g e o d e s y a n d g e o d y n a m i c s 2 0 1 5 , v o l 6 n o 2 , 8 1 e9 0
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Earthquake prediction from China's mobile gravity data* Zhu Yiqinga,*, Liu Fanga, You Xinzhaob, Liang Weifenga, Zhao Yunfenga, Liu Liana a b
Second Crust Monitoring and Application Center, China Earthquake Administration, Xi'an 710054, China National Earthquake Infrastructure Service, Beijing 100036, China
article info
abstract
Article history:
The relation between plate tectonics and earthquake evolution is analyzed systematically
Received 4 November 2014
on the basis of 1998e2010 absolute and relative gravity data from the Crustal Movement
Accepted 7 January 2015
Observation Network of China. Most earthquakes originated in the plate boundary or
Available online 11 April 2015
within the fault zone. Tectonic deformation was most intense and exhibited discontinuity within the tectonically active fault zone because of the differential movement; the stress
Keywords:
accumulation produced an abrupt gravity change, which was further enhanced by the
Chinese mainland
earthquake. The gravity data from mainland China since 2000 obviously reflected five
Gravity change
major earthquakes (Ms > 7), all of which were better reflected than before 2000. Regional
Tectonic activity
gravity anomalies and a gravity gradient change were observed in the area around the
Seismic precursor
epicenter about 2 or 3 years before the earthquake occurred, suggesting that gravity change
Medium-term earthquake predic-
may be a seismic precursor. Furthermore, in this study, the medium-term predictions of
tion
the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes are analytically pre-
Crustal Movement Observation
sented and evaluated, especially to estimate location of earthquake.
Network of China (CMONC)
© 2015, Institute of Seismology, China Earthquake Administration, etc. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
1.
Introduction
The Crustal Movement Observation Network of China (CMONC) is an important scientific engineering infrastructure project that is implemented within the Ninth National Five-
Year Plan [1,2]. It includes a collection of gravity measurements that are important for seismic surveillance [3e8]. The Earth's surface gravity value depends on the location's latitude, altitude, and topography; tectonic deformation motion; and resulting crust's density changes [9e12]. The present
* This research was jointly funded by the Shanxi Science and Technology Plan Projects (2014K13-04) and the Special Earthquake Research Project Grant offered by the China Earthquake Administration (201508009) and the Crustal Movement Observation Network of China. * Corresponding author. E-mail address:
[email protected] (Zhu Y.). Peer review under responsibility of Institute of Seismology, China Earthquake Administration.
Production and Hosting by Elsevier on behalf of KeAi
http://dx.doi.org/10.1016/j.geog.2015.01.002 1674-9847/© 2015, Institute of Seismology, China Earthquake Administration, etc. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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study uses the Crustal Movement Observation Network's data to investigate the hypothesis that gravity observations can reveal earthquakes' focal mechanisms and enable medium-to short-term forecasting. The examined data exhibit clear mobile gravity anomalies near the epicenter prior to major earthquakes. Zhu et al. [6e8] made medium-term predictions of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes by analyzing these anomalies; the predictions are especially accurate in locating the epicenter. In the present study, through a detailed analysis of these case studies, the gravity spatiotemporal variations and the relations between continental crust activity and earthquake occurrence are investigated.
2.
Study area
The study area is situated on the intersection of the Circum-Pacific and Eurasian seismic belt of Chinese mainland. It is extruded by Pacific Plate and India Plate and Philippine Sea Plate and seismic faults develop there. China is one of the countries with serious earthquake disaster in the world and there have been six earthquakes with magnitude 7.0 since 21 century. To survey non-tide variation of gravity value in the mainland China and study the relation between the variation and local tectonic activity and seismic activity, regular repetition measurement gravity network has been built by China Earthquake Administration, which is made up of absolute gravity and relative gravity points and covers major tectonics on Chinese mainland.
3.
Methods
In data processing, we combine the absolute gravity observations with the mobile gravity observations for the same period, during which absolute gravity points provide a largescale, relatively stable, high-precision control network, and the mobile gravity observations act as a connective survey with this network, forming a dynamic monitoring network. This data-processing technique results in an initial benchmark for the gravitational field of the entire Chinese mainland. It can be effective at maintaining unity and stability, and it also provides rigorous and reliable solutions of the changes in gravity at the regional stations to obtain dynamic changes of the regional gravity field. During the processing of absolute gravity data, we made corrections for the earth's tides, light speed, local barometric pressure, polar motions, and vertical gradients. In the processing of relative gravity data, we corrected for the solid tide, barometric pressure, the first-order term, instrumental height, and periodic error. For data from 1998, we acquire dynamic change images of gravity field in multiple spatiotemporal scales. One kind of dynamic change images is from two measurements which were continuous in time in order to acquire differential information of dynamic evolvement of gravity field in different periods, such as gravity variations for 1998e2000, 2000e2002, 2002e2005, 2005e2008, and 2008e2010. Another kind is from two measurements that interval of two works is longer to
acquire accumulative information or background characteristic of gravity field between longer periods, such as gravity variation for 1998e2005 and 1998e2008.
4.
Gravity variation and high seismicity
Gravity variations between different time periods reflect crust deformation due to geodynamic processes, precursor to an earthquake occurrence (Figs. 1e7). The distribution of gravity variations between 1998 and 2000 is presented in Fig. 1. A general decreasing trend is observed from west to east. Gravity variation values reduce gradually from a maximum in the southeast coast (þ80 10 8 ms 2) to a minimum toward the QinghaieTibet Plateau ( 90 10 8 ms 2). The gravity data for this time period reflect variation preceding the Ms8.1 West Kunlun Mountain Pass earthquake in 2001, Ms7.2 Jilin-Wangqing earthquake in 2002, and Ms6.8 Jiashi earthquake in 2003. The seismogenic region of the 2001 West Kunlun Mountain Pass earthquake is placed in the northern part of the 90 10 8 ms 2 gravity variation contour. Northward, in the Tarim Basin, gravity values turn positive, diverging by up to 130 10 8 ms 2 The earthquake's epicenter is located in the intermediate area between the positive and negative values near the high-gradient zone [13]. The 2002 Ms7.2 JilinWangqing earthquake's epicenter is located within the increasing gravity-variation gradient zone, whereas the 2003 Ms6.8 Jiashi earthquake's epicenter is located at the highvalue gradient turning point [14]. In the subsequent years, i.e., 2000e2002, the gravity variation trend is reversed (Fig. 2); the change of gravity is gradually increasing from east to west, with the gravity variation value increasing from the southeast coast ( 10 10 8 ms 2) to the QinghaieTibet Plateau (60 10 8 ms 2). These gravity data reflect the situation after the Ms8.1 West Kunlun Mountain Pass earthquake. The earthquake zone in the eastesoutheast appears within the widespread positive change area. The Ms8.1 West Kunlun Mountain Pass earthquake occurred during the reversal period, when gravity change was strong in the Tibetan Plateau. Therefore, the relative reversal before and after the earthquake is possibly a co-seismic response. In 2002e2005, the overall gravity variation is positive, and it negatively changes from west to east, with highlighted regional variations. In the eastern part of China, two negative gravity-change regions are observed. The western part of China is divided into two gravity-change areas; smooth gravity changes are recorded north of the 36 parallel. In the south, gravity exhibits three significant change areas. These gravity variations reflect well the situation before the Ms7.3 Xinjiang Yutian earthquake in 2008, Ms6.9 Xizang Zegai earthquake in 2008, Ms6.8 Zhongba earthquake in 2008, and Ms8.0 Wenchuan earthquake in 2008. The Ms7.3 Xinjiang Yutian earthquake occurred within the high-gradient zone at the intersection between the West Kunlun fault and Altyn fault, corresponding to a gravity change from 50 10 8 ms 2 to 40 10 8 ms 2. The Ms6.9 Xizang Zegai earthquake and Ms6.8 Zhongba earthquake occurred from a positive to a negative anomaly within the gradient zone, west of Lasa. Finally, in relation to the Ms8.0 Wenchuan earthquake, a sharp
g e o d e s y a n d g e o d y n a m i c s 2 0 1 5 , v o l 6 n o 2 , 8 1 e9 0
Fig. 1 e Gravity value contours in the Chinese mainland from 1998 to 2000 (Unit: 10¡8 ms¡2).
Fig. 2 e Gravity value contours in the Chinese mainland from 2000 to 2002 (Unit: 10¡8 ms¡2).
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Fig. 3 e Gravity value contours in the Chinese mainland from 2002 to 2005 (Unit: 10¡8 ms¡2).
negative gravity change is recorded around SichuaneYunnan rhombic block around the SichuaneYunnan rhombus block; the earthquake occurred at the intersection between the high gravity-variation gradient zone and Longmenshan fracture. The gravity field exhibits the same overall trends from 2005 to 2008 (Fig. 4), gradually increasing from west to east and from the southeastern coast ( 80 10 8 ms 2) toward the QinghaieTibet Plateau (140 10 8 ms 2). In the east, the gravity pattern is somewhat even. In the west, it is more complex; there are three obvious gravity-change areas. The first area is located around the epicenter of the Ms8.0 Wenchuan earthquake, where gravity has a negative value of 120 10 8 ms 2, trending opposite than during 2000e2002 and 2002e2005; this area displays a strong reversed change. Qinghai Yushu and its vicinity comprise the second western gravity-change area, where the gravity variation is positive, up to 100 10 8 ms 2. Within this area, the Ms7.1 Yushu earthquake occurred at the intersection between the gravity-gradient zone and GanzieYushu fault in the south of the Balyanlkalla block [15]. Finally, the Ms7.3 Yutian earthquake occurred in the high-gradient gravity anomaly area. Between 2008 and 2010 (Fig. 5), gravity variation is positive and changes negatively from east to west in the Chinese mainland, exhibiting strong fluctuations. There are three gravity-change areas. First, gravity variation includes positive and negative changes in Xinjiang, which distribute in four quadrants in the east of Tianshan Mountain. The maximum
difference reaches up to more than 100 10 8 ms 2. The Ms6.6 Xinjiang Xinyuan and Hejing earthquake occurred in the center of the four quadrants, and it is sensitively reflected [5]. Second, gravity variation at the epicenter is greatly affected after the Wenchuan earthquake. In the south, differential gravity variation is more than 130 10 8 ms 2. The Ms7.0 Lushan earthquake occurred at the intersection between the gravity-gradient zone and Longmenshan fault, near the Wenchuan earthquake's epicenter; the Wenchuan earthquake possibly expedited the Ms7.0 Lushan earthquake [8]. Third, the recorded gravity variation is great after the Yushu earthquake, recovering after the previous period. Fig. 6 presents gravity changes from 1998 to 2005. Overall, the gravity field is gradually reduced from east to west, exhibiting a strong internal variability between þ70 10 8 ms 2 in the southeast coast and 60 10 8 ms 2 in QinghaieTibet Plateau. Three areas exhibit dramatic gravity changes in eastern China. First, in the southeast coast, large positive gravity changes and a high-gradient zone are recorded. Second, in the northeast, gravity-change anomalies extend over a large area, where the change alternates between positive and negative values, and the largest difference is by 80 10 8 ms 2; the high gravitychange gradient zone is observed in the Changchun-Qiqihar area. Third, in the Shanxi and Inner Mongolia area, there are gravity-change anomalies that reach 70 10 8 ms 2, and a high-gradient zone coincides with the juncture between Shanxi, Hebei, and Inner Mongolia.
g e o d e s y a n d g e o d y n a m i c s 2 0 1 5 , v o l 6 n o 2 , 8 1 e9 0
Fig. 4 e Gravity value contours in the Chinese mainland from 2005 to 2008 (Unit: 10¡8 ms¡2).
Fig. 5 e Gravity value contours in the Chinese mainland from 2008 to 2010 (Unit: 10¡8 ms¡2).
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Fig. 6 e Gravity value contours in the Chinese mainland from 1998 to 2005 (Unit: 10¡8 ms¡2).
In western China, gravity change presents two major characteristics. In the Sichuan and Yunnan areas, gravity change exhibits large-area positive and negative anomalies, where the difference reaches 110 10 8 ms 2. A high-gradient zone of gravity change exists in the LuzhoueWenchuaneMaerkang area. The 2008 Ms8.0 Wenchuan earthquake occurred at the intersection between the zero gravity contour and Longmenshan faults. Furthermore, in the juncture of Xinjiang and Tibet, where abuts Palestine, gravity change reaches 80 10 8 ms 2; positive and negative gravity changes are alternatively distributed in four quadrants, with the 2008 Ms7.3 Yutian earthquake occurring at the center. In the ten-year interval from 1998 to 2008, the gravity of mainland China regularly varies in the east-west direction between positive and negative values; the eastern patterns are always more smooth than the western ones (Fig. 7). In the west, there are four gravity anomalies that alternate from positive to negative values. A negative gravity anomaly is recorded in the western Sichuan plateau, where the minimum reaches 100 10 8 ms 2. There are positive gravity anomalies in the juncture between Qinghai and Tibet and in the eastern Tibet, with a maximum of þ80 10 8 ms 2, whereas there are negative gravity anomalies in the West Kunlun Mountain Pass. Finally, the positive gravity anomalies reach a maximum of þ140 10 8 ms 2 in the junction Xiinjiang and Tibet. Between 2001 and 2013, near these four gravity anomalies, five major earthquakes occurred: the Ms8.1 West Kunlun
Mountain Pass in 2001, Ms7.3 Yutian in 2008, Ms8.0 Wenchuan in 2008, Ms7.1 Yushu in 2010, and Ms7.0 Lushan in 2013.
5. Predicting earthquakes from gravitational anomalies Since 2000, five major earthquakes (Ms > 7.0) occurred in the Chinese mainland, all of which were preceded by well-reflected gravitational anomalies. Dispersive gravity data in Chinese mainland hadn't been calculated and analyzed in large measurement net when the Ms8.1 West Kunlun Mountain Pass earthquake occurred; thus, an image of the 1998e2000 gravity variations is not available for this region (Fig. 1). The China Earthquake Administration calculated the total gravitational field for February 2002, and a gravitational anomaly was indeed discovered prior to the earthquake (1998e2000, Fig. 1). Before the Yushu earthquake, the China Earthquake Administration also calculated the total gravitational field for February 2010 and discovered a significant gravitational anomaly near Yushu area (2005e2008, Fig. 4). The Bureau organized a seminar titled“Chinese mainland 7, 8 magnitude earthquake risk in medium-long term” at Chengdu, Sichuan Province. The conveners came to a consensus that gravity variations reached up to þ100 10 8 ms 2 in the east of the Tibetan border associated with a gravity-gradient zone and identified a risk of an Ms7.0 earthquake in the same
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Fig. 7 e Gravity value contours in the Chinese mainland from 1998 to 2008 (Unit: 10¡8 ms¡2).
area in the medium-long term. The obtained 1998e2010 mobile gravity data enabled the forecasting of three major earthquakes, which are evaluated herein.
5.1.
Prediction of the 2008 Ms7.3 Yutian earthquake
The timing of the Yutian earthquake was initially estimated in the medium term in the Gravity Research Report of the Annual Earthquake Tendency Conference, Second Crust Monitoring and Application Center (China Earthquake Administration, 2007). The prediction was as follows: Time: 2007e2008. Location: 36.0 N, 80.0 E, epicenter within a radius of 200 km. Magnitude: Ms6.0e7.0. On March 21, 2008, the Ms7.3 Yutian earthquake occurred at the predicted area; the estimated location is approximately 149 km from the actual epicenter, an accurate prediction considering the limited monitored area. During 2002e2005, gravity variation (Fig. 3) is greater in the borderland of Xinjiang and Xizang. The positive and negative anomaly areas differ by up to 100 10 8 ms 2, distributed in four quadrants. A gravity-gradient zone was formed at YutianeHetian in Xinjiang, consistent with the Kang XiwaeAltun fault strike slip. The high-gradient zone and gravity-variation shifting areas are formed by the Yutian earthquake [6].
5.2.
Prediction of the 2008 Ms8.0 Wenchuan earthquake
A medium-term prediction was also provided for the Wenchuan earthquake in the Gravity Research Report of the Annual Earthquake Tendency Conference (2007). The prediction was as follows: Time: 2007e2008. Location: 31.6 N, 103.7 E, epicenter within a radius of 200 km. Magnitude: Ms6.0e7.0. We clearly proposed that Wenchuan-Maerkang area should be paid attention to 6e7 earthquakes in research report of earthquake tendency conference in 2008. The Ms8.0 Wenchuan earthquake occurred on May 12, 2008 at the predicted area (31.0 N, 103.4 E), northeast of Wenchuan and between Yingxiu and Beichuan. The predicted location is approximately 72 km from the actual epicenter [7]. Gravity anomalies for the interval 2002e2005 (Fig. 3) are positive in the SichuaneYunnan rhombic block but negative around the block. Especially in the north of Sichuan, the variation is large, and a gradient zone is formed at ChengdueWenchuaneMaerkang. During the long period from 1998 to 2005, gravity changes further suggest that (Fig. 6) an increase in the extent and magnitude of positive gravity anomalies is in the inner area of the SichuaneYunnan rhombic block, whereas extensive negative gravity anomalies are recorded in the northern part of the block. Especially in
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northern Sichuan, the difference between the two anomaly areas reaches more than 100 10 8 ms 2, and a high gravitygradient zone exits in the LuzhoueWenchuaneMaerkang zone. The intersection of the zero line of the gradient zone and Longmenshan fault is the main criterion for predicting the earthquake's epicenter location [7].
5.3.
Prediction of the 2013 Ms7.0 Lushan earthquake
The Lushan earthquake was predicted in the medium term in the Gravity Research Report of the Annual Earthquake Tendency Conference (2013). In particular, the prediction was as follows: Time: 2013. Location: 30.2 N, 102.2 E, epicenter within a radius of 100 km. Magnitude: approximate Ms6.0. The Lushan Ms7.0 earthquake occurred on April 20, 2013 at the predicted area (30.2 N, 103.0 E). The predicted location is approximately 77 km from the actual epicenter. In addition to the Lushan earthquake prediction, the Chinese mainland gravity variation data also enabled the estimation of the gravity network of western Sichuan (Figs. 5 and 7). A highgradient zone and the identification of the gravity-variation shifting areas were the main criteria for location prediction for the Lushan earthquake [8].
5.4.
Evaluation of the earthquake predictions
The shape, magnitude, and duration of gravity anomalies correlate well with earthquake occurrence. Before a major earthquake (Ms > 5.0), there is always a strong and extensive gravity anomaly, which indicates the level and location of the regional stress accumulation and thus the magnitude, timing, and location of the upcoming earthquake. Based on the three examined predictions, an evaluation of the three predicted parameters of an earthquake, i.e., location, magnitude, and timing, is presented as follows. Regarding the location prediction, prior to the earthquake's occurrence, there is an extensive regional gravity anomaly in the gravity field and a local gravity anomaly near the epicenter, which is large in both range and magnitude and is related to the upcoming earthquake. A major earthquake occurs in the high-gradient zone, which is related to tectonic activity, and coincides with the juncture between the positive and negative gravity anomalies and the turning point of the gravity-change contours. The magnitude of an earthquake is correlated with the duration and extent of the gravity anomaly. Ordinarily, to accurately estimate the magnitude of an upcoming major earthquake, long time-period observational data is required. The magnitude is positively correlated with the extent, duration, and intensity of the gravity change. To analyze an earthquake-related gravity anomaly, recording the short- and long-term gravity changes is important. Gravity change becomes apparent for an earthquake of magnitude Ms ¼ 5.0 between two successive years' or even within the same year's gravity observations. This is often larger than 50 10 8 ms 2.
Strangely, gravity change does not appear to accumulate in the same manner beyond that; for Ms > 6.0 earthquakes, the gravity change is marked between two contiguous gravity observations, and for an interval longer than two years, the accumulative gravity variation is more marked than gravity variation from two continuous measurements. The variation is larger than 70 10 8 ms 2; especially for Ms > 7.0 earthquakes. For gravity data covering more than three years, the variation is larger than 100 10 8 ms 2. The relation between the time when an earthquake occurs and the timing of the gravity anomaly change may be explained as follows: in the time sequence, an earthquake occurs during the gravity field's inverse recovery, normally in about one year after the characteristic gravity change. The occurrence of a large earthquake, related to seismic tectonics, causes the rearrangement of stress in the underground medium, leading to the accelerative accumulation of nonlinear strain in the same medium, destabilizing faults, and then triggering the advanced occurrence of the next large earthquake. After Ms7.8 Pakistan earthquake in October 2005, because of the enhanced stress accumulation in the south of Xinjiang and the effects of the increased Indian-plate-induced northward compression, another large earthquake was triggered near the KangxiwaeAerjin faults involving violent gravity changes. In this respect, in 2006, a prediction of a major earthquake in the area within one or two years was presented, and the Ms7.3 Xinjiang Yutian earthquake on March 2008 confirmed the prediction.
5.5.
Gravity-change analysis
The preparation and development of an earthquake results from tectonic activity, mass migration, and density variations. All these processes cause gravity changes near the seismic area. On the basis of real data, many scholars have studied the mechanisms of gravity anomalies from several perspectives. The most popular theories to explain this phenomenon are as follows. According to the model of density change [16e18], regional stress-field changes create crust and focal medium density changes. The gravity measured at a surface observation point is a macro representation of the density below the same point. Alternatively, supporters of the expansion dilation and mass migration model perceive that the regional stress-field enhancement enlarges and perforates the fissions in the crust and causes mass upwelling in the deep crust or the upper mantle, thus altering the surface gravity field. The model of Moho deformation [11,19e22] dictates that the enhancement of regional stress or vertical force in the mantle leads to the deformation, elevation, and subsidence of the Moho boundary, resulting in longer wavelength surface gravity field changes. Finally, according to the model of fault dislocation and creeping [23e27], pre-earthquake creeping and coseismic dislocation of the faults cause gravity field changes on the ground. Our opinion is that regional stressfield change and pre-earthquake creeping together cause gravity change on ground. That is combination of two model of density change and fault dislocation and creeping can explain the gravity anomaly.
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6.
Conclusions
Mobile gravity measurements mainly reflect changes in the characteristic of the regional gravity field. The relation among density anomalies, tectonics, and earthquake occurrence is reflected in the results of mobile gravity repetition measurements. This study provides an insight to the relation between dynamic gravity change in mainland China and major seismic activity, as well as its application in medium-term earthquake prediction. Mobile gravity data prove extremely valuable for medium- and short-term earthquake monitoring and prediction. Nonetheless, earthquake prediction is a very complex problem. Despite the encouraging results provided by this study, the background gravity field characteristics should be further clarified to improve future earthquake predictions on the basis of gravity anomalies. From the viewpoint of the gravitational dynamic change, based on the analysis of the relation between variation characteristics and seismic activity presented in this study, the following may be concluded: 1) Seismic activity is closely related to spatial inhomogeneity and temporal discontinuity within the processes from stress accumulation to energy release. The stress accumulation at the focal area and the tectonic activity that alters the crust's density change the gravity field in this area prior to the earthquake's occurrence. 2) Major earthquakes occurred in the active fault zone of gravity variation. Tectonically active fault zones due to the differential movement and the intensity and discontinuity of the tectonic deformation contribute to changing gravity. The Ms8.1 West Kunlun Mountain Pass earthquake occurred in the east Kunlun fault zone, where gravity changed strongly. The Ms8.0 Wenchuan and Ms7.0 Lushan earthquakes occurred at the intersection of the gravity-gradient zone and Longmenshan fault. Finally, the Ms7.1 Yushu earthquake occurred at the intersection between the gravity-gradient zone and GanzieYushu fault. 3) Since 2000, Chinese mainland was inflicted by five major earthquakes (Ms > 7). Mobile gravity obviously changed, enabling the medium-term prediction of the Ms7.3 Yutian, Ms8.0 Wenchuan, and Ms7.0 Lushan earthquakes with great accuracy, especially with regard to the location of the epicenter.
Acknowledgments The authors would like to thank Enago (www.enago.cn) for the English language review.
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Zhu Yiqing, born in 1962, is a researcher and director of gravity at the Second Crust Monitoring and Application Center, China Earthquake Administratration. He graduated from Institute of Surveying in Wuhan in 1983. He is a member of Seismological Society of China Seismological bureau, and Earthquake prediction of China earthquake society of professional committee and crustal deformation measurement professional committee. He is mainly engaged in measurement and the theoretical and practical study of gravity. Up to now, more than 10 national research projects have been chaired or participated. He won 5 provincial-level scientific and technological progress awards, and personal by 5 times. As the first author or instructor, he has published more than 60 research papers, more than 10 papers of which were published in SCI/EI cited journals.
