鄂尔多斯块体南缘及邻区地震地下流体异常特征研究
发布时间：2018-10-11 08:13
【摘要】：地震地下流体(以下简称地下流体)观测,是基于震前地下流体受构造影响产生变化这一机理进行的观测手段。实践表明,地下流体观测不可避免的受到多种因素的影响,由于不同观测点观测条件的差异,其受不同影响因素的影响程度也不尽相同。如气象因素中的气压、降水,人文活动中的抽水、注水,以及荷载等干扰因素,都可能使地下流体的物理性质、化学性质发生变化,而这些干扰信息可能与震前的前兆异常信息交织在一起。因此研究地下流体观测中的干扰因素,对于识别与提取地震前兆信息及对认识含水层特性至关重要,有效分析和提取地下流体观测中的影响因素,对深入认识前兆观测资料和发现前兆异常具有重要意义。本文系统研究了鄂尔多斯块体南缘地下流体观测中典型干扰异常(降雨、河水洪峰、气压等荷载因素)的影响特征,指出降雨对凤翔井水位影响明显,并在一定范围内与水位变化呈指数相关关系,深入研究发现,降雨通过荷载效应、渗入断层及改变水位埋深三种途径影响区域构造应力场,并可能触发区内中、强地震活动;对双王井水位与渭河洪峰关系的分析结果显示,洪峰荷载对双王井水位的加载系数处于0.84~1.03之间,这一分析结果可有效的消除洪峰荷载对水位的影响;对于周至深层承压井,可通过对水位的气压效率和相关系数来消除气压对水位的影响,当气压效率或相关系超出正常范围时,研究区内可能会发生中、强地震。此外,本文还清理了1980~2010年30年期间鄂尔多斯南缘及邻近地区地震事件42个,涉及地下流体测点64个,共计流体测项震例168个,并从测项、震前异常时间、异常形态三个方面对流体前兆异常进行了统计,统计结果显示以测项分类统计水(气)氡所占比例较大(占47%);按震前异常时间统计以的短期异常为主(占47%);按异常形态统计以高值异常为主(占60%)。对统计样本的前兆异常持续时间与震中距统计结果显示,异常持续时间越长,震中距越小,可以理解为异常最先出现在震源区附近,随着时间持续,异常有向外扩散的趋势。
[Abstract]:The observation of seismic underground fluid (hereinafter referred to as underground fluid) is based on the mechanism of tectonic change of underground fluid before earthquake. The practice shows that the observation of underground fluid is inevitably influenced by many factors, and the degree of influence of different factors is different due to the difference of observation conditions at different observation points. For example, atmospheric pressure, precipitation, pumping, water injection, and loads in human activities may all cause changes in the physical and chemical properties of underground fluids. The interference information may be intertwined with the precursory anomaly information before the earthquake. Therefore, it is very important to study the interference factors in the observation of underground fluid to identify and extract the seismic precursor information and to recognize the characteristics of the aquifer, and to analyze and extract the influencing factors in the observation of underground fluid effectively. It is of great significance to understand the precursory observation data and find precursory anomalies. In this paper, the influence characteristics of typical disturbance anomalies (rainfall, river water Hong Feng, pressure and other load factors) in the underground fluid observation of the southern edge of Ordos block are systematically studied, and it is pointed out that rainfall has obvious influence on the water level of Fengxiang well. It is found that rainfall affects regional tectonic stress field through load effect, infiltration of fault and change of depth of water level through load effect, and may trigger strong earthquake activity in the region. The analysis of the relationship between Shuangwang well water level and Hong Feng of Weihe River shows that the loading coefficient of Hong Feng load on water level of Shuangwang well is between 0.84 and 1.03, which can effectively eliminate the influence of Hong Feng load on water level. The influence of air pressure on water level can be eliminated by the pressure efficiency and correlation coefficient of water level. When the pressure efficiency or the relation between pressure and pressure is beyond the normal range, moderate and strong earthquakes may occur in the study area. In addition, 42 earthquake events in the southern margin of Ordos and adjacent areas during the period of 1980 to 2010 have been cleared, involving 64 underground fluid sites, a total of 168 fluid term seismograms, and the anomalous time before the earthquake. Three aspects of abnormal morphology are used to calculate the precursory anomalies of fluid. The statistical results show that the proportion of radon in water (gas) is larger (47%), the short-term anomaly (47%) and the high value anomaly (60%) are dominant in the statistics of water (gas) according to the abnormal time before the earthquake. The results show that the longer the duration of the anomaly, the smaller the epicentral distance is, which can be understood as the first occurrence of the anomaly near the focal area, and the tendency of the anomaly to spread outward with the duration of the anomaly.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.7
本文编号：2263474
[Abstract]:The observation of seismic underground fluid (hereinafter referred to as underground fluid) is based on the mechanism of tectonic change of underground fluid before earthquake. The practice shows that the observation of underground fluid is inevitably influenced by many factors, and the degree of influence of different factors is different due to the difference of observation conditions at different observation points. For example, atmospheric pressure, precipitation, pumping, water injection, and loads in human activities may all cause changes in the physical and chemical properties of underground fluids. The interference information may be intertwined with the precursory anomaly information before the earthquake. Therefore, it is very important to study the interference factors in the observation of underground fluid to identify and extract the seismic precursor information and to recognize the characteristics of the aquifer, and to analyze and extract the influencing factors in the observation of underground fluid effectively. It is of great significance to understand the precursory observation data and find precursory anomalies. In this paper, the influence characteristics of typical disturbance anomalies (rainfall, river water Hong Feng, pressure and other load factors) in the underground fluid observation of the southern edge of Ordos block are systematically studied, and it is pointed out that rainfall has obvious influence on the water level of Fengxiang well. It is found that rainfall affects regional tectonic stress field through load effect, infiltration of fault and change of depth of water level through load effect, and may trigger strong earthquake activity in the region. The analysis of the relationship between Shuangwang well water level and Hong Feng of Weihe River shows that the loading coefficient of Hong Feng load on water level of Shuangwang well is between 0.84 and 1.03, which can effectively eliminate the influence of Hong Feng load on water level. The influence of air pressure on water level can be eliminated by the pressure efficiency and correlation coefficient of water level. When the pressure efficiency or the relation between pressure and pressure is beyond the normal range, moderate and strong earthquakes may occur in the study area. In addition, 42 earthquake events in the southern margin of Ordos and adjacent areas during the period of 1980 to 2010 have been cleared, involving 64 underground fluid sites, a total of 168 fluid term seismograms, and the anomalous time before the earthquake. Three aspects of abnormal morphology are used to calculate the precursory anomalies of fluid. The statistical results show that the proportion of radon in water (gas) is larger (47%), the short-term anomaly (47%) and the high value anomaly (60%) are dominant in the statistics of water (gas) according to the abnormal time before the earthquake. The results show that the longer the duration of the anomaly, the smaller the epicentral distance is, which can be understood as the first occurrence of the anomaly near the focal area, and the tendency of the anomaly to spread outward with the duration of the anomaly.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.7
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