Spatial-temporal characterization of the San Andreas Fault by fault-zone trapped waves at seismic experiment site,Parkfield,California

In this article,we review our previous research for spatial and temporal characterizations of the San Andreas Fault(SAF)at Parkfield,using the fault-zone trapped wave(FZTW)since the middle 1980s.Parkfield,California has been taken as a scientific seismic experimental site in the USA since the 1970s,and the SAF is the target fault to investigate earthquake physics and forecasting.More than ten types of field experiments(including seismic,geophysical,geochemical,geodetic and so on)have been carried out at this experimental site since then.In the fall of 2003,a pair of scientific wells were drilled at the San Andreas Fault Observatory at Depth(SAFOD)site;the main-hole(MH)passed a~200-m-wide low-velocity zone(LVZ)with highly fractured rocks of the SAF at a depth of~3.2 km below the wellhead on the ground level(Hickman et al.,2005;Zoback,2007;Lockner et al.,2011).Borehole seismographs were installed in the SAFOD MH in 2004,which were located within the LVZ of the fault at~3-km depth to probe the internal structure and physical properties of the SAF.On September 282004,a M6 earthquake occurred~15 km southeast of the town of Parkfield.The data recorded in the field experiments before and after the 2004 M6 earthquake provided a unique opportunity to monitor the co-mainshock damage and post-seismic heal of the SAF associated with this strong earthquake.This retrospective review of the results from a sequence of our previous experiments at the Parkfield SAF,California,will be valuable for other researchers who are carrying out seismic experiments at the active faults to develop the community seismic wave velocity models,the fault models and the earthquake forecasting models in global seismogenic regions.

China Seismic Experimental Site(CSES):A systems engineering perspective

China Seismic Experimental Site(CSES)deals with a long-term process of development of a multidisciplinary technical system.In the construction,maintenance,and upgrading of CSES,ideas of systems engineering play an important role.This article discusses several concepts which might be useful for CSES,including system metaphor,system performance evaluation,and system design.

China Seismic Experimental Site(CSES): Challenges of Deep Earth Exploration and Practice(DEEP)

Since May 2018,the planning,construction and functioning of China Seismic Experimental Site(CSES)has attracted much attention in earthquake science(CSES,2020 a,b,c;Wu,2020;Li et al.,2021).Different from traditional earthquake prediction experiment projects,such as the Parkfield earthquake prediction experiment(Roeloffs,2000).

An Analysis on the Experience and Routines of Experimental Site of New-countryside Construction of Xianhong in Hubei

The paper tends to make an empirical analysis on the experimental site of new countryside construction of Xianhong in Hubei, pointing out that the inner and outer dependence on routines of experimental construction. The paper also puts forward the beneficial policies, focusing on the agricultural production and fostering professional farmers, to reduce much dependence on routines.

Statement on the Tianshui Experimental Site of Soil and Water Conservation in 1940s

The Tianshui Experimental Site of Soil and Water Conservation was set up in 1942.Then the first construction publicized the thinking of soil and water conservation,and popularized the technologies of soil and water conservation and related plants.Their efforts established the foundation of the science of soil and water conservation with the first high-tech and high quality R&D team,and pushed the research of soil and water conservation building on the stage of systematization.All of this provided rare good scientific data and theoretical support for the soil and water conservation and the development of the regional economy in Northwest China.

Design and Site Experiment of Groyne in Bore Surging Area of Qiantang River

The groyne has been used widely in bank protection and river regulation. The plane layout and structural style of groyne are closely related to the stability of the groyne itself and the effect of bank protection. In this paper, based on the preliminary summary of the design of bank protection in the bore surging area of Qiantang River, some problems regarding the structure of groyne are pointed out and an improved plan is put forward. Site experiment was carried out combined with an emergency repair. The results of the experiment indicate that the improved project is reliable and successful.

Evaluation of Unknown Groundwater Contaminant Sources Characterization Efficiency under Hydrogeologic Uncertainty in an Experimental Aquifer Site by Utilizing Surrogate Models

Characterization of unknown groundwater contaminant sources is an important but difficult step in effective groundwater management. The difficulties arise mainly due to the time of contaminant detection which usually happens a long time after the start of contaminant source(s) activities. Usually, limited information is available which also can be erroneous. This study utilizes Self-Organizing Map (SOM) and Gaussian Process Regression (GPR) algorithms to develop surrogate models that can approximate the complex flow and transport processes in a contaminated aquifer. The important feature of these developed surrogate models is that unlike the previous methods, they can be applied independently of any linked optimization model solution for characterizing of unknown groundwater contaminant sources. The performance of the developed surrogate models is evaluated for source characterization in an experimental contaminated aquifer site within the heterogeneous sand aquifer, located at the Botany Basin, New South Wales, Australia. In this study, the measured contaminant concentrations and hydraulic conductivity values are assumed to contain random errors. Simulated responses of the aquifer to randomly specified contamination stresses as simulated by using a three-dimensional numerical simulation model are utilized for initial training of the surrogate models. The performance evaluation results obtained by using different surrogate models are also compared. The evaluation results demonstrate the different capabilities of the developed surrogate models. These capabilities lead to development of an efficient methodology for source characterization based on utilizing the trained and tested surrogate models in an inverse mode. The obtained results are satisfactory and show the potential applicability of the SOM and GPR-based surrogate models for unknown groundwater contaminant source characterization in an inverse mode.

Some Thoughts on the Earthquake Science Experimental Site——The Underground Cloud Map

The Western Yunnan Earthquake Predication Test Site set up jointly by the China Earthquake Administration,the National Science Foundation Commission of America,and United States Geological Survey has played an important role in development of early earthquake research work in China. Due to various objective reasons, most of the predicted targets in the earthquake prediction test site have not been achieved,and the development has been hindered. In recent years, the experiment site has been reconsidered,and renamed the "Earthquake Science Experimental Site". Combined with the current development of seismology and the practical needs of disaster prevention and mitigation,we propose adding the "Underground Cloud Map"as the new direction of the experimental site. Using highly repeatable, environmentally friendly and safe airgun sources,we could send constant seismic signals,which realizes continuous monitoring of subsurface velocity changes. Utilizing the high-resolution 3-D crustal structure from ambient noise tomography,we could obtain 4-D (3-D space+1-D time) images of subsurface structures, which we termed the "Underground Cloud Map". The"Underground Cloud Map" can reflect underground velocity and stress changes,providing new means for the earthquake monitoring forecast nationwide,which promotes the conversion of experience-based earthquake prediction to physics-based prediction.

中国地震科学实验场三维断层模型Web展示原型系统

活动断层的三维结构和模型是地震危险性研究的基础参数和重要数据。随着对接近真实形态的活动断层三维模型的应用需求不断增加,对这类模型数据的共享及研究的需求也日益增加。数据共享课题的一个重要议题是如何构建基于Web的三维断层模型展示平台,提高数据共享水平和用户体验。中国地震科学实验场(川滇地区)三维断层模型Web展示原型系统①是基于Arc GIS 10.6企业版的Web App Builder工具构建的一个实验性系统。该系统实现了基于Web GIS的三维展示系统的基本功能,并成功测试了更适用于地震行业标准的用户交互方式、基本功能、场景数据迁移方案和三维场景设计方案。场景数据从三维断层建模平台到GIS平台的迁移,是实现基于Web GIS三维展示系统的基础。场景中展示的三维数据采用与二维数据标准一致且视觉上融合度高的可视化方案。实践结果表明,三维数据从建模平台迁出后,应结合数据可视化方案,在属性层面上与二维数据相融合,以保证二维和三维数据在视觉上较好地融合。

岩溶山区坡面一孔多层地下水监测试验及科学意义

钻孔是揭露含水层结构和开展地下水监测的重要载体。在场地地下水监测中,不分层的丛式钻孔存在成本高、代表性不全等缺陷。“一孔多层”分层监测对水头或溶质分布的区分度高,在孔隙和裂隙含水层应用广泛,但岩溶介质因结构复杂,极少有案例研究。文章对丫吉试验场西坡径流小区的一个钻孔(ZK6)进行分层并开展监测。依据钻孔岩芯编录资料、抽水试验以及水化学与温度测孔的结果,判断岩溶发育的特征,确定将ZK6孔划分为四层,实施了钻孔封隔。对四个层位的水文观测发现,四个层位的水位动态对降雨的响应有较大差异。其中,第一层一个水文年中无水和充水状态时长分别占79%和21%,说明该层的岩溶介质处于充水和无水交替,且更多时间处于无水状态;第二层水位响应滞后明显;第三层和第四层水头差异表现出地下水排泄区的水头垂直分布特征。ZK6孔四个层位的水化学存在差异,表明岩溶介质结构的差异不仅影响了水文过程也影响水化学特征。第四层的电导率基本稳定在450μS·cm^(-1),而第二层因表层元素积累和水更新速率慢,电导率是第四层的2倍,第一层电导率的剧烈变化则反映表层岩溶带受到降雨补给影响最为强烈。综合钻孔分层的水文和水化学特征,认为第一至第四层分别代表表层岩溶带、裂隙基质带、上部饱水带和下部饱水带。岩溶山坡的“一孔多层”分层技术难度大,但一旦实现不仅可以认识岩溶垂向分带的水动力机制,也为地下水分层开发利用技术突破提供了可能。

川滇实验场地区活动地块边界新划分参考方案

活动地块边界带是现今地壳应力高度积累和构造变形显著集中的区域,地震频发,是研究中国内地强震活动规律的重要对象。中国地震科学实验场所在的川滇地区位于印度大陆与欧亚板块碰撞和持续会聚引起的强烈变形区,是中国内地西部与周边板块动力传递的关键部位。根据前人划分活动地块边界带的方案和依据,文中综合分析了地块的整体性、立体性、层次性和活动性,将川滇地区的主要活动断裂带划分为3条一级活动地块边界带和16条次级活动块体边界带。通过川滇地区有记录以来的强震分布特征、地震数量和震级的分带分级性、GNSS揭示的现今变形分区性、速度结构和重力资料反映的地壳深部构造差异性等结果,新的参考方案将金沙江-红河断裂带、甘孜-玉树-鲜水河-安宁河-则木河-小江断裂带、龙门山断裂带归为一级活动地块边界带;丽江-小金河断裂、南汀河断裂、龙日坝断裂等研究区内其他主要活动断裂归为次级活动块体边界带。基于对研究区强震活动、现今变形特征、活动断裂规模、地壳深部结构及古地震等研究成果的综合分析,研究认为一级边界带具备发生M≥7.5大地震的潜力,次级边界带有发生M≥6.5强震的能力。川滇地区活动地块边界新划分的参考方案,可为后续川滇实验场区活动地块之间相互作用的力学数值模拟、强震概率预测分析及大地震危险性评估等提供科学依据。

中国地震科学实验场BDS-3定位精度和地壳运动初步分析

我国BDS-3卫星导航系统于2020年7月建成,并为全球用户提供服务,自此开始,中国地震科学实验场(简称“实验场”)的GNSS测站相继接收BDS-3卫星数据,目前已经积累了2年多的观测数据,为BDS-3应用于川滇地区地壳运动监测提供了重要平台和数据保障。为评估实验场BDS-3观测数据的精度及其应用于地壳监测的可行性,本文首先根据各测站所记录的BDS-3的B1I和B3I两个频点的多路径效应和信噪比与卫星高度角之间的关系,对BDS-3的数据质量进行评价。然后,基于高精度数据处理软件GAMIT/GLOBK (10.7版)对各测站同期记录的BDS-3和GPS数据分别进行处理,得到BDS-3和GPS坐标时间序列。基于包括线性项、年周期项和半年周期项等分量的函数模型,利用极大似然法分别对BDS-3和GPS时间序列进行拟合估计,得到各测站的线性速度、年周期和半年周期信号,并对拟合结果对比分析,评定BDS-3和GPS的定位精度。最后,讨论BDS-3定位精度的影响因素和BDS-3水平速度场的区域性特征。研究表明:实验场BDS-3与GPS原始数据质量相当,BDS-3坐标时间序列的均方根残差(RMS)的平均值在N、E、U方向上分别为4.42、4.25和8.34 mm,稍大于GPS的结果。BDS-3与GPS速度场在E方向存在约2.0 mm/a系统性差异。在区域分布特征方面,BDS-3和GPS的速度场、周年期和半年信号没有明显差别。认为目前影响BDS-3定位精度的因素主要为卫星轨道产品不够完善,经验型太阳光压模型和卫星天线相位中心改正模型等欠缺。造成BDS-3和GPS速度场差异的原因主要为两者的定位基准不一致。随着实验场BDS-3观测数据的积累和数据解算模型的改进,BDS-3可望达到GPS的定位精度,并形成独立于GPS的监测系统,为该区地壳运动监测和地震预测提供优质的大地测量产品。

深埋软土盾构输水隧洞管片内力反演分析

依托滇中引水工程盾构隧洞监测试验环,于掘进方向进口和出口埋设两排混凝土应变计,同时埋设钢筋计作为对照组,对试验环的内力分布情况进行了现场试验监测。依据所获取的大量现场监测数据,分析了监测试验环混凝土应变与钢筋应变的误差、反演管片内力及其变化规律和内力安全性。结果表明,钢筋应变大于等于混凝土应变,受盾构机盾尾作用面的影响,进口处的钢筋应变与混凝土应变误差明显小于出口处;拱顶和拱底受较小正弯矩的作用,两侧受负弯矩作用,轴力值表现出持续的增长趋势且F块轴力明显大于其余块管片,F型管片部位整体性较差,是受力薄弱点,应尽量避免将F块布置到拱肩处;内力均在1.3的安全系数包络图内,表明该环结构适用于此处地质条件。

Three dimensional velocity model and its tectonic implications at China Seismic Experimental Site,eastern margin of the Tibetan Plateau

The China Seismic Experimental Site(CSES)is located at the intersection of the Tibetan Plateau,South China Block,and Indian Plate and has complex geological settings and intense crustal deformation,making it one of the most seismically active areas in Chinese mainland.A high-resolution,three-dimensional(3D)crust-mantle velocity structure is crucial for understanding seismotectonic environments,lithospheric deformation mechanisms,and deep dynamic processes.We first constructed a high-vertical-resolution 3D initial velocity model using the joint inversion of receiver functions and surface waves and then obtained a 3D P-and S-wave velocity model(CSES-VM1.0)with the highest lateral resolution of 0.25°for the CSES using double-difference tomography.Owing to the limitations of the Sn observation data,the resolution of the S-wave velocity model in the lower crust and upper mantle was reduced,making it closer to the initial model provided by joint inversion.A comparison with explosive-source seismic data showed that the synthetic P-wave first-arrival travel times of the new model were closer to the observations than those of the previous velocity models.The velocity cross-sections across the source areas of the 2022 Lushan MS6.1 and Ludian MS6.8 earthquakes reveal that the former earthquake occurred near a weak contact zone between the Tibetan Plateau and Sichuan Basin,and the rupture of the latter earthquake occurred in a granitic area,with the northern end blocked by rigid high-velocity bodies.A clear high-velocity anomaly zone is distributed along the western margin of the Yangtze Block,revealing the spatial distribution of Neoproterozoic intermediate-basic intrusions.This high-velocity zone significantly controls the morphology of fault zones and influences the rupture processes of major earthquakes.Two northeast-southwest and north-south trending high-velocity anomalies were found near Panzhihua,potentially related to Neoproterozoic and Middle-Late Permian intermediate-basic intrusions.The imaging results revealed the spatial distribution of the Lincang granitoid batholith,the uplifted zone of the central axis fault in the Simao Basin,and the Ailaoshan complex belt in the southwestern CSES,demonstrating a higher spatial resolution compared to previous results.Our velocity model provides an essential foundation for deep structural studies,high-precision earthquake locations,and strong ground motion simulations in the CSES.

山东某石化集团新建化验楼热管热回收系统能耗分析

实验场所为了排除废气通常要求的换气次数高,所需的排风量、新风量巨大,如果利用排风热回收装置回收排风中的冷热量,并用其对室外新风进行一定的预处理,不仅能提高室内空气品质,还可以达到节能经济和环保的双重目的。通过对山东某石化集团有限公司新建化验楼功能配套项目的通风系统进行设计,并配置热管余热回收系统对该通风系统的排风进行冷、热量回收,经过对热回收系统的能耗分析,得到该系统的热回收设备投资回收期不到两年,充分展现了在该化验楼中配置热回收系统具有显著的节能效益和经济效益。

云南场区宽频带地震监测台站勘选方法探讨——以文山和曲靖地区为例

地震监测台站勘选的合理性是决定地震观测数据质量、台站功能及稳定运行的重要因素。本文依据中国地震科学实验场建设工程项目云南场区宽频带地震监测意向台站的勘选要求,对云南文山、曲靖地区24个意向台站进行实地勘选,梳理总结了宽频带地震监测意向台站勘选的重要环节,可划分为室内资料收集、台址图勘、野外踏勘确定意向台址、场地协商及租地意向书签订、室内勘选资料整理5个阶段,其中台址图勘对野外踏勘确定意向台址起到了非常重要的作用,大大提高了意向台站勘选的工作效率。以CD151意向台站勘选为例,详细论述了5个阶段的工作方法;同时以4个意向台站噪声水平测试分析验证勘选方法的可行性,勘选的意向台站均符合Ⅰ级台基背景噪声水平,满足按照Ⅲ级地噪声台站勘选的观测环境技术要求,本研究对宽频带地震监测台站勘选工作具有一定参考价值和借鉴意义。

水-岩-气相互作用引起的水化学动态变化研究——以桂林岩溶试验场为例

利用多参数自动记录仪对桂林岩溶试验场的降水量、水位、水温、pH值和电导率进行了监测,数据采集间隔根据参数变化的程度由2min到1h不等。结果发现,岩溶裂隙水在洪水期间pH值呈降低趋势,而电导率呈升高的不寻常变化。与此相反,对于岩溶管道水,同样是在洪水期间,它的pH值是升高的,而电导率呈正常的降低。考虑到Ca2+和HCO-3分别为地下水中主要的阴阳离子(>90%),及它们与电导率的线性关系,计算得到了洪水期间方解石的饱和指数(SIc)和水的CO2分压(Pco2)的变化情况。发现洪水时裂隙水的Pco2高于正常情况的Pco2,而它的SIc值比正常情况低。与此相对,对于管道水,尽管同一洪水期间其SIc降低,但Pco2也降低。从这些结果,可以推断,至少有两个关键的过程控制着洪水期间的水化学变化。一个是雨水的稀释作用,另一个是水-岩-气的相互作用。然而,对于裂隙水来说,后者的作用可能更重要,即在洪水期间,高浓度的土壤CO2溶解于水中,则更具侵蚀性的水能溶解更多的石灰岩,从而增强水的电导率。而对于管道水,雨水的稀释作用更重要,因为研究区较高的pH和低电导率的雨水能更快地通过管道流出,所以,要了解岩溶系统水化学的变化,仅考虑水-岩相互作用是不够的,我们还必须重视CO2气体对岩溶系统中水化学变化的影响。总之。

温阳逐瘀汤对肾阳虚证大鼠急性脑缺血损伤后Wnt3a、β-catenin表达的影响

目的:观察温阳逐瘀汤对肾阳虚证大鼠急性脑缺血损伤后缺血脑组织无翅型MMTV整合位点家族成员3A(Wnt3a)、β-连环蛋白(β-catenin)表达的影响,并探讨温阳逐瘀汤防治肾阳虚证大鼠脑缺血损伤的作用机制。方法:将176只雄性SD大鼠分为空白组(Blank组,44只)和肾阳虚组(SYX组,132只);成功建立肾阳虚证大鼠模型后随机分为假手术组(Sham组,44只)、脑缺血模型组(MCAO组,44只)、温阳逐瘀汤组(WYZY组,44只)。WYZY组大鼠灌胃温阳逐瘀汤,MCAO组与Sham组灌胃等体积蒸馏水。各组在术后1 d,运用Zea Longa评分标准进行大鼠神经行为学评分,于术后3、7、14、21 d取材,每个时间选11只大鼠。苏木精-伊红(HE)染色观察神经细胞形态变化;运用酶联免疫吸附法(ELISA)检测各组大鼠血浆环磷酸腺苷(cAMP)、环磷酸鸟苷(cGMP)含量;免疫蛋白印迹法(Western Blot)检测缺血侧脑组织Wnt3a、β-catenin表达;实时荧光定量聚合酶链式反应(RT-PCR)检测Wnt3a、β-catenin mRNA表达。结果:与Blank组比较,SYX组cAMP含量下降(P<0.05)、cGMP含量升高(P<0.05)。HE染色结果显示,MCAO组细胞排列紊乱、大量细胞坏死、细胞膜消失、细胞核固缩,呈明显的脑缺血损伤表现;WYZY组前期细胞排列紊乱、部分细胞坏死,随着时间的延长,细胞损伤减轻,细胞排列逐渐密集,坏死细胞减少,脑缺血损伤显著改善。与MCAO组、Sham组比较,WYZY组cAMP含量升高,cGMP含量降低(P<0.05)。与MCAO组比较,WYZY组1、3、7、14、21 d神经行为学评分均降低(P<0.05)。与Blank组、Sham组比较,MCAO组、WYZY组缺血脑组织3、7、14、21 d Wnt3a、β-catenin表达均有增加(P<0.05);与MCAO组比较,WYZY组Wnt3a、β-catenin表达均增加(P<0.05),7 d Wnt3a达到峰值,14 dβ-catenin达到峰值。与Blank组、Sham组比较,MCAO组、WYZY组3、7、14、21 d Wnt3a、β-catenin mRNA表达均有增加(P<0.05);与MCAO组比较,WYZY组Wnt3a、β-catenin mRNA表达增加(P<0.05),7 d Wnt3a mRNA达到峰值,14 dβ-catenin mRNA达到峰值。结论:温阳逐瘀汤可改善肾阳虚证大鼠cAMP、cGMP水平及肾阳虚病理状态,可能通过上调Wnt3a、β-catenin表达减轻急性脑缺血损伤,减少神经功能缺损。

强矿震预测的研究

基于中尺度地震实验场高密度数字地震和潮汐形变台网的现场观测,用地震学方法和小波工具分析强矿震过程采集到的数据.发现震前短临阶段存在可信的b值、η值、频度等地震学异常和定点潮汐形变前兆异常.对异常信息的提取方法和强矿震短临阶段的预测进行了探讨.

探地雷达实验教学方法研究

探地雷达方法是工程与环境地球物理学的重要教学内容之一。为了提高实验教学质量、完善实验教学手段,在实验室内建设了大型实验砂槽,开展地下管线探测、地下结构物探测以及隧道衬砌质量检测模拟实验。实验中引导学生灵活运用学到的理论知识,达到理论联系实际的实验教学目的,拉近了理论教学与实际生产间的距离,训练了学生解决实际工程问题的能力,为学生今后开展探地雷达探测工作打下了基础。