 2013年第3期27卷 301-315页

作者： Shao Zhigang Ma Zongjin Cai Jin'an ren jinwei Chen Huizhong Zhang Langping Institute of Earthquake Science China Earthquake Administration Institute of Geology China Earthquake Administration

Based on the strong earthquake catalogue, this paper discusses the characteristics of the time series of strong earthquake activities in the world, western Chinese mainland and its peripheral ＂big triangle seismic region＂, as well as the Chinese mainland. According to the analysis of the periodic features of global seismicity of M I〉 8. 0 strong events, it is found that there is significant difference in global seismicity before and after the 1960s. Statistical analysis with the Fisher method has revealed that the ＂big triangular seismic region＂ has experienced a process of M8.0 earthquake activity with a duration of over a hundred years since 1800. Further analysis shows that the global seismicity and the ＂big triangular seismic region＂ possibly has a period of a hundred-year scale, and has quasi- synchronicity to a certain extent. The shallow earthquake activity of Ms I〉 7. 0 in the Chinese mainland is obviously controlled by the seismicity in the big triangular seismic region and by global seismicity in a larger spatial-scale. In terms of the time series of these earthquakes, the seismicity shows a decadal and century-scale activity patterns.

关键词： Global Chinese mainland Strong earthquake activity