菏泽—濮阳及附近地区震源深度及波速比变化

计算了发生在濮阳及附近地区(35.5°~36.0°N,115.1°~115.7°E)地震的波速比,并进行T检验。结果表明,研究区内2001~2008年发生的41次ML≥2.6级地震波速比值属于正常变化。通过1970~2008年菏泽—濮阳及附近地区(35.1°~36.0°N,115.1°~115.7°E)发生的ML≥3级地震震源深度分析,发现1983年(11月7日菏泽5.9级地震前,研究区内震源深度变化大(-h=19 km),而5.9级地震后至2008年震源深度浅(-h=13 km)的特点。     

蒙宁交界区b值时空变化特征

选取1970—2019年蒙宁交界区中国台网中心地震目录,结合研究区地质构造,分析震级与地震频次以及时间与地震频次的关系。利用极大似然法,设定不同的窗长和步长,对研究区进行b值时空扫描,对比b值时间曲线,发现某些中强震发生在b值下降到异常水平然后上升的过程。采用矩形窗和圆形窗分别进行空间扫描,对比发现,研究区低b值分布在(104°—105°E,36°—38°N)区域;对研究区16次中强震进行震例回溯,结果发现,5次地震发生在低b值区域,表明低b值区有发生中强震的可能。     

南北地震带潮汐触发地震的统计学证据

自19世纪90年代以来,潮汐是否会触发地震这个问题一直备受关注.本研究选用1970年1月1日至2017年5月31日期间南北地震带(20°N—40°N,97°E—105°E)M_L≥2.0地震目录资料,通过测量南北地震带地区地震事件与潮汐的相关性来研究潮汐是否能触发地震.选用完备性检测、G-C法、R/S分析方法对原始地震目录进行预处理,分别构成未去除余震和去除余震每日地震数量时间序列,利用经验模态分解和快速傅里叶方法,对比分析了潮汐与每日地震数量构成的时间序列频谱特征.结果表明,在本文研究区域,两种每日地震数量时间序列均与潮汐的月潮周期、半月潮周期存在相关性,并且去除余震后的每日地震时间序列的优势频率更加集中,表现的相关性更好.此外,Schuster’s测试结果也进一步证明,研究区域地震活动性与固体潮汐存在显著统计相关性.     

四川强震前的前兆异常资料循证研究

正1970—2013年,四川及邻近地区(97°E~109°E,26°N~35°N)共发生6级以上地震40次,7级以上地震7次。本文主要对四川6级以上地震前的地壳形变、地下流体、电磁学科异常从基于前兆观测异常与地震、基于《中国震例》、基于四川省《地震趋势研究报告》中前兆观测异常3个方面进行了循证研究。     

利用图像信息方法研究芦山MS7.0地震前川滇及附近地区的图像异常

图像信息方法是一种基于统计物理学的地震预测方法. 该方法通过严格的统计检验给出地震活动状态显著偏离平均状态的地区(即显著平静或显著活跃的地区), 称为“地震热点”. 以往研究结果表明该方法是一个预测效能较高的中长期地震预测方法. 本文利用中国地震台网中心提供的1970年以来的地震目录, 在剔除余震、 选取完备震级的基础上, 基于前期研究工作结果中预测效能较高的计算参数, 即网格尺度为2°×2°、 预测时间窗为9年, 分析2008年汶川M_S8.0地震后到2013年芦山M_S7.0地震前川滇地区的图像信息演化过程. 结果表明, 2009—2010年间芦山M_S7.0地震震中附近的鲜水河断裂带、 龙门山断裂带和安宁河断裂带交汇区(29°—31°N, 101°—105°E)存在明显的地震热点, 2011—2012年该地震热点缩小至(29°—31°N, 101°—103°E)范围, 2012年以后消失, 继而于2013年发生芦山M_S7.0地震. 本文还对比研究了网格尺度为1°×1°时的图像信息演化过程, 结果显示2009—2010年芦山地震附近的新津—成都—德阳断裂南部、 龙泉山西缘断裂南段、 马边—盐津断裂带、 峨边断裂带、 天全—萦经断裂带(29°—30°N, 103°—104°E)也出现过地震热点, 2011年以后该热点消失, 2013年发生芦山M_S7.0地震. 本文讨论了计算参数对预测结果的影响, 并根据目前存在的地震热点分析了川滇及附近地区今后强震发生的可能地点.      

青海祁连县默勒5.0级地震

1984年2月17日10点37分青海省祁连县东南(37°42′N,100°10′E)发生了5级地震(青海台网测定)。该区曾于2月13—16日发生3次M_L=2.0—3.6级地震,截止2月21日共发生7次M_L=2.8—3.3级余震。青海省地震局及国家地震局兰州地震研究所联合对这次地震进行了考察。     

江苏南部地区中强地震前地震活动性图像的演化特征

选取苏南地区（30°-35°N,115°～125°E）为研究区,采用中国地震局提供的1970年以来ML≥2．0级地震活动的资料,经过完整性和一致性处理,对研究区进行全时空扫描确定中短期预备空区,以分析该地区中强地震前地震活动性图像的时间、空间及强度演化特征。     

广西北流-广东化州交界5.2级地震前RTL异常特征

采用"区域—时间—长度算法"(简称RTL算法)对2019年10月12日发生在广西北流-广东化州交界的5.2级地震进行了回顾性检验.选取2015年10月11日至2019年10月10日中国地震台网测定的ML2.0以上地震目录,根据震中附近所在区域确定选取范围:109.0°～112.0°E,20.5°～23.5°N,并以0....     

云南小江断裂带北段动态触发现象研究

论文通过分析云南小江断裂北段(26°N—27.5°N,102.3°E—103.7°E)密集地震台阵(38个地震台组成)2012-2015年的地震记录,分别用基于频谱图的人工识别及小震目录的β统计两种触发判定标准研究远震是否对研究区域内小震活动存在动态触发.发现在研究时段内发生的36个7级以上远震中,7个存在着明显的触发现象.论文应用匹配定位法,实现了被触发小震的定位并计算了研究区域内触发潜能的分布,以及基于地震活动性变化的触发强度分布,讨论了小江断裂带北段断层应力所处状态及其对于强震危险性分析的启示.     

中国华北地区每年地震强度的预测

本文以华北地区(32°—44°N,110°—126°E)地震活动性资料为基础,运用模糊数学中的信息检索方法预测华北地区每年可能的地震强度。 对于每一个待报的年度,该方法选用这年度前三年的资料,选取8个地震活动性基本指标:每年地震折合到Ms=4.0—4.4的折合地震总数N,地震能量E,地震分布所占平方度数n,各平方度之间的平均距离(?)以及这些指标相邻两年差的绝对值|△N|,|△E|,|△n|和|△(?)|。每年地震强度的分类为:(1)Ms≤4.9;(2)5.0≤Ms≤5.9;(3)Ms≥6.0。对1961年至1988年的资料检验和预报结果表明,效果均良好。     

Changes in sediment transport in the Kuye River in the Loess Plateau in China

In this paper, the changes in sediment transport over 51 years from 1955 to 2006 in the Kuye River in the Loess Plateau in China are assessed. Key factors affecting sediment yield and sediment transport, such as precipitation depth, discharge, and human activities are studied. To investigate the changes in sediment yield in this watershed, a trend analysis on sediment concentration, precipitation depth, and discharge is conducted. Precipitation depths at 2 Climate Stations （CSs）, as well as discharge and sediment transport at 3 Gauging Stations （GSs） are used to assess the features of sediment transport in the Kuye River. The rtmoff modulus （defined as the annual average discharge per unit area, L/（s·km^2）） and the sediment transport modulus （defined as the annual suspended sediment transport per unit area, t/（yr km^2）） are introduced in this study to assess the changes in runoff and sediment yield for this watershed. The results show that the highest average monthly discharge during the study period in the Kuye River is 66.23 m^3/s in August with an average monthly sediment concentration of 88.9 kg/m^3. However, the highest average monthly sediment concentration during the study period in the Kuye River is 125.34 kg/m^3 and occurs in July, which has an average discharge of 42.6 m^3/s that is much less than the average monthly discharge in August. It is found that both the runoff modulus and sediment transport modulus at Wenjiachuan GS on the Kuye River has a clear downward trend. During the summer season from July to August, the sediment transport modulus at Wenjiachuan GS is much higher than those at Toudaoguai and Longmen GSs on the Yellow River. The easily erodible loess in the Kuye River watershed and the sparse vegetation are responsible for the extremely high sediment yield from the Kuye River watershed. The analyses of the grain size distribution of suspended load in the Kuye River are presented. The average monthly median grain size of suspended load in the Kuye River is largest in February and then decreases until June. In July, the average monthly median grain size of suspended load approaches another peak and decreases until September. Then, the median grain size of suspended load starts to increase until February of the following year. However, the average monthly median grain size of suspended load in the Yellow River at Toudaoguai and Longmen GSs is the smallest between early summer and late fall The median grain size in the Yellow River starts to increase in November and approaches the largest size in January.     

Variations in trace gas concentrations in different environments in India

Observations of trace gases (SO₂, NH₃, NO₂ and O₃) were made during the period 1981 to 1984 at 6 different locations representative of urban industrial, urban, nonurban, thermal power plant and marine environment. Diurnal variations of the trace gases were studied in an urban environment. Except in the urban industrial environment, the concentration of NH₃ was found in the range of background values. Also, the average concentrations of NO₂ and O₃ at the different environments were in the order of background values. However, the concentrations of SO₂ were substantially higher by about 7 times, in urban industrial and thermal power plant environments. The diurnal variations of SO₂, NH₃ and NO₂ showed anitphase relationship with surface temperature at the urban environment station which is relatively free of industrial pollution. Discussion is centred on trace gas variations in different environments in India together with the values reported for various countries in the world.     

TritiogenicHe in groundwater in Takaoka

³He/⁴He ratios up to 3.5 times the ratio of atmospheric He were found in groundwater samples. The³He enrichment can be attributed to radiogenic³He produced by in-situ beta-decay of³H. This shows that tritiogenic³He is accumulating in confined waters. From tritiogenic³He and³H concentrations, ages of groundwaters can be calculated. Detection of tritiogenic³He gives a tool to trace a tritium contamination which occurred in the past and cannot be assessed only by the³H counting method.     

Applied volcanology in geothermal exploration in Iceland

In an active spreading area like Iceland, where the regional geothermal gradient is in the range 50–150°C/km, it is normally not a problem to find high enough temperature with deep drilling, but the difficulties arise with finding permeable layers at depth within the strata. Various volcanological methods can be applied in the search for aquifers and geothermal reservoir rocks. The flow pattern (as deduced from deuterium studies) indicates that the thermal water flows preferentially along high porosity stratiform horizons and dyke swarms from the recharge areas in the highlands to the hot spring areas in the lowlands. The primary porosity of the volcanic strata is dependent on the chemical composition and the mode of eruption of the volcanic units. Both the reservoir rocks and the flow channels forming the geothermal plumbing system are thought to vary from the Tertiary to the Quaternary provinces due to environmental conditions at the eruptive sites.     

2008年云南地震灾害概况

列出了2008年云南省破坏性地震目录.在此基础上,结合云南省地震局的地震灾害评估资料,总结了2008年云南地震灾害的主要数据和特性.最后列出1990～2008年云南地震灾害的相应数据,并进行了简要对比.     

2007年中国大陆地震灾害损失述评

在列出2007年中国5级以上地震目录的基础上,结合有关省(自治区、直辖市)地震局的地震灾害评估资料,总结出2007年中国大陆地震灾害的主要数据和特性。最后列出1990—2007年中国大陆地震灾害的相应数据,并进行了简要的比较。     

Projected changes in flood indices in selected catchments in Poland in the 21st century

The aim of this study is to estimate likely changes in flood indices under a future climate and to assess the uncertainty in these estimates for selected catchments in Poland. Precipitation and temperature time series from climate simulations from the EURO-CORDEX initiative for the periods 1971–2000, 2021–2050 and 2071–2100 following the RCP4.5 and RCP8.5 emission scenarios have been used to produce hydrological simulations based on the HBV hydrological model. As the climate model outputs for Poland are highly biased, post processing in the form of bias correction was first performed so that the climate time series could be applied in hydrological simulations at a catchment-scale. The results indicate that bias correction significantly improves flow simulations and estimated flood indices based on comparisons with simulations from observed climate data for the control period. The estimated changes in the mean annual flood and in flood quantiles under a future climate indicate a large spread in the estimates both within and between the catchments. An ANOVA analysis was used to assess the relative contributions of the 2 emission scenarios, the 7 climate models and the 4 bias correction methods to the total spread in the projected changes in extreme river flow indices for each catchment. The analysis indicates that the differences between climate models generally make the largest contribution to the spread in the ensemble of the three factors considered. The results for bias corrected data show small differences between the four bias correction methods considered, and, in contrast with the results for uncorrected simulations, project increases in flood indices for most catchments under a future climate.     

冬季亚洲中强震与夏季我国东部主雨带的准同纬性

根据1954～2003年50年亚洲中强震与我国地温资料，分析了冬季震中纬度—震涡中心纬度—冬季我国东部强地热涡中心纬度—夏季我国东部主雨带纬度4者之间的相互关系，发现冬季中强震与夏季主雨带之间具有较好的准同纬性. 这是每年汛期降水预报的一个指标. 文中也讨论了应用此预报指标时的一些特例.     

Advances in ground motion studies in China

This paper briefly summarizes the works in the processing of strong ground motion data, the factors affecting strong ground motion, the modeling of strong ground motion and the calculating of broad-band response spectrum which have been done recent years by engineering seismologists and seismologists of China. In addition, we think back to the international cooperation in strong ground motion of the recent years and make some expectations for the future.