Introduction: In theory, the observation objects and principles of strain seismograph and traditional pendulum seismograph are different, and the characteristics of observed signals should also be dissimilar. The observation results of pendulum seismograph show that seismic waves in inhomogeneous media will undergo refraction, reflection, and attenuation. Then, what signal characteristics can be detected by strain seismograph is great significance for understanding and explaining the observation results.Methods: Using YRY-4 type four-gauge borehole strainmeter as one kind of strain seismograph to detect the strain tensor change of the plane seismic wave emitted from the surface, a five-site strain seismograph observation network was built in Shanxi Province, with continuous observation for 2 years at a sampling rate of 100 Hz. In this paper, two local events occurring in the area covered by the strain seismograph observation network are taken as examples. We systematically studied the characteristics of seismic wave signals recorded by strain seismographs at five sites, inverted for the focal depth of the two local earthquakes and the relationship between the wave velocity and the wave velocity gradient of the focal depth, and calculated the apparent focal depth, the emergence angle and the take-off angle of seismic waves.Results: These results show stable uniqueness and apparent regularity, especially since the inverted focal depths are basically consistent with the seismic solutions based on those traditional pendulum seismographs. The observations from this study show that the strain seismograph can be used as an effective supplement to the pendulum seismograph.Discussion: In the future, we will continue to study the rupture process and focal mechanism of moderate-strong earthquakes and teleseismic earthquakes by combining two kinds of observations.

自2017年开始,陆续对中国地球物理台网10个钻孔应变测点的数据采集器进行升级,产出了大量的高采样钻孔应变观测数据.利用相关系数和自检精度2个检验四分量观测数据自洽性能的指标,定量分析了台站记录的2020年2月3日成都5.1级和2020年3月25日千岛群岛7.5级地震的应变地震波,结果显示高采样观测数据信度较高.对比分析了 10个台站记录的2次地震的震相,证明高采样四分量钻孔应变仪具备记录清晰应变地震波的能力,且其可靠性较高.综合结果证明,高采样四分量钻孔应变观测可进一步为地震学研究提供新的数据资源.

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.

我国地震地球物理观测台网中地电站网由92个地电阻率站点和111个地电场站点组成,地电数据集由地电阻率、地电场观测数据及相关产品构成,含我国地电站网在运行131个观测台站的原始观测数据、预处理数据和产品数据,并附带观测日志、基础信息等辅助信息,可为地震预测预报、地球动力学、电磁环境监测等多方面的科学研究提供强有力的数据支撑.

利用湟源台四分量钻孔应变观测的分钟值、1 sps、10 sps和100 sps四种不同采样率的观测数据,通过自检分析、同震应变阶分析和频谱分析等方法研究青海玛多M7.4地震同震变化特征.研究结果表明,分钟采样记录的地震波信息缺失严重,用分钟采样数据进行地震波初动、同震变化幅度等研究将会得到信度较低的结论;采样率越高,记录应变地震波信息的能力越强,但100 sps采样和10 sps采样结果相差不大,10 sps采样已能记录到比较全面的应变地震波信息;同震应变阶的变化性质和变化幅度与采样率无关;未来布设四分量钻孔应变仪时,建议应将采样率至少提高至1 sps.

Several different types of crustal deformation sensors have been deployed in mainland China and have produced a massive amount of crustal deformation data. By fusing the data from sensors with different frequencies, positions, depths, and precisions, the comprehensive characteristics of the overall regional deformation can be revealed. In this study, we used nearsurface and surface deformation sensors for Xinzhou area, Shanxi Province, China, which include a four-gauge borehole strainmeter (FGBS) and a global navigation satellite system (GNSS) receiver at different depths, respectively, to analyze the deformation in the study area. A joint analysis of the principal strain time series was conducted through strain conversion, and it was found that the study area is currently in a stable compressive state. It is concluded that GNSS and FGBS sensors can be deployed at the same station to facilitate the 3D observation and collaborative analysis of surface and shallow surface deformation.

The four-gauge borehole strainmeters (FGBSs) used in mainland China include multiple instrument modes.The sensors in the four directions have two layout modes in the vertical direction: the same-plane mode and the different-plane mode.In this study, we obtained a large amount of site observation data and showed that the observation data collected using the two modes have certain differences.Through the establishment of a 3D finite element model and field measurement analysis, it was concluded that the inhomogeneity of the coupling cement at different levels influenced the observations of the sensors in the different-plane mode, and the observation data were less self-consistent than those for instruments with sensors in the sameplane mode.The self-consistent characteristics of the FGBS provide an algorithm for AI-based seismic research.Comprehensive analysis showed that for the four sensors of the FGBS, the same-plane layout was the optimal choice.

基于地球物理数据跟踪分析成果,总结近年来我国地震地球物理台网观测环境干扰情况,分析环境干扰的时空分布特征,并介绍主要干扰及其典型形态特征.针对常见环境干扰,指出几种措施和方法,为干扰的抑制与排查提供参考.

殿沟泉气氡浓度在汶川地震后经常出现成簇高频震荡异常.应用数据挖掘方法,采用正规化、聚类、特征值计算等方法对氡观测数据和地震目录进行预处理,提取气氡异常、震级、震源深度和地震分区等参数,在此基础上采用贝叶斯网络模型开展殿沟泉氡异常与周边区域地震活动统计关系研究.利用聚类开展的地震分区结果显示与构造分区基本吻合,反映出不同构造单元地震活动的丛集性特征;贝叶斯网络模型结果表明泉点气氡异常与周边地震活动有关,特别是与汶川地震主震区龙门山断裂中段和临近区青川断裂区域的地震活动有关.研究结果有助于了解泉点气氡对周边地震响应的差异性特征,对未来该泉点气氡异常的判断与地震预测有参考意义.为地震前兆异常分析和地震活动分区提供了一种新的技术思路和方法.

四川省阿坝州理县蒲溪乡河坝村后山边坡属于老滑坡区,2014年6月以来,出现地表拉裂、鼓胀、下挫及挡墙剪切错断等现象,并不断加剧恶化,严重威胁当地民众安全.为预防滑坡灾害,当地政府在边坡前修建防护坝.为评估该防护工程效果,获取6个新建GNSS观测点实时变形观测数据,运用灰色关联法,明确降水变率是造成该区形变的主要因素,进而采用边坡变形量行业常用GM(1,1)模型,预测可能的边坡形变量,并与GNSS观测点实测值对比,结果表明,在防护坝建成1年7个月后,边坡变形速率逐渐减缓,防护工程治理效果显现.

介绍了地震地下流体台网概况、日常数据质量监控的流程与方法,总结了地震地下流体台网2017—2019年日常质量监控效果,以及在数据预处理、观测日志填写工作中出现的各种问题,并对典型问题进行了简要分析,旨在为监测人员的数据预处理和观测日志记录工作提供参考.

针对2021年5月22日青海玛多MS7.4地震,采用3种型号的钻孔应变仪观测到的应变资料对比分析同震应变波,结果表明3种仪器记录同震的初动时间、波动幅度和持续时间等存在一定差别:在震中距相当的情况下,TJ型体应变仪和RZB型四分量钻孔应变仪存在波动幅度变化小、持续时间短的问题,难以从背景变化中区分同震响应,影响钻孔仪器同震规律研究;YRY-4型四分量钻孔应变仪波动幅度变化大,持续时间长,在映震效果上表现较为突出.

地震前兆台网观测数据异常图像识别方法一直是地震监测预报人员研究的重要课题.为提高异常图像识别的工作效率,充分利用已有的异常图像识别经验知识,开展基于卷积神经网络(CNN)的快速异常识别方法探索性研究.结果表明:基于CNN的异常图像识别方法准确率较高,实现了异常图像的快速识别.整个台网的异常图像丰富多样,影响较多.由于特定观测手段下,特定影响因素的训练样本少,该方法应用于整个台网的异常图像的自动识别,还需要进一步开展研究工作.

以地下流体数据跟踪分析产出事件为研究对象,总结数据跟踪分析工作现状,从观测系统故障、自然环境、场地环境、人为干扰、地球物理、不明原因事件6个方面,分析2019年地下流体数据跟踪分析存在的问题,并对典型事件进行总结,为地震台站跟踪分析事件记录提供参考.

利用小波变换、相关分析、调和分析方法,分析仙游井水位在2017年7月打井抽水干扰前后各频带的变化特征.结果显示:打井抽水干扰严重时,水位的全频率影响显著;趋于稳定后中频带基本恢复,但低频带仍然存在多个强信号,M2潮汐应变响应能力略有下降,表明仙游井水位中频带在受干扰后是应力变化的有效监测波段.文章研究方法和结果可为水位资料干扰分析与异常提取提供参考.

随着地震数据跟踪分析工作的深入开展,发现环境干扰成为影响地球物理台网观测数据质量的主要因素之一,为此设计干扰源管理模块,为监测人员提供工作平台,对典型干扰信息进行有效管理.随着干扰源记录的不断补充,充实了干扰源数据库,可为今后干扰事件的大数据分析提供研究基础.利用该模块对干扰源进行管理,可有效提高地球物理台网数据质量,更好地为地震分析预报会商与台网运维管理服务.

The catastrophic Sanyanyu and Luojiayu debris flows, which were induced by heavy rain, struck Zhouqu County in Gannan Prefecture, Gansu Province, at approximately midnight, 7 August 2010 (Beijing time, UTC + 8), causing 1765 fatalities and huge economic loss. The ZHQ seismic station is located approximately 170 m west of the outlet of the Sanyanyu gully, and its power system was destroyed by the Sanyanyu debris flow when its leading edge reached the vicinity of the seismic station. In this paper, seismic signals recorded approximately 10 min before its termination are collected and analyzed to study the Sanyanyu debris flow. A double-exponential model is first proposed to quantitatively characterize seismic energy distributions in the frequency domain, which reveals that the peak frequency of seismic signals is around 5 Hz. Influenced by the Doppler effect, the peak frequency of the N–S component is the highest, and the U–D component is the lowest. Time–frequency analysis is applied to the seismic signals. From the spectrogram, it is easily observed that the formation time of the Sanyanyu debris flow is around 23:33:10. The entire debris flow is divided into three phases with distinct frequency characteristics, using 23:36:20 and 23:37:35 as crucial times. The frequency energy distributions in the first two phases are relatively stable, and are constrained in 0–8.8 Hz and 0–17.8 Hz, respectively. For the third phase, the upper boundary of frequency energy increases in a nearly linear manner, reaching approximately 35 Hz at the end. We calculate synthetic seismograms of the Sanyanyu debris flow. Generally, synthetic seismograms have morphological features and characteristics in key stages similar to those of the actual seismic records, and their maximum values are of the same magnitude. Our results suggest that the seismic source of a debris flow can be represented by a single-force model, and reveal that real-time monitoring and rapid identification of potential debris flows using broadband seismic network records is possible, which can provide approximately 15 min of pre-event warning for local residents and hopefully save many lives.

On August 7th, 2010, Sanyanyu and Luojiayu debris flows triggered by a heavy rain have lashed Zhouqu City around midnight, leading to catastrophic destruction which killed 1765 people and resulted in enormous economic loss. The ZHQ Seismic Station is located approximately 170 m west of the outlet of the Sanyanyu Gully. The seismometer deployed at the seismic station started recording seismic signals of ever-enlarging amplitude around 10 minutes before the debris flow rushed out of the Sanyanyu Gully, showing ever approaching seismic source, i.e. the debris flow. In this study, we analyze this seismic event and propose an inversion algorithm to estimate the velocity of the debris flow by searching the best-fitting pairs of envelopes in the synthetic seismograms and the corresponding field seismic records in a least-square sense. Inversion results reveal that, before rushing out of the outlet, the average velocity of the debris flow gradually increased from 6. 2 m/s to 7. 1 m/s and finally reached 15 m/s at approximately 0. 5 km above the outlet and kept this value since then. Obviously, the ever-increasing velocity of the debris flow is the key factor for the following disasters. Compared with other studies, our approach can provide the velocity distribution for the debris flow before its outbreak; Besides, it has the potential to provide technological support for a better understanding of the disaster process of a debris flow.

The observation error is derived from the pressure measurement,water density,and gravity acceleration error.The errors caused by the density and acceleration of gravity is related to the height of the water column.Error analysis results of the water density and gravity acceleration of the water level observation network in China show that the observation error caused by the error of water density and gravity acceleration can be ignored for most of the observation well.In order to reduce the measurement error of the instrument,the water level sensor should not be too deep,and water temperature in the observation well should not be too high.The influence of density cannot be ignored for observation wells with a high degree of mineralization and rich bubbles,and non-artesian wells with high water temperature.Finally,the testing situation of the water level instrument for many years is summarized.In the last few years the test method combining pressure input and simulation wells to test the observation error of net pressure type water level instrument is more scientific and precise.

观测数据的完整性对地震监测分析预报来说十分重要,关系到数据应用效能.观测系统故障是影响观测资料的完整性的主要因素.观测系统故障主要包括观测仪器主机故障,传感器故障、供电系统故障,通讯故障,井口装置故障,避雷装置故障等类型.本文结合数据异常跟踪分析工作,总结了2015年度地下流体台网观测系统故障,选取典型的观测系统事件进行分析,提出了处理措施与建议.