The WAG-H5-2 atom gravimeter is an upgraded version of the WAG-H5-1.Compared with previous work,a highly integrated and stable optical system has been developed for the new gravimeter,based on the principle of matter-wave interferometry.The Comparison of Absolute Gravimeters for the CMONOC(Crustal Movement Observation Network of China)project was organized by the China Earthquake Networks Center from January 30 to March 30,2026,in Wuhan.Our atom gravimeter(WAG-H5-2#2508)was invited to participate in this comparison.Absolute gravity at the indicated four sites was measured as requested by the organizer.Comparison results showed that no significant deviation existed between the WAG-H5-2#2508 atom gravimeter and laser interferometry absolute gravimeters,with deviations all within-4.3 to 6.1 μGal(1 μGal=10-8 m/s2).The performance of our instrument in terms of sensitivity,precision,repeatability,stability,and accuracy were evaluated.The WAG-H5-2#2508 exhibited a short-term sensitivity of 16.2 μGal/Hz1/2 and achieved an observation precision of～1.0 μGal over 1000 s.The measurement precision was better than 0.4 μGal,based on one-day observation data.The repeatability was approximately 1.5 μGal.Long-term gravity monitoring over half a month at a sampling interval of 88 s showed that the residual was within 10 μGal.The deviation of 1.4 μGal during the comparison represents the accuracy of the instrument compared with several other gravimeters(FG5X,A10,and IGG-03B).

This study focuses on the 2020 M5.9 Dingri earthquake in Tibet, which occurred within a monthly M5.5 ± 0.2 hazard zone predicted by the China Earthquake Administration using NOAA OLR data. It retrospectively examines OLR, tidal force, GRACE-FO gravity, and GPS data across a broad region (17°N–55°N, 72°E−135°E) covering the pre-, co-, and post-seismic phases. The earthquake occurred exclusively during the trough phase of cycle B among three regional tidal cycles (A, B, C). A unique, localized NE–SW oriented OLR anomaly appeared near the epicenter during this cycle, displaying a sequence—slight increase → increase → minor attenuation → increase → quiescence—consistent with the infrared emission stages of progressive rock fracture. GRACE gravity images (June 2019–May 2020) revealed significant local gravity changes spatially adjacent and morphologically similar to the OLR anomaly. The gravity anomaly showed pre-seismic enhancement and rapid post-seismic decay, preceding and outlasting the transient OLR change. This spatiotemporally coupled sequence indicates a transition from deep stress accumulation (gravity signal) to shallow crustal failure (OLR signal) at a critical threshold. Integrated GPS analysis suggests a causative mechanism: northward compression from the Indian Block induced stress accumulation southwest of the epicenter, evidenced by co-located gravity and OLR anomalies. As stress was transferred into the fragmented Tibetan Plateau, it transformed into near-east-west tensional stress. Tidal triggering then initiated a normal-faulting rupture along a near-north-south structure (marked by an OLR surge), culminating in the M5.9 event.

High precision surface gravity observation is one of the key means to study the internal deformation and material transport of the Earth. In the past decade, with the rapid development of modern precision geodetic observation technologies and the accumulation of high-precision gravity observation data on the surface, the application and research of absolute gravity observation in China's earthquake prevention and disaster reduction undertakings and the field of earth science have been deepened and expanded. This article mainly summarizes the application and research progress of absolute gravity observation in geodesy and geophysics in China, including the development of absolute gravity observation technologies (absolute gravity observation network, absolute gravity data processing), as well as the research progress of absolute gravity in earthquake monitoring (earthquake monitoring and prediction, calibration, and comparative observations of seismic gravity instruments) and geodynamics (crustal structural deformation, surface material migration, establishment and evaluation of gravity field models). Finally, some suggestions are proposed for development trends and application research directions of absolute gravity observation in terms of spatial resolution, gravity measurement network design, and new gravity observation technologies. With the gradual maturation of various types of independently developed absolute gravimeters in China, it is believed that absolute gravity observation will bring broader opportunities and prospects in application and research.

Since the 1975 MS7.3 Haicheng earthquake, spatio-temporal variations in the gravity field have attracted much attention as potential earthquake precursors. Recent technical advances in terrestrial gravity observation, along with the construction of a high-precision mobile gravity network covering Chinese mainland, have positioned temporal gravity variations (GVs) as an important tool for clarifying the signal characteristics and dynamic mechanisms of crustal sources. Reportedly, crustal mass transfer, which is affected by stress state and structural environment, alters the characteristics of the regional gravity field, thus serving as an indicator for locations of moderate to strong earthquakes and a seismology-independent predictor for regions at risk for strong earthquakes. Therefore, quantitatively tracking time-varying gravity is of paramount importance to enhance the effectiveness of earthquake prediction. In this study, we divided the areas effectively covered by the terrestrial mobile gravity network in the Sichuan-Yunnan region into small grids based on the latest observational data (since 2018) from the network. Next, we calculated the 1- and 3-year GVs and gravity gradient indicators (amplitude of analytic signal, AAS; total horizontal derivative, THD; and amplitude of vertical gradient, AVG) to quantitatively characterize variations in regional time-varying gravity field. Next, we assessed the effectiveness of gravity field variations in predicting earthquakes in the Sichuan-Yunnan region using Molchan diagrams constructed for gravity signals of 13 earthquakes (M ≥ 5.0; occurred between 2021 and 2024) within the terrestrial mobile gravity network. The results reveal a certain correspondence between gravity field variations and the locations of moderate and strong earthquakes in the Sichuan-Yunnan region. Furthermore, the 3-year AAS and AVG outperform the 3-year THD in predicting subsequent seismic events. Notably, the AAS and AVG showed large probability gains prior to the MS6.8 Luding earthquake, indicating their potential for earthquake prediction.

Relative gravimeters are widely used for monitoring the time-variable gravity signals, which are important for the investigation of various geophysical phenomena. Moreover, it is crucial to evaluate accurately the scale factors of the relative gravimeter, as any variations or uncertainties in the scale factor can lead to deviations from true gravity values, directly affecting measurement accuracy. In this article, we present a home-made cold atom gravimeter (CAG) named an atom gravimeter developed by the research team at Zhejiang University of Technology Model (ZAG) with high accuracy and stability, demonstrating its suitability for the precise calibration of relative gravimeters. A 64-day simultaneous and co-located observation with the ZAG and a gPhone relative gravimeter was conducted at the Beijing National Earth Observatory (NEOBJI) for evaluating the scale factor of the relative gravimeter. To address the long-term drift of the gPhone, both polynomial regression and Kalman filtering methods were applied before the scale factor was estimated. The estimated scale factor is 1.03017, with a relative evaluation precision of approximately 0.30 parts per thousand, determined by using the Kalman filter based on the gravity observation results from the ZAG as a reference. Additionally, the standard deviation of the residual signals over the 64-day gravity observation was calculated, yielding a value of 1.85 mu Gal. The results outperform the commonly used method of polynomial regression. These findings provide valuable insights for the high-precision calibration of relative gravimeters and improving the quality of long-term gravity observation data.

This paper addresses the challenges of traditional methods for calculating tidal gravity parameters,which are hindered by strict data format requirements,stringent parameter settings,and complex algorithms,making them difficult to adapt to modern large-scale gravity monitoring networks.We propose a new calculation method based on standard time-frequency transformation theory,which uses time-frequency spectral analysis tailored to gravity observation data.This method intuitively displays signal composition and variations,extracting tidal parameters.Simulation experiments and actual data processing at Korla Station demonstrate three advantages of our approach:(1)it intuitively reflects changes in the frequencies and amplitudes of tidal components over time,providing instantaneous values;(2)it utilizes the"Inaction method"(or"line-pass"filter)to directly extract harmonic signals from the spectrum,enhancing the intuitiveness of tidal analysis;(3)it employs direct methods for modeling solid Earth tides,calculating wave group amplitude factors and phase lags with accuracy comparable to the traditional Venedikov method,all without the need for strict data selection and parameter settings.

High-precision repeated absolute gravity observations conducted at the Luzhou observatory provide valuable insights into the processes of mass redistribution in the station's vicinity. In this study, we analyze four campaigns absolute measurements from two absolute gravimeters, FG5X-255 and FG5X-259, observed at the Luzhou gravity observatory and find a decrease in the gravity value of (− 93.3 ± 3.1) × 10 –8 m·s −2 from October 2020 to July 2022. By subtracting the contributions of vertical deformation, hydrological change, earthquake, and offset between instruments from the observation results, we derive a residual gravity change of (− 92.7 ± 4.1) × 10 –8 m·s −2 . Further analysis of field site photos and satellite images reveals that excavation related to the construction of a building near the Luzhou station is responsible for the observed gravity decrease. We use the load theory to calculate the gravity change at the Luzhou station due to the mass removal in the construction area and find that this factor could produce a gravity decrease consistent with the magnitude of the residual gravity change. Our results demonstrate that localized sources of mass redistribution, such as excavation at construction sites, can cause gravity variations exceeding 90 × 10 –8 m·s −2 nearby. Overall, our study highlights the importance of considering local mass redistribution when interpreting gravity variations.

The short-term effect of heavy rainfall on gPhone gravimeter observation at Zhengzhou Seismic Station is investigated. According to the observation data during Jul. 17–20, 2021, the corrected gravity residual reflects the gravimetric response caused by heavy rainfall. The observed gravity change is dominated by the local effect considering topographic effect on gravity. The deduced water depth near the observation station is about 300 mm.

文中推导并给出了基于非格网分布的起伏面扰动重力或重力异常解算区域扰动重力梯度场模型的数值计算公式.基于澳大利亚 West Arnhem Land 地区的格网重力数据,以频谱域(二维快速傅里叶变换)解算的扰动重力梯度全张量作为"基准值",然后利用基于推导公式的最小二乘配置方法(LSC)对相同区域非规则范围的重力数据进行扰动重力梯度模型解算,将结果作为"评估值".对比"基准值"与"评估值"之差,研究发现:1)基于推导公式的最小二乘配置方法解算得到的扰动重力梯度值与频谱域方法得到扰动梯度"基准值"各分量在空间形变变化上是一致的;2)统计扰动重力梯度各分量的差值 ΔδΓfft-lscxx、ΔδΓfft-lscxy、ΔδΓfft-lscxz、ΔδΓfft-lscyy、ΔδΓfft-lscyz 和 ΔΓfft-lsczz,"基准值"与"评估值"差值的标准差分别为 5.54E、5.30E、1.85E、6.55E、2.09E 和 9.67E(1 E=1×10-9s-2),远低于国际上实测重力梯度与解算模型差值的研究结果.最后,基于云南地区实测地表差分重力值,文中首次给出了该区域半波长约 20km的重力梯度场年际变化模型.文中的思路和方法提高了广泛分布的重力数据(主要为重力异常和扰动重力)的使用效率,可为地球物理学、地质学研究更好地理解和解释重力数据、重力梯度数据及其与场源的关系提供数据基础.

介绍了 2021年中国大陆构造环境监测网络(简称陆态网络)绝对重力比对观测的工作情况.基于各观测单位提交的数据,采用加权最小二乘平差方法,进行了统一的处理和分析,获得了各比测点位的标准参考值和各观测仪器的等效度.比测结果表明:8台绝对重力仪的等效度在-6.1～3.0 μGal之间,标准差RMS为2.8 μGal,基于归一化偏差进行判断,可见所有参加此次比测的仪器都是等效的,均可满足陆态网络项目要求.

利用覆盖九寨沟MS7.0地震的Sentinel-1升、降轨和Radarsat-2升轨数据,分别提取了3个轨道沿雷达视线向形变,运用多平台联合观测方法解算了九寨沟地震沿地表真实的垂直向、SN向和EW向形变信息.结果表明,3个轨道InSAR数据均监测到了LOS向同震形变,范围约55km×45km,呈"果仁状",靠近卫星飞行方向最大形变量为12.9cm(降轨),远离卫星飞行方向最大形变量为19.5cm(升轨).三维形变结果显示,垂直向上位移达23.4cm,垂直向下位移达17.6cm;北向位移达141.8cm,南向位移达100.2cm;东向位移达22.0cm,西向位移达10.7cm.树正断裂两端地块呈非对称水平相对运动,上盘单侧向东形变较剧烈,符合左旋走滑型地震事件的运动特征.

On 21 May 2021, an Mw 7.4 earthquake occurred in Maduo County, Qinghai Province, China. A dense network of high-rate (1 Hz) Global Navigation Satellite System (GNSS) stations around the epicenter provided one of the most complete recordings of GNSS kinematic displacements in Tibet to date. We used these data retrospectively to test a prototype earthquake early warning (EEW) system. Here, we present the results of that test, in which the EEW system archived high-rate GNSS displacement streams, and then used them to track evolving magnitude and slip. The geodetic module in the EEW system issued the first alert 34 s after the earthquake onset. The first alert had a moment magnitude (Mw) of 6.65, which then increased until reaching a stable value (Mw 7.4) 61 s after the earthquake onset. Testing results show good agreement with rapid GNSS displacements and postprocessed GNSS displacements; moreover, the rapid finite-fault inversion is consistent with postinversion magnitude and rupture dimensions. Our findings confirm the viability and usefulness of this EEW system in quasi-real-time magnitude estimation and finite-fault slip inversion.

利用重力台网进行台风激发信号的源区定位研究不仅有助于提高台风监测能力,而且可从台风激发信号中区分出震前与震源有关的信号,促进地震预测研究.以2019年第18号台风米娜(MITAG)为研究对象,基于福建省重力台网观测的1 Hz采样的固体潮观测数据,利用噪声互相关函数的信噪比(signal-to-noise ra-tio,SNR)和归一化噪声能量流方法分析数据质量和微震源区方位,使用SNR≥25的Rayleigh波互相关信号走时作为定位数据,进行台风4个时段的定位研究.结果表明,在MITAG台风靠近中国大陆的过程中,定位区域能够覆盖台风中心所在位置;地震背景噪声能量辐射模型的微震垂直位移极值区域也和台风靠近中国大陆过程时段一致;通过人工剔除高速波群的互相关信号后,定位区域也能覆盖到转向远离大陆过程时段的台风轨迹.福建省重力台网对台风的追踪提供一类新的数据和方法.

以中国大陆构造环境监测网络昆明台和恩施台gPhone相对重力仪连续重力潮汐观测数据为基础,研究了gPhone重力仪在1 mHz以上频段的高频响应.从瑞利面波角度获得gPhone重力仪的高频响应,并且通过与同址观测的STS-1地震仪LHZ分量数据进行对比,验证了gPhone重力仪高频观测结果的可靠性.对比从gPhone重力仪和STS-1地震仪观测数据中提取到的面波波形和群速度频散曲线,发现昆明台两类仪器观测到面波信号的振幅和相位都较为一致,而恩施台仅振幅较为一致,相位上存在较明显差异,gPhone重力仪记录的面波信号在各频段存在不同的时间延迟.用两类仪器观测数据获得了大地震激发的自由振荡,结果表明两类仪器观测到的基频球型模态自由振荡的频率和振幅都吻合较好,进一步验证了gPhone重力仪对高频频段信号振幅响应的可靠性.以上研究结果表明:利用gPhone重力仪能够准确地观测到大地震激发的面波和自由振荡等高频信号的振幅,但在记录信号的相位信息时,有些仪器会有相位偏移产生,如果研究中需要考虑信号的相位,则必须获得仪器相位偏移量,再进行仪器相位校正.

Multidisciplinary research shows the Red river fault zone’s (RRFZ) present movement and deformation state has complex segmentation feature. In order to further reveal its deep deformation mode, firstly, we extract tectonic movement gravity change information from mobile gravity measurement data by remove water storage varation and Vertical movement gravity effect; Secondly, together crust density interfaces model with gravity change information, then we can get the NMRFZ’s deformation mode of deep crust, which causes gravity variation.The average effect with a 50km radius is calculated for the recent gravity change rate in the Sichuan-Yunnan region, then the background rate field and the residual gravity change rate field are obtained. The trend of -0.66μGal/yr gravity-low-speed change in Sichuan-Yunnan region indicates that there is an inheritance between the gravity field and the uplifting background of the southeastern Tibetan Plateau. The crustal uplift is an important reason for the negative surface gravity changes, but it is mainly related to the deep tectonic environment. There are local positive change zones in the block boundary area, with obvious lateral extrusion and deep mass accumulation. It reflects that under the dynamic environment of the eastward flow of the Tibetan Plateau, the crust of north and middle-south section of the RRFZ are extruded and the underground mass become densification which make the surface gravity raising. The positive gravity changes in up-middle crust are more obvious than lower crust and Moho in Sichuan-Yunnan area. The RRFZ also exhibits a strong demarcation feature as a plate boundary, and the northern segment is the dividing line of gravity positive and negative changes area, while the middle-southern segment and its two sides also showed a wide range of positive change trends, with deep mass continue accumulation.The results of crustal deep deformation show that both the upper and the lower crust are obviously demarcated along the 101.5°E boundary, with the west side of the southwest Yunnan descending (moho: -0.05m/yr, upper-middle crust: -0.03m/yr) and east side of Sichuan-Yunnan block rising (moho ： 0.05m/yr，upper-middle crust： 0.02m/yr), which shows that the control effects in depth of the Kangdian crustal axis. The deformation rate of the deep crust in the RRFZ is the largest, the middle-south is next and the south the smallest. Gradual zone between the middle-south segment of the RRFZ and the Chuxiong-Jianshui fault zone shows strong activity and difference in the upper middle crust.

同震重力变化可为位错模型的检验和约束提供新数据.文中利用指数函数和阶跃函数法分析了玛多MS 7.4地震震中距≤800km的5个重力台的同震重力信号.结果显示:观测和位错模型模拟结果的方向一致性好,只是量级存在差异.通过对同震重力变化精度的讨论,同震重力变化和GNSS垂直位移的比较,九寨沟MS7.0、玛多MS7.4同震重力变化空间分布的分析,以及漾濞MS6.4地震对同震重力变化影响的改正,分析认为:震中距为175km的玛沁台记录到(2.9～4.0)×10-8m·s-2的同震重力变化;震中距为763km的中甸台在改正了漾濞地震的影响后记录到1.09×10-8m·s-2的同震重力变化;松潘台记录的9.1×10-8m·s-2的重力变化信号中应包含其他因素的影响;林芝台的负变化规律和位错模型模拟结果方向一致.综合文中的观测结果认为,玛多MS 7.4地震能够在175～800km的远场范围内产生约(0.5～4.0)×10-8m·s-2的同震重力变化信号.该结果可为未来中强地震远场产生的同震重力变化量级的判定提供参考.

In this paper, the flexural isostasy and gravity variations before the 2021 Madoi M(s)7. 4 earthquake were studied using the EIGEN6C4 Bouguer gravity anomalies, SIO V15. 1 topography model and the repeated gravimetry data. Firstly, based on the lithospheric flexural isostatic model, combining with Bouguer gravity anomalies and topography data, the effective elastic thickness (T-e) and the flexural isostatic gravity anomalies of the lithosphere in the epicenter and its surrounding area (northeastern Qinghai-Tibet Plateau) were calculated using the finite difference method. The results show that T-e ranges from 0 to 100 km in the northeastern Qinghai-Tibet Plateau, with obvious lateral changes and close relationship with block tectonic structures. To the north of the Bayan Har block, T-e of the Qaidam block is as high as 50 similar to 80 km, to the south, T-e of the Qiangtang block is larger than 20 km, with local high values larger than 30 km in the south of Wudaoliang and larger than 40 km around Yushu-Dege area. T-e of the Bayan Har block is 0 similar to 20 km, which is smaller than that of the north and south blocks, and it is more prone to deformation. Therefore, the mass in the Bayan Har block moves eastward under the north and south holding, and it is the primary area of eastward material flow in the central part of the Qinghai-Tibet Plateau. Earthquakes are prone to occur in the transition zones of lithospheric strength change (T, gradient zones) , as well as on the faults where T-e is low. The Madoi M(s)7. 4 earthquake occurred in the area with low T-e inside the Bayan Har block, with an effective elastic thickness of about 15 km near the epicenter. The analysis of repeated gravimetry data before the earthquake shows that the 3 similar to 5 years' accumulated gravity variations since 2015 present a regional change characteristic of negative-positive-negative from west to east, and a high gradient zone of gravity variation perpendicular to the fault zone is formed with the epicenter as the boundary, which mainly reflects the deep tectonic movement situation in the process of material flow from the Qinghai-Tibet Plateau to east before the earthquake. The gravity variations since 2018 is mainly characterized by a weak regional change from positive in the west to negative in the east around the epicenter, which shows that the epicenter area has been in the "solidification" state of high stress and strain, and the earthquake occurred at the turning point of the zero value line of gravity variations.

地震站网全流程一体化监控平台是基于微服务框架,应用数据库、通信、并行计算等传统信息技术,结合新兴的云计算、大数据进行建设的信息服务平台.该平台采用Hadoop分布式处理方案,应用Spring Cloud框架搭建,进行Docker容器封装,以标准RESTful API作为服务接口的微服务架构,实现了各应用服务模块之间的高内聚、低耦合及灵活、可扩展的特性,最终实现对地震台站运行的实时监测、高效运维和一体化管理.

本文介绍了中国大陆构造环境监测网络(陆态网络)2010～2018年4次绝对重力仪比测的成果,4期系统偏差最大值分别为3.5μGal、1.7μLGal、4.3μ.Gal和3.8μ.Gal(lμGal= 10-8m/s2),仪器互差分别为0～5.5μGal、0.3?3.2μ.Ga1、0～3.4μ.Ga1和1.1～7.0μ,Ga1.结果表明,参与比测的绝对重力仪观测中误差均优于5.0μGal,性能稳定,仪器间不存在明显的系统偏差,满足中国大陆构造环境监测网络绝对重力测量的工程设计要求.

重力潮汐观测在全球潮汐模型的建立、重力扰动信号识别等工作中具有重要作用,而潮汐观测精度是完成这些工作的基础.本文利用中国大陆构造环境监测网络10个重力站3年的重力固体潮数据计算了观测潮汐模型.在与历史已有结果进行比较后,分析了观测潮汐模型精度以及环境对精度的影响.结果表明,10个站观测潮汐模型的M2波潮汐因子中,误差最优为0.00014,主要潮波平均精度优于0.0010,高于20世纪80～90年代弹簧重力仪0.5～1个数量级,部分站点的精度可达早期超导重力仪水平,而与现代OSG型超导重力仪精度相差0.5～1.0个数量级.利用重力站中最优观测潮汐模型进行潮汐改正,潮汐改正精度指标(DRMS)可达±(0.2～0.3)x10-8m/s2,稍优于DDW/NHi 理论潮汐模型结果(±(0.3～0.6)x10-8m/s2).10个重力站均表现出了观测优于理论模型的特点.观测环境和场地的干扰会导致观测潮汐模型的精度下降,部分台站受环境变化和观测系统本身老化等不稳定因素干扰,其观测潮汐模型精度下降.DRMS 自(0.1～0.2)×10-8m/s2增至(1.0～1.7)×10-8m/s2.