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Pre-seismic and Co-seismic Crustal Movements of the M 7.3 Kyushu Earthquake on April 16,2016 in Japan

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Earthquake Research in China 2017年第4期31卷 589-600页

作者： Gu Guohua wang wuxing Institute of Earthquake Science China Earthquake AdministrationBeijing 100036China

The time series of coordinates of a large number of GPS stations in the world,processed by Prof. Geoffrey Blewitt with GIPSY software are available at http://geodesy. unr. *** on the time series of coordinates in the global reference frame of IGS08 at more than250 stations of continuous GPS observations,downloaded from the website,the co-seismic displacements of the M7. 3 Kyushu earthquake on April 16,2016 in Japan and the preseismic strain accumulations and displacements in the regional reference frame were obtained. The station of continuous GPS observation at BJFS near Beijing has been quite stable in displacement in the eastern part of China for more than 17 years since the beginning of its operation,and this station is used as the core station in the regional reference frame for the pre-seismic displacement of the Kyushu earthquake of M7. 3. The main feature of the pre-seismic displacements of the Kyushu earthquake is characterized by locking in the crust at and near the epicenter. The anomalous pre-seismic strain accumulation developed in an area of anomalous accumulation of the shear strain component of γ1 on the northeast side of the epicenter,with increasing size of the area and increasing magnitude in γ1. The largest area covered by the anomalous γ1 is about 2000 km2. The change in the E component at BJFS since November 26,2015 was caused by the replacement of the receiver and the antenna at the station. In order to study the shortterm change in displacements at stations at and near the epicenter,the time series at 3 stations with continuous GPS observations,2 at SUWN and DAEJ in south Korea and 1 at BJSH near Beijing were analyzed. The analysis shows that the displacements at the 3 stations have been quite stable in the same manner in east Asia. Thus,BJSH is used as the core station in the regional reference frame of displacement and the displacement time series show that there were no significant short term anomalies before the earthquake.

关键词： GPS GNSS co-seismic displacement 2016M7.3 Kyushu earthquake in Japan Earthquake precursor Earthquake prediction

Horizontal crustal movement before the great Wenchuan earthquake obtained from GPS observations in the regional network

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Earthquake Science 2009年第5期22卷 471-478页

作者： Guohua Gu wuxing wang Yueren Xu Wenjun Li Institute of Earthquake Science China Earthquake Administration Beijing 100036 China

The great Wenchuan earthquake of M8.0 on May 12, 2008, occurred in an area with dense GPS observation stations in the regional network of the Crustal Movement Observation Network of China （CMONOC）. Non-continuous observations were carried out at the 1 000 GPS stations of the regional network in 1999, 2001, 2004 and 2007. The horizontal displacements at GPS stations in the regional network before the Wenchuan earthquake show that the main driving tectonic force of the earthquake was the northward pushing of the Indian plate, added at the same time by the pushing of plates on the east and south. In comparison to the displacements in other regions, the horizontal displacements near and around the seismic area is characterized by diverging eastward displacements, that is, the stations to the north of the epicenter moved in the ENE direction while those to the south of epicenter moved in ESE direction with smaller displacements at stations near the epicenter. The accuracy of the estimated strain results is briefly discussed. In order to obtain the anomalous information before the earthquake, the methods of both best fits by trend surface and statistics have been used in the study for finding the future epicentral area from the strain accumulations in the regional network observed from 1999 to 2007 before the Wenchuan earthquake. Besides the epicentral area of the western Kunlun mountain pass earthquake of M8.1 in 2001, the results of best fits by trend surfaces of the strain accumulations from 1999 to 2007 in the regional network show that the Wenchuan earthquake occurred at the eastern fringe of a large area with relatively large accumulations of the first shear strains and also at the northeastern fringe of a smaller area with significant accumulated areal compressions. The statistics of the accumulations of the strain components demonstrates that they also showed anomalous distribution pattems in this area and its neighborhood with increasing accumulations of both she

关键词： Wenchuan earthquake horizontal crustal movement strain accumulation GPS earthquake prediction

Short-term and imminent geomagnetic anomalies of the Wenchuan M_S8.0 earthquake and exploration on earthquake forecast

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Earthquake Science 2009年第2期22卷 135-141页

作者： wuxing wang Jianhai Ding Surong Yu Yongxian Zhang Laboratory of Computational Geodynamics Graduate University of Chinese Academy of Sciences Beijing 100049 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China China Earthquake Networks Center China Earthquake Administration Beijing 100045 China

The diurnal variation of the geomagnetic vertical component is exhibited mainly by changes of phase and amplitude before strong earthquakes. Based on data recorded by the network of geomagnetic observatories in China for many years, the anomalous features of the appearance time of the minima of diurnal variations （i.e, low-point time） of the geo- magnetic vertical components and the variation of their spatial distribution （i.e, phenomena of low-point displacement） have been studied before the Wenchuan Ms8.0 earthquake. The strong aftershocks after two months＇ quiescence of M6 aftershocks of the Ms8.0 event were forecasted based on these studies. There are good correlativities between these geomagnetic anoma- lies and occurrences of earthquakes. It has been found that most earthquakes occur near the boundary line of sudden changes of the low-point time and generally within four days before or after the 27th or 41st day counting from the day of the appearance of the anomaly. In addition, the imminent anomalies in diurnal-variation amplitudes near the epicentral areas have also been studied before the Wenchuan earthquake.

关键词： geomagnetic low-point displacement diurnal-variation amplitude Wenchuan earthquake short-term and imminent geomagnetic anomaly forecast of strong earthquakes

Characteristics of coseismic water level changes at Tangshan well for the Wenchuan MS_8.0 earthquake and its larger aftershocks

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Earthquake Science 2009年第2期22卷 149-157页

作者： Baojun Yin Li Ma Huizhong Chen Jianping Huang Chaojun Zhang wuxing wang Institute of Geophysics China Earthquake Administration Beijing 100081 China Institute of Earthquake Science China Earthquake Administration Beijing 100036 China Earthquake Administration of Tangshan City Tangshan 063000 China Graduate University of Chinese Academy of Sciences Beijing 100049 China China Earthquake Networks Center China Earthquake Administration Beijing 100036 China

Coseismic water level changes which may have been induced by the Wenchuan Ms8.0 earthquake and its 15 larger aftershocks （Ms〉5.4） have been observed at Tangshan well. We analyze the correlation between coseismic parameters （maximum amplitude, duration, coseismic step and the time when the coseismic reach its maximum amplitude） and earthquake parameters （magnitude, well-epicenter distance and depth）, and then compare the time when the coseismic oscillation reaches its maximum amplitude with the seismogram from Douhe seismic station which is about 16.3 km away from Tangshan well. The analysis indicates that magnitude is the main factor influencing the induced coseismic water level changes, and that the well-epicenter distance and depth have less influence. Ms magnitude has the strongest correlation with the coseismic water level changes comparing to Mw and ML magnitudes. There exists strong correlation between the maximum amplitude, step size and the oscillation duration. The water level oscillation and step are both caused by dynamic strain sourcing from seismic waves. Most of the times when the oscillations reach their maximum amplitudes are between S and Rayleigh waves. The coseismic water level changes are due to the co-effect of seismic waves and hydro-geological environments.

关键词： Wenchuan Ms8.0 earthquake Tangshan well coseismic water level variation analog water level record

Advantages of GNSS in Monitoring Crustal Deformation for Detection of Precursors to Strong Earthquakes

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Positioning 2013年第1期4卷 11-19页

作者： Guohua Gu wuxing wang Institute of Earthquake Science China Earthquake Administration Beijing China

Earthquake predictions inChinahave had rare successes but suffered more tragic setbacks since the Xintai earthquake in 1966. They have developed with twists and turns under the influence of the viewpoint that earthquakes are unpredictable etc. Though the Wenchuan earthquake of M8.0 in2008 inChina and the 2011 Tohoku earthquake of M9.0 inJapan were failed to predict, the GPS observations before and after these 2 events have shown that there were precursors to these events and large earthquakes are predictable. Features of different observation techniques, data processing methods are compared and some recent studies on precursory crustal deformations are summarized, so various advantages of GPS technique in monitoring crustal deformation are emphasized. The facts show that anomalies or precursors detected from GPS observations before the great Wenchuan earthquake have been the most remarkable results of explorations on crustal movements and earthquake precursors in China. GPS is in deed an excellent observation technique for earthquake prediction.

关键词： Crustal Deformation Earthquake Prediction Precursor to Earthquake Wenchuan Earthquake Tohoku Earthquake in Japan GPS GNSS

Far-field crustal movements before and after the 2011 Ms9.0 Japan earthquake from GPS observations

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Geodesy and Geodynamics 2011年第3期2卷 1-7页

作者： Gu Guohua wang wuxing Institute of Earthquake Science China Earthquake Administration Beijing 100036 China

The paper gives an analysis of the displacement time series before and after the March 11,2011 Ms9.0 east Japan earthquake and co-seismic displacements observed at continuous GPS stations in and around China. The results showed a broad-scaled related elastic-rebound process and some premonitory horizontal crustal movements to this earthquake over this vast area.

关键词： Japan earthquake crustal movement GPS earthquake prediction co-seismic displacement

Preliminary Study on Simulation of Global Seismic Activities with Global Strain Rate

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Earthquake Research in China 2014年第2期28卷 164-176页

作者： wang wuxing Shi Yaolin Key Laboratory of Earthquake Prediction Institute of Earthquake ScienceCEA Laboratory of Computational Geodynamics University of the Chinese Academy of Sciences

The relationship between the strain rate field observed by GPS and global distribution of strong earthquakes is analyzed in this work. How do we recognize the characteristics of global seismic activities with space observation technology? A preliminary model of Cellular Automata that could simulate the global seismic activities both in time and space has been established based on the results of global strain rate field provided by the GSRM Program. The grid of the model is evenly divided,which is consistent with that of *** status of each cell is its strain state,and is adjusted according to the evolution *** shear strain criterion is adopted in the evolution of the Cellular Automata. The threshold for cells in surface expansion is 80% of that for those in compression. The preliminary model could in general simulate the main characteristics of the distribution of the global seismic activities. It could exhibit in general the global distribution of weak and active tectonic activities. Although the preliminary Cellular Automata model needs to be improved in many aspects,the result suggests the possibility of modeling the general features of rather complicated global seismic activities based on the strain rates obtained by GPS and other observations.

关键词： Global strain rate Cellular Automata Simulation Seismic activity

Anomalous crustal movements before great Wenchuan earthquake observed by GPS

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Geodesy and Geodynamics 2011年第2期2卷 13-22页

作者： Gu Guohua Meng Guojie wang wuxing Institute of Earthquake Science China Earthquake Administration Beijing 100036 China

Studies of GPS data carried out before and after the great Wenchuan earthquake of Ms8.0 on May 12, 2008 show that anomalous crustal movements occurred before the earthquake. Data from 4 pre-earthquake observation sessions at a dense network of stations show that there were prominent broad-ranged long- and midterm anomalies in horizontal displacements and strain and in vertical displacements. Data from the fewer-numbered reference stations of continuous GPS observations since 1999 in West and South China showed short-term preseismic anomalies in horizontal displacements. The detection of co-seismic horizontal displacements at these stations supports the existence of the pre-earthquake anomalies. Results of single-epoch solutions of data from continuous-observation stations near the epicenter also show large imminent anomalies in vertical displacements. Although the Wenchuan earthquake was not predicted, these results give a strong indication that GPS should be the main observation technique for long-term, mid-term, short-term and imminent earthquake predictions.

关键词： Wenchuan earthquake earthquake prediction GPS crustal movement, horizontal displace- ment vertical displacement

Dynamic Variations of the Gravity Field before and after the M5. 1 Wen’an Earthquake in Hebei Province

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Earthquake Research in China 2010年第1期24卷 22-30页

作者： wang wuxing Shi Yaolin Zhang Jing Shi Yanhua Institute of Earthquake Science China Earthquake Administration Beijing 100036 China Laboratory of Computational Geodynamics Graduate University of the Chinese Academy of Sciences Beijing 100049 China B aoding Observation Team of Earthquake Administration of Hebei Province Baoding 071000 China

In order to explore the abnormal variations before and after the Wen＇an MS. 1 earthquake on July 4, 2006, the gravity data observed by the Wenba Gravity Observation Network before and after the earthquake was analyzed. The relationships between gravity change and vertical displacement and shallow groundwater level were discussed, and elevation correction of the gravity was preliminarily performed. The results show that there were abnormal gravity changes before the MS. ! earthquake, which appeared as gravity rising in the whole observation network, especially in the south part. A high gradient of gravity variation appeared around the epicenter before the MS. 1 earthquake, especially during the short period between October 2005 to April 2006. The boundary of the positive and negative gravity variations gradually deflected and began to recover from October 2007.

关键词： Wen'an earthquake Wenba Gravity Observation Network Dynamic gravity change