北京西北延庆—怀来盆地的地震观测及减轻地震灾害研究

根据历史地震记载、近期地震活动性和构造应力场资料,分析了北京西北延庆－怀来盆地的潜在地震危险性。指出自１９９５年７月２０日至１９９６年７月３０日发生于延庆－怀来盆地的ＭＬ＝４．１地震序列的震源分布,揭示了分布于延庆－怀来盆地的两条共轭断层,位于这两条共轭断层延长线交汇处的怀来县城地区具有断层闭锁区的特征,该闭锁区域的线性尺度与一个６．０级地震震源区的线性尺度相当,但延庆－怀来盆地近期微震活动未显示     

海城地震余震活动的再研究

截止１９９５年４月，海城－营口地震区已发生ＭＬ≥３．６级余震４２５次。西方对余震ｂ值随时间的变化、余震时空发展的特点、大余震发生前后的余震特征等做了进一步研究，所得主要结果如下：（１）随着时间的推移，余震ｂ值逐渐增大，并趋于稳定。（２）今后仍有可能发生２－３次ＭＬ５．０级左右的余震。     

江汉—洞庭盆地地震活动性研究

在收集了江汉—洞庭盆地及其邻近地区的历史地震及仪器观测地震资料的基础上,本文对江汉—洞庭盆地的地震时空分布、震源应力场特征以及未来地震活动的发展趋势作了探讨。     

论延庆盆地北缘断裂带的分段与地震预测

依据古地震学的断层习性资料，提出延庆盆地北缘断裂带５个段落的分段模型。各个段落的构造地貌学特征具有明显差异。４个主要不连续性形成段落边界：断层分叉和断层弯曲是非持久性段落边界，而凸出体和雁行断错是持久性段落边界。预期强震（Ｍ≥７）的发生时间在未来１０００～２０００ａ内，最有可能的地点为断层段落Ⅱ。     

张北-尚义地震与大同-阳高地震地震活动对比研究

张北－尚义地震与大同－阳高地震虽然相距不远,但在地震活动性上有较大的差异。大同－阳高地震前,区域地震活动、断裂带附近微震活动、震源邻区地震活动趋势、地震活动空区展布和余震分布都与北东或北西向这组共轭构造一致;张北－尚义地震前,区域地震活动、断裂带附近微震活动、震源邻区地震活动趋势、地震活动空区展布和余震分布则与近南北或近东西向这组共轭构造平行。产生这种方向差异的原因可能是构造条件的差异以及附加应力场的不同     

怀来盆地的地震活动与活动断裂

怀来盆地的地震活动与活动断裂王培德田玉红李春来陈运泰（中国北京１０００８１国家地震局地球物理研究所）主题词怀来盆地地震活动活动断裂数字地震台网怀来盆地位于北京西北部，最近处距北京市区仅约６０多千米．该地区地震活动活跃．据历史记载，１３３７年怀来地区曾...     

南黄海6.1级地震前的地震活动性研究

通过应用最大熵谱法,有序聚类法和地震活动过程,地震相关性的分析,论证了华东地区正处于１９７１年以来的地震活动幕后期,具有发生６级以上地震的可能。１９９６年１１月９日南黄海６．１级地震的发生与这一分析基本相符,作还就地震形势分析的有关科学问题进行了讨论。     

龙泉山断裂带地震活动性浅析

通过对龙泉山断裂带东坡断裂和西坡断裂的地震活动性研究,表明该带是一条活断层。历史地震记载和现今地震活动均呈现沿断裂带分布,地震活动呈现周期性和南北跳迁的特点,近10年来地震监测资料表明该带地震活动在增强。     

东北地震活动性短期预报方法研究

研究了1970年以来东北地区发生的MS≥5·0浅源地震孕育过程中地震活动性参数和地震活动图像的变化特征,并对地震活动性参数进行了比较系统地综合预报效能评价,结果显示:东北9次(组)浅震地震前,所研究的5项地震活动性参数中,88·9%出现了持续3个月以上的短期异常变化,且5项参数R值评分结果都满足97·5%的置信水平;88·9%地震前震源区附近出现了孕震空区,有87·5%孕震空区在空区边缘或空区内部出现了ML≥4·0逼近地震,逼近地震以单个或成对的形式出现。66·7%的地震在震源区附近出现了地震条带异常。最后给出东北地区中强震的短期预报方法,这对未来东北地区的地震预报工作将起着一定的参考意义。     

四川及邻区强震前地震活动性参数的变化特征

对四川及邻区最近30多年来发生的18组6级以上强震前多种地震活动性参数的变化特征进行了分析研究。震例总结显示,衡量区域地震活动异常增强或平静的中等地震月频次异常可作为判断中期是否发生强震的指标;在区域中等地震活动出现异常的前提下,区域小震平静异常可作为判断短期是否发生强震的依据。而根据A值和GL值的空间异常分布范围,结合地震构造背景及其它方法,可缩小预报区域。     

河套盆地Ms≥5.5级地震前地震活动性特征

选取河套盆地及周边地区 (北纬 3 8.5°～ 42°,东经 1 0 6°～ 1 1 3°)为研究区 ,采用《中国地震目录》1 970～ 2 0 0 0 .8,ML≥ 2 .0级地震资料 ,应用“八五”、“九五”攻关研究成果 ,通过对河套盆地中强地震前地震活动图像和测震学指标的全时空扫描分析 ,提取具有预报效能的地震活动图像及参数 ,然后对河套盆地地震地质构造特征、历史中强地震时空分布特征和运用具有预报效能的地震图像、参数对河套盆地近期地震活动进行分析 ,认为河套盆地发生中强地震的危险性不容忽视     

海城地震窗地震活动异常提取及其预报效能

一个时间序列可以分解为趋势周期(含季节周期)部分和不规则随机部分.趋势周期部分是序列的潜在部分,它反映了增长、下降和周期影响的长期变动规律,具有确定性或可预测性;不规则随机部分包含残差、突然等因素引起的突变量,具有不可预测性.当趋势周期部分被确定后,它可通过计算得到.本文研究了1975年海城Ms7.3地震孕育、发生的断...     

汉中与安康盆地地震活动特征

根据块体内地震受块体边缘地震影响的观点,对汉中与安康盆地的历史及现代地震活动特点、规律进行了讨论和分析。得到这样结果：(1)块体内断陷盆地的地震活动水平将小于块体边界上的地震活动水平;(2)块体内盆地的地震活动,主要受块体边缘较大地震活动的影响,反映块体边界较大地震发生前后其附近构造的调整运动;(3)当与块体内盆地较近的块体交界带上发生大地震时,应注意盆地的地震危险。     

Re-appraisal of seismicity and seismotectonics in the north-eastern Algeria Part I: Review of historical seismicity

As large destructive seismic events are not frequent in Algeria, anexhaustive knowledge of the historical seismicity is required to have arealistic view of seismic hazard in this part of the world. This research workpresents a critical reappraisal of seismicity in the north-eastern Algeria forseismotectonic and seismic hazard purposes. This part of work focuses onthe seismicity of pre-1900 period for the area under consideration[33^°N-38^°N, 4^°E-9.5^°E]. By going back tothe available documentary sources and evaluating and analysing the eventsin geographical, cultural and historical context, it has been possible toidentify 111 events, from 1850–1899, which are not reported in therecent Algerian catalogue. Several spurious events, reported in standardlistings, have been deleted and nine unknown events have been discovered.It is quite clear that macroseismic information derived from press reportsand published documents in Algeria, under certain conditions, is veryincomplete, even for destructive earthquakes, located in the countrysideaway from communication centres. One of the reasons for this iscensorship, noticeable during the colonisation period. Critical analysis ofnewly collected information has allowed the determination and/or theimprovement of the macroseismic parameters of each event, such aslocation, maximum epicentral intensity and magnitude to produce anearthquake catalogue as homogeneous and complete as the available data,for the zone under study. The criteria used in this research are explainedand eight historical earthquakes have been the subject of retrospectivemacroseismic field construction.The investigation of historical earthquakes is one of the most important taskin studying seismotectonic for seismic hazard evaluation purposes.     

昆仑山口西地震和汶川地震前中源地震活动特征研究

研究2001年昆仑山口西地震和2008年汶川地震前的中源地震活动特征,与唐山地震前的特征进行比较,发现:3次大地震前曾发生6或7次h≥60 km的中源地震,且"大震前中源地震活跃的时间跨度T"约5年或5年多。这是大震前中源地震活动最主要的两个特征,包含了孕育大地震的一些重要信息。其他特征还有:中源地震的活动—平静交替、临近大地震前的地震平静、呈条带分布和(或)地震空区等特征,这与大震前壳内地震活动性的一些特征类似。     

Bending-related faulting of the incoming oceanic plate and its effect on lithospheric hydration and seismicity: A passive and active seismological study offshore Maule,Chile

We have studied the dependency between incoming plate structure, bending-related faulting, lithospheric hydration, and outer rise seismic activity offshore Maule, Chile. We derived a 2D Poisson's ratio distribution from P- and S-wave seismic wide angle data collected in the trench-outer rise. High values of Poisson's ratio in the uppermost mantle suggest that the oceanic lithosphere is highly hydrated due to the water infiltration through bending-related normal faults outcropping at the seafloor. This process is presumably facilitated by the presence of a seamount in the area. We conclude that water infiltrates deep into the lithosphere, when it approaches the Chile trench, producing a reduction of crustal and upper mantle velocities, supporting serpentinization of the upper mantle. Further, we observed a mantle Vp anisotropy of 8%, with the fast velocity axis running normal to the abyssal hill fabric and hence in spreading direction, indicating that outer rise processes have yet not affected anisotropy.The first weeks following the megatrust Mw = 8.8 Maule earthquake in 2010 were characterized by a sudden increase of the outer rise seismic activity, located between 34° S and 35°30′ S. We concluded that this phenomenon is a result of an intensification of the water infiltration process in the outer rise, presumably triggered by the main shock, whose epicenter was located some 100 km to the south east of the cluster.     

Re-appraisal of seismicity and seismotectonics in the north-eastern Algeria Part II: 20th century seismicity and seismotectonics analysis

The main objective of the research work isthe homogenisation of the two recentAlgerian earthquake catalogues for thecommon covered period of time, from 1900 to1990, for the region under considerationlimited by [33^°N–38^°N,4^°E-9.5^°E] and the updatingof the catalogue for the twentieth century(1900–2000). To mitigate the deficiencyof the incompleteness of catalogue, aneffort was made to establish a correlationbetween surface-wave magnitude Ms andbody-wave magnitude m_b in the form ofMs = a + b (m_b). A complete, exact andhomogeneous earthquake catalogue as much aspossible, comprising 870 seismic events,has been compiled. Seismicity analysis ofthe region shows a strong concentration ofseismicity along a band of no more than400 km width oriented mainly in theeast-west direction parallel to the coast.Moreover, earthquakes in this zone arerather associated to strike-slip mechanism.The focal mechanism show a regional stressregime that corresponds to horizontalcompression in NW-SE to N-S direction. As aresult of the review of the seismicity ofnorth-eastern Algeria from the compilationof checked and corrected data and itscorrelation with other geologic andgeophysical investigations based ondocumentary sources, it was possible toconstruct a most complete seismotectonicmap. It leads also to delineate fourseismogenic zones in the Tellian Atlas, aless important zone in the Saharan Atlas, asixth zone at the boundary of both Atlasand finally, a seventh one along thecoastal zone. The seismicity-active faultscorrelation of some of these defined zonesis examined in details with a specialattention to the Saharan Atlas zone, theHodna and Biban zone as well as Soummam andBabor zone where further research workallowed to find some neotectonic featuresconsidered as a significant sign of recenttectonic activity.