宁波地震台2套水温仪同层观测互干扰现象

宁波地震台"九五"水温仪能灵敏记录到地震前兆异常变化,2010年4年2日"十五"水温仪安装,在ZK03井同一深度并行观测。并行观测期间,2套水温仪未记录到地震前兆明显异常变化,2015年4月24日"十五"水温仪探头因供电故障停运,"九五"水温仪恢复正常记录特性。分析认为,2套水温仪探头在运行状态下产生相互干扰,从而无法记录到地震前兆异常变化。因此,小孔径、小流量观测井不宜进行水温同层平行观测。     

张道口地震台水物理测项干扰分析

地震前兆台网观测数据跟踪分析是地震预报的重要基础,对观测数据干扰进行分析排除是提取地震前兆信息的核心。通过对张道口地震台2015～2018年水物理观测数据受干扰情况分析,及时发现和总结观测数据存在的各种问题,将干扰分为人为干扰、系统干扰、自然干扰、场地环境4种类型,并将6种具体干扰分别归纳到了相应的干扰类型,找出了干扰的特征,描述了干扰的过程,分析了引起干扰的具体原因,阐释了干扰对水温水位前兆数据观测造成的影响,并对干扰的过程进行了相关的验证,提出了避免干扰的技术措施。通过对水位水温干扰全方位的分析研究,能够促进对地震前兆信息的处理,以期快速准确地识别并排除前兆干扰,为全国其它地震台水位水温干扰分析提供一定的科学依据和技术支持,夯实通过水物理测项预报地震的基础。     

聊城地震水化站水温奇异变化原因的调查与研究

聊城地震水化站水温观测井于2008年8月出现奇异变化,水温大幅度指数型下降。作者在收集分析井区-水文地质背景条件的基础上,调查研究了奇异变化的可靠性、产生的原因及作为地震前兆异常的可能性。结果表明,奇异变化可能是井管老化微裂,导致新的低温含水层中地下水渗入井内而引起的,作为地震前兆异常的可能性很小。     

青海地区井水温度(地温)的数字化观测及地震前兆监测效能评估

较为系统的分析了青海地区"十五"期间架设的12个数字化水温(地温)井的观测现状,及年、月、日不同层次上的动态特征,对其在相关的地震前兆观测中发挥效能的可能性作了宏观的评估。结果表明,有10个井孔可在地震中期前兆监测中发挥效能,有7个井孔可在地震短期的前兆监测中发挥效能,有7个井孔可在地震短临前兆监测中发挥效能。文中还介绍了主要影响数字化水温(地温)资料的干扰因素。     

景东井水温异常变化与地震关系初探

系统分析景东观测井1998年以来的水温观测数据,研究水温前兆异常与地震之间的对应关系。结果表明,该井水源补给可能来自深部,水温变化不受季节性降雨渗入影响;震前异常全部为短期异常,以高温异常为主,短临异常突出,地震对应率50%,低温异常地震对应率80%;水温异常对发生在红河断裂和澜沧江断裂之间的地震指示意义最好,使用资料时考虑区域构造特点能很好地提高单个观测点的地震监视能力。     

金沙江水网及其地震地下水前兆监测能力的讨论

金沙江下游梯级水电站水库地震地下水动态监测网(简称金沙江水网),是中国第2个专门用于水库区地震前兆监测与研究为目的的企业地下水动态监测网.文中简要介绍了该网的布设、观测网的技术构成、观测井与观测含水层的基本特征及试运行的基本结果,从观测井-含水层特征及观测到的水位与水温多月、月、日动态特征,评估了其地震前兆监测能力.     

增城地震前兆数字化综合观测试验台顺利通过验收

为改变广州市地震前兆观测落后局面而进行的“深孔钻井进行地震前兆综合观测方法的可行性研究”项目 ,日前顺利通过由广州市科技局主持的专家验收。广州市地震前兆观测技术 ,长期以来处于近乎空白的状态 ,目前只有花都有两口井在正常运行 ,观测项目也只有水位、水温 ,而且记录的是模拟数据。为此 ,广州市政府地震办公室提出对“深孔钻井进行地震前兆综合观测方法”的可行性研究 ,得到广州市科技局大力支持并列入广州市 2 0 0 1年度科技计划项目中。经过近一年的工作 ,在完成“可行性研究”的基础上同时开展增城地震前兆数字化综合观测试验台…     

京津冀地区井水温度的数字化观测及其地震前兆监测效能的评估

较为系统的分析了北京、 天津、 河北地区井水温度观测现状及年、 月、 日不同层次上的动态特征, 及其在相关的地震前兆监测中发挥效能的可能性做了宏观的评估。 评估结果表明, 74.7%井的水温观测正常运行, 58.6%的井在地震中期或中短期的前兆监测发挥效能, 67.8%的井在地震短期前兆监测发挥效能, 41.2%的井在地震短临前兆监测中有可能发挥一定效能。 文中还提出了进一步发挥井水温度观测监测效能的若干建议。     

内蒙古赤峰市金厂沟梁镇中学水温上升变化的调查分析

井水温度观测是一项重要的地震前兆观测手段,旨在捕捉地震孕育过程中的应力-应变信息。井水温度的同震响应就是很好的例子,因此水温作为地壳应力-应变信息的真实反应和地震前兆判断依据,具有重要的研究意义。通过内蒙古赤峰市金厂沟梁镇中学水温升高事件调查与研究,简单分析该事件与地壳应力变化的关系。     

西南地区地震观测井泉水温动态特征研究

本文利用西南地区地震前兆台网记录的井泉水温数字观测资料,对水温各类动态特征进行研究,提取不同井水温各类观测动态及同井不同深度水温各类观测动态特征.收集整理了114个井泉水温观测台站的观测数据,结果表明,西南地区水温观测以中深非自流井为主,水温动态范围较大,热水和高温热水主要分布在川西和云南地区.西南井泉水温长期动态可大致分上升型、下降型和波动型三种,短期动态可大致分为短周期型、稳定型、固体潮型三种.研究区井水温的同震变化以下降居多,单个井水温对不同地震的同震响应存在优势响应方向,说明水温的同震特征更依赖于井孔自身观测条件的影响.通过对1966年以来西南地区36次MS≥5.9级震例总结的统计分析得出,西南地区水温前兆异常率达67％,上升型水温异常占比最大,且水温异常多属于短临异常.给出了Ms≥5.9地震震前水温异常井的最大震中距的大致范围,并根据异常震中距-震级的G-R关系给出其定量关系,为今后西南地区中强地震的发生提取有用的水温前兆信息提供基础资料.     

同井不同层位水温观测同震变化机理分析

不同水温观测点由于观测环境、井孔条件、观测部位构造条件、介质条件、地下水动力条件的差异,使得水温动态呈现出不同的形态。而同一观测井内不同层位的水温由于水温传感器安置深度和井孔热源分布状态的不同,会出现不同的同震响应形态。利用小波变换算法,分析了房县三海村井不同深度的水温在3次地震中的同震响应变化,并结合该井的温度梯度、围岩特性以及含水层分布,提出一个简单的井-含水层模型。进而探讨了同井不同层位水温出现不同变化的动力学机制,初步认为其动力学机制源于水的流动产生的热对流引起的变化。     

甘肃地区水氡(流量)异常与周边中强地震的关系探讨

甘肃及周边地区是一个中强震多发区,该地区的前兆异常对青藏高原北缘地区强震活动有着敏感的反映.1980年以来该区发生5.0级以上地震20余次.多次地震前,甘肃地区的水氡资料出现了大量的中短期异常.分析了甘肃省目前仍在继续观测、观测环境较好、仪器稳定的水氡测点在甘肃及周边地区发生的中强地震前资料的变化情况,发现多数测点在多...     

荣成鲁32井水温动态变化及异常分析

总结了鲁32井水温正常动态特征以及自然环境干扰形态特征,探究鲁32井水温异常变化特征,通过对该井周围500km范围内中等地震及远场大震发生时间、空间与水温异常时段对比,发现两者对应关系良好,综合分析已有数据资料认为,鲁32井水温存在附加地热场异常变化的构造条件,可作为近场中等地震前兆异常和远场大震前兆异常中短期判别指标之一。     

青海玉树与德令哈地热观测井在汶川与玉树地震前的异常特征

本文较为系统地分析了青海省玉树与德令哈二口地热观测井自2007年以来的水温观测数据,发现这两口井对2008年5月12日四川汶川M_S8.0级和2010年4月14日青海玉树M_S7.1级地震前均有较明显的前兆异常,此外某些强地震前也有类似的异常信息.进一步对每口井的水温异常信息(诸如异常幅度、持续时间)进行了定量分析,以及每口井对应不同地震的异常曲线形态对比、异常数据的相关性分析,得出这两口井在不同地震前的水温异常形态表现出高度相似性;通过对这些曲线形态的认识与分析,为今后利用水温数据进行经验预报地震的探索开辟一条新路径.另外得出玉树井水温异常的幅度随震级与震中距的不同呈规律性变化,具体表现在震级越大、井震距越小,对应的异常幅度越大、异常持续时间也越长,且玉树井的异常主要是中长周期的异常,这种特性对利用水温异常特征判断未来地震的强度有重要意义;德令哈井则呈现出短临异常特性十分明显的特点,这种特性对利用该井水温数据来判断发震时间有着重要意义.     

滇西实验场及邻区前兆群体异常与成组中强震的关系

本文使用前兆群体异常信息提取的方法,即应用前兆群体非均匀度ID和前兆综合信息量S数学分析,以及相关计算软件,对滇西地震预报实验场及邻区(N24～28°,E98～102°)的断层形变和地下流体各种监测手段的多台项观测资料进行了系统计算分析。研究结果表明:多台多测项前兆群体异常的映震效果优于多台单测项前兆群体异常的应震效果;前兆群体异常与中强地震的对应关系较好,且一组前兆群体异常一般会对应2次以上中强地震,显示了前兆群体异常与地震成组对应关系,而不是以往单次前兆与单个地震一一对应关系。     

Regression analysis of reported earthquake precursors. I. Presentation of data

Around 700 reported precursors of about 350 earthquakes, including the negative observations, have been compiled in 11 categories with 31 subdivisions. The data base is subjected to an initial sorting and screening by imposing three restrictions on the ranges of main shock magnitude (M≥4.0), precursory time (t≤20 years), and the epicentral distance of observation points (X _m≤4.10^0.3M ). Of the 31 subcategories of precursory phenomena, 18 with 9 data points or more are independently studied by regressing their precursory times against magnitude. The preliminary results tend to classify the precursors into three groups:

1. The precursors which show weak or no correlation between time and the magnitude of the eventual main shock. Examples of this group are foreshocks and precursory tilt.
2. The precursors which show clear scaling with magnitude. These include seismic velocity ratio (V _p/V_s), travel time delay, duration of seismic quiescence, and, to some degree, the variation ofb-value, and anomalous seismicity.
3. The precursors which display clustering of precursory times around a mean value, which differs for different precursors from a few hours to a few years. Examples include the conductivity rate, geoelectric current and potential, strain, water well level, geochemical anomalies, change of focal mechanism, and the enhancement of seismicity reported only for larger earthquakes. Some of the precursors in this category, such as leveling changes and the occurrence of microseismicity, show bimodal patterns of precursory times and may partially be coseismic.

In addition, each category with a sufficient number of reported estimates of distance and signal amplitude is subjected to multiple linear regression. The usefulness of these regressions at this stage appears to be limited to specifying which of the parameters shows a more significant correlation. Standard deviations of residuals of precursory time against magnitude are generally reduced when observation distance enters as a second independent variable. The effect is more pronounced for water well level and conductivity rate changes. While a substantial portion of the data seem to suffer from personal bias, hence should be regarded as noise, the observations of a number of strain sensitive phenomena such as strain, water well level, and conductivity rate changes, appear to be internally more consistent. For instance, their precursory times suggest a scaling relationship with the strain energy surface density associated with the main shock. The scaling is not identical for all three phenomena so that they may constitute the imminent, short- and intermediate-term manifestation of the same process, i.e. strain loading, respectively.     

中国新疆温泉、哈萨克斯坦地下流体观测资料前兆异常对比与分析

系统清理分析了中国新疆温泉台、哈萨克斯坦20多年地下流体观测资料.统计结果显示,中国新疆温泉台30井（泉）的氡、流量、水温,哈萨克斯坦卡帕尔井的氦气、扎尔甘特井的流量、博古特井水位、下卡姆井的氦气、萨雷扎斯井水位,映震率较高,在震前都有一定的震兆异常显示,而且前兆异常特征以高值异常为主,异常时间分布特征显示为短期异常.     

STUDY ON CHARACTERISTICS OF GRAVITY VARIATION BEFORE AND AFTER HUTUBI MS6.2 EARTHQUAKE

The Hutubi M_S6.2 earthquake of December 8, 2016 is a pure thrust event in the northern Tianshan thrust fold belt. The earthquake occurred between the Qigu Fault and the Junggar southern margin fault, which are both thrust faults. Based on mobile gravity measurements from 2013 to 2018 in the northern Tianshan, the gravity net adjustment was accomplished using Urumqi absolute gravity observation point as the datum, and the absolute gravity value of surface observation points were obtained. In order to eliminate the seasonal effect on gravity variation, the paper uses the observation data in May per annual as studying objects and obtains the temporal-spatial dynamic evolution images of gravity field differences in the northern Tianshan at different time scales as well as the time series of gravity variation of some points in the adjacent area of the epicenter. The characteristics of regional gravity variation before and after the Hutubi M_S6.2 earthquake on December 8, 2016 and their relations are analyzed systematically. The results show that: 1)The gravity variations in the study area are dramatic in generally, and the contours of gravity variation are consistent with the main faults basically. There was a four-quadrant distribution near the epicenter before the earthquake, and the Hutubi M_S6.2 earthquake occurred near the center of the four-quadrant distribution and at the turn of the gravity variation contour. The three years' cumulative gravity variation before the earthquake and the gravity variation after the earthquake are inversed, and the variation amplitudes are equivalent, suggesting that the M_S6.2 earthquake has released the stress and the energy accumulated before the earthquake. 2)This paper focuses on the analysis of gravity variation at the observation points on both sides of the Junggar southern margin fault near the epicenter. Regional gravity variation and gravity time series show that gravity variations at the same side of the Junggar southern margin fault are basically consistent, however, gravity variations at the different sides of the Junggar southern margin fault are different from each other obviously, indicating the difference of material migration laws in different structural regions. In addition, the strain energy accumulated in the epicenter is basically released after the earthquake, and the area nearby the epicenter tends to be stable. 3)The Hutubi M_S6.2 earthquake occurred near the center of the four-quadrant and at the turn of the high-gradient zone of gravity variation, reflecting the location of strong earthquake is related to the distribution of four-quadrant of regional gravity variation, the high-gradient zone of regional gravity variation and its turn. It has a unique advantage in determining the location of strong earthquake using gravity variation results. The regional spatial-temporal gravity variation before the earthquake is manifested as a systematic evolution process of “steady state→regional gravity anomaly→four-quadrant distribution→earthquake occurring in the reverse process”. Studying the temporal-spatial evolution characteristics of gravity field before and after Hutubi M_S6.2 earthquake has important practical significance for understanding the occurrence law of large earthquakes and capturing the precursory information of earthquakes.     

芜湖皖28井水位异常综合分析

针对2011年芜湖皖28井水位破年变异常,系统梳理该井相关资料,利用水位变幅、相关性分析及相对变差率进行分析.结果表明,该项异常信度较高,反映区域构造活动信息,是周边几次中等强度地震的共同前兆.通过剩余曲线、从属函数等数学方法,对该井历年水位观测数据进行异常识别.研究表明,该井水位异常主要表现为短期异常特征,与该井孔西北、西南侧中等地震有较好的对应关系.     

井水温度动态变化分析—以云南丽江党校井为例

以云南丽江党校井为例,分析了水温基本动态和同震变化特征,并对水温前兆异常变化进行了讨论。基本动态方面,水温水位的对比分析和井温梯度结构显示,党校井的温度探头位于井孔水体与含水层连通的主要部位,含水层中补给水的温度较低,水温动态主要受水位泄流状态和水位变化的影响;同震方面,在水位均为振荡的情况下,水温同震变化形态在不同的泄流状态下存在明显的差异,自流期间为上升—下降—恢复型,非自流期间为下降—上升—恢复型,同震变化反映出的温度探头放置位置和低温水源补给的认识与基本动态分析获得的认识相一致;前兆方面,党校井的水位动态受降雨的趋势性影响,温度探头所在处的地下水体活动剧烈,水温动态前兆变化特征不明显。