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71.
河北应变固体潮汐参数及震例研究   总被引:1,自引:1,他引:0       下载免费PDF全文
选取河北省5个形变台站的观测资料,利用Venedikov调和分析法计算河北省境内M_S4.0以上的潮汐因子、相位等参数,发现应变潮汐因子对地震都有多则半年,少则几周的异常期。宽城台对河北省境内发生M_S4.0以上的地震中,震中距较其他台站最近(震中距最远为350km、最近为100km),资料较好,故在综合分析河北应变台站的基础上,重点选取宽城台的应变潮汐因子对河北2005—2015年地震案例进行简要分析,发现该台对地震的对应率达到60%,虚报率40%,漏报率极低只有14%,前兆异常可信度较高,可作为前兆异常的参考。  相似文献   
72.
2016年6月23日,河北张家口尚义县发生M 4.0地震,发震构造为尚义-平泉断裂。采用基于聚类经验模态分解(EEMD)的HHT计算方法,对尚义M4.0地震强震动记录进行EEMD分解、Hilbert谱变换及谱分析,得到强震动台站的加速度记录分量的时程、FFT谱和边际谱、瞬时能量谱及时频谱,对比分析并认识各种谱的时频特性及规律,做好灾前预防工作,以减少人民生命财产损失。  相似文献   
73.
The petrography and major and trace element concentrations of the sandstones from the Tumengela Formation in the Woruo Mountain area, North Qiangtang Basin, are studied to determine their provenance, intensity of weathering and tectonic setting. The detrital compositions of the Tumengela sandstone samples are dominated by quartz (58.0–70.1 %, average 64.7 %) and lithic fragments (21.8–35.9 %, average 27.3 %), but low in feldspar content (4.9–12.9 %, average 8.0 %). The sandstones can be classified as litharenite and feldspathic litharenite according to their detrital compositions, which is consistent with the geochemical data. The detrital modal compositions reflect that these sandstones are probably derived from a recycled orogenic source. The index of chemical variability (ICV) and SiO2/Al2O3 ratio values suggest that the compositional maturity and recycling were moderate. The weathering indices such as the chemical index of alteration (CIA), plagioclase index of alteration (PIA), chemical index of weathering (CIW), and Al2O3–(CaO* + Na2O)–K2O (A–CN–K) diagram indicate that the intensities of weathering in the source area were moderate. The Al2O3/TiO2, Th/Co, La/Sc, La/Co, Th/Sc, Cr/Th ratio values and the discriminant function of the Tumengela sandstones indicate that the sediments were mainly derived from felsic source rocks, while also mixed with intermediate source rocks. The comparison of rare earth element patterns and its Eu anomalies to the probable source rocks infer that the sandstones were derived from the combination of granite, rhyolite, dacite, and gneisses. The proximal central uplift belt was probably the primary provenance area as evidenced by the petrographical and geochemical features of the Tumengela sandstones. The multidimensional tectonic discrimination diagram based on major elements show a collision setting (80 %) combined with a rift setting (20 %) for the Tumengela sandstones, which is consistent with the general geology of the study areas.  相似文献   
74.
赵建成  杨扬  钟胜强  李锟  陈小刚 《湖泊科学》2016,28(6):1274-1282
实验设计中试水槽装置,模拟研究2种沉水植物轮叶黑藻(Hydrilla nerticillata)和苦草(Vallisneria natans)对农村水体的净化效果,并探讨沉水植物在水体氮、磷去除中的作用.结果显示,沉水植物系统均能显著降低水体中总氮、铵态氮、硝态氮和磷酸盐浓度,去除率分别达到50.5%、84.4%、41.9%和64.6%,且轮叶黑藻组选择20 g/m2,苦草组选择40 g/m2为适种密度.水体流经各串联单元时氮、磷去除负荷存在显著差异,其中总氮、硝态氮、磷酸盐浓度在有植物单元高于无植物单元,铵态氮浓度相反,结合单元内溶解氧浓度、硝化与反硝化细菌总数表明,有植物单元可显著发生反硝化作用,无植物单元可显著发生硝化作用,有无植物串联单元更有利于氮的去除.  相似文献   
75.
通过对哈拉军山地区1∶5万水系沉积物测量数据进行处理,统计分析了各种地球化学参数,总结了元素分布与分配特征。依据R型聚类分析,划分了元素组合,圈定533个单元素异常,19处综合异常。在异常特征分析的基础上,依据成矿地质条件、异常查证结果,划分8个找矿远景区,优选了小哈拉军Au,Cu靶区、大恩别列W,Cu靶区等2个找矿靶区,并对其成矿潜力进行了初步评价,认为这2个靶区具有较好的找矿前景,建议进一步开展矿产勘查工作。  相似文献   
76.
Giant jellyfish (Nemopilema nomurai) outbreaks in relation to satellite sea surface temperature (SST) and chlorophyll-a concentrations (Chl-a) were investigated in the Yellow Sea and East China Sea (YECS) from 1998 to 2010. Temperature, eutrophication, and match–mismatch hypotheses were examined to explain long-term increases and recent reductions of N. nomurai outbreaks. We focused on the timing of SST reaching 15 °C, a critical temperature enabling polyps to induce strobilation and enabling released ephyra to grow. We analyzed the relationship of the timing with interannual variability of SST, Chl-a, and the timing of phytoplankton blooms. Different environmental characteristics among pre-jellyfish years (1998–2001), jellyfish years (2002–2007, 2009), and non-jellyfish years (2008, 2010) were assessed on this basis. The SST during late spring and early summer increased significantly from 1985 to 2007. This indicated that high SST is beneficial to the long-term increases in jellyfish outbreaks. SST was significantly lower in non-jellyfish years than in jellyfish years, suggesting that low SST might reduce the proliferation of N. nomurai. We identified three (winter, spring, and summer) major phytoplankton bloom regions and one summer decline region. Both Chl-a during non-blooming periods and the peak increased significantly from 1998 to 2010 in most of the YECS. This result indicates that eutrophication is beneficial to the long-term increases in jellyfish outbreaks. Timing of phytoplankton blooms varied interannually and spatially, and their match and mismatch to the timing of SST reaching 15 °C did not correspond to long-term increases in N. nomurai outbreaks and the recent absence.  相似文献   
77.
地震的孕育、发生与震源位置及其岩石力学性质有着密切的联系,本文借助数值模拟方法研究了岩石均质度在岩样变形直至破裂过程中对声发射事件活动状态的影响。数值模拟结果表明,岩石非均匀性对岩样声发射活动状态的时间演化过程有着较大影响,所得结论进一步支持了分区研究强地震前兆异常的必要性。  相似文献   
78.
八宝山断裂带逸出氡的地球化学特征及其映震效能   总被引:16,自引:3,他引:13  
杜建国  宇文欣 《地震》1998,18(2):155-162
给出了1992年5月至1996年12月八宝山断裂层气中氡的浓度实例测值,并讨论了氡异常的影响因素及其与地震的关系。二个测点断层气中氡的浓度变化范围较大,且a测点的氡浓度值离散度较大,其平均值为6.5Bq/L,均方差为2.3,b测点均值为4.4Bq/L,均方差为1.6。氡的原始测值具有年变旋回,测点气温、气压和3.2m地温也具有明显的年变规律,温度和土壤湿度是控制氡浓度年变的主要因素。氡的浓度在无震  相似文献   
79.
Quantitative studies on the evolution and dynamics of the deepwater area of Pearl River Mouth basin (PRMB) were carried out based on the latest geological and seismic data.The study area is generally in an extensional state during the Cenozoic.The major extension happened in the earlier syn-rift stages before 23 Ma and the extension after 23 Ma is negligible.Two rapid subsidence periods,32-23 Ma and 5.3-2.6 Ma,are identified,which are related to the abrupt heat decay during margin breakup and the collision between the Philippine Sea plate and the Eurasian plate,respectively.The strongest crustal thinning in the Baiyun (白云) sag may trigger the syn-rift volcanism along the weak faulted belt around the sag.The Cenozoic tectonic evolution of the study area could be divided into five stages:rifting (~0-40 Ma),rift-driR transition (~40-32 Ma),early post-breakup (~32-23 Ma),thermal subsidence (~23-5.3 Ma) and neotectonic movement (~5.3-0 Ma).  相似文献   
80.
测震学综合应用软件系统在地震监测工作中的应用   总被引:1,自引:0,他引:1  
简要说明了测震学综合应用软件系统的系统特点;详细介绍了该软件系统的功能;重点分析了该软件系统在地震监测工作中的应用,如在地震编目、序列自动编目、测震台网控制震级能力评定、辅助台网布设方案设计及地震现场应急等方面的应用。用户反馈的信息表明,测震学综合应用软件系统可以在地震监测中发挥重要作用。  相似文献   
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