共查询到19条相似文献，搜索用时 84 毫秒
1.
叙述并分析了山西地震带地质构造特点和近期的中强地震及震群活动基本特征，在此基础上，与大同一阳高地震进行了分析对比，认为大同－阳高地震是山西地震带近期地震活动的继续，而山西地震带今后强震活动阶段的开始，其标志应是ＮＮＥ向新生代断陷内的中强地震活动，因此在分析和预估山西地震带今后地震发展时，应密切注视这一地带的地震活动。 相似文献
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叙述井分析了山西地震带地质构造特点和近期的中强地震及震群活动基本特征，在此基础上，与大同一阳高地震进行了分析对比，认为大同－阳高地震是山西地震带近期地震活动的继续，而山西地震带今后强震活动阶段的开始，其标志应是ＮＶＥ向新生代断陷内的中强地震活动，因此在分析和预估山西地震带今后地震发展趋势时，应密切注视这一地带的地震活动。 相似文献
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研究了大化水库附近近期的地震活动特征及其与构造的关系。近期的地震活动与前期水库附近发生的地震有显著不同，几次较大地震震源机制解表明；震源应力场随时间变化明显，且与现代区域应力场不甚一致，震源错动方式也较特殊。 相似文献
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用现今小震推断洪洞、临汾两次历史大震的震源断层 总被引：5，自引：1，他引：5
山西临汾地区是一个历史强震多发区，1303年和1695年发生了洪洞（M＝8）和临汾（M＝73／4）两次特大地震，这两次地震所在区域至今仍在持续不断的小地震活动，具有明显的大震区地震长期活动特征，我们对临汾无线传输地震台网记录的1987－1999年期间发生的1670次中，小地震重新进行了震源定位，根据对这些地震震源位置三维空间分布特征和震源机解制的分析，认为洪洞地震的震源断层应是长80km，埋深5－26km的NNE走向，高倾角的右旋走滑型断层，而临汾地震的震源断层是长70km，埋深5－22km的NWW走向，高倾角的左旋走滑型断层。这与洪洞，临汾两次大震极震区的等震线及该地区应力场的构造环境是吻合的。 相似文献
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台湾海峡7.3级地震及其震后地震趋势研究 总被引：4，自引：0，他引：4
通过对台海海峡７．３级地震序列研究表明，该地震是一次板内的主－余震型地震，震源机制解确定此次地震是ＮＷ走向断裂的走滑正断层错动；震区地震构造背景和震前的地震活动异常图像与我国东南沿海成一体性，表明属于我国东南涡海地震带的地震活动震前出现多项地震学异常。震兆演化过程存在明显的阶段性，本次地震有一寂的可预测性，根据地震活动分幕结果，认为近期东南沿海的一系列中强震活动属于该带第五活跃幕的地震群体活动并预 相似文献
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黑龙江省十年地震危险性评估 总被引：1，自引：0，他引：1
本文研究了东北深震区深震活动的时序特征，发现深源地震活动具有较清晰的平静一活动轮回，并且在深震活动之后，黑龙江省的浅源地震活动相对增强。根据历史地震活动特征与近期小分布特点。作者给出了未来十年时间内，浅源中强震发生的二条危险区段。 相似文献
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青藏高原的地震构造与地震活动 总被引：3，自引：0，他引：3
根据地震地热说原理和中国西部的大地构造资料,讨论了青藏高原的地震构造活动模式及地震活动特征,认为兴都库什地震柱和缅甸地震柱是控制青藏高原构造运动和地震活动的主因,青藏高原深达70km的巨厚地壳是内陆地区壳内强震频发的有利构造条件,利用35km以下青藏高原的下地壳地震和周边地区的壳下地震活动动态,参考历史震例,可以为研究区内的壳内强震活动与火山活动提供可能的活动强度、活动地点及大致活动时段等前兆性指标,并取得了初步成效。利用地震柱概念对青藏高原地震构造活动模式的解释似乎更加贴近青藏高原的地震活动特征,可以更加合理地解释壳内强震或者火山发生的成因,也可以预测未来几年内地震柱及其影响区的活动趋势。 相似文献
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A systematic search was made for seismicity rate changes in the segment of the Kurile island arc from 45°N to 53°N by studying the cumulative seismicity of shallow (h100 km) earthquakes within 11 overlapping volumes of radius 100 km for the time period 1960 through beginning of 1978. We found that in most parts of this island arc and most of the time the seismicity rate as obtained from the NOAA catalogue and not excluding any events is fairly constant except for increased seismicity in the mid 1960s in the southern portion due to the great 1963 mainshock there, and for seismicity quiescence during part of the time period studied within two well defined sections of the arc. The first of these is a volume of 100 km radius around a 1973 (M
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=7.3) mainshock within which the seismicity rate was demonstrated at the 99% confidence level to have been lower by 50% during 2100 days (5.75 years) before this mainshock. The second volume of seismic quiescence coincides with the 400 km long north Kuriles gap. In this gap the seismicity rate is shown (at the 99% confidence level) to be lower by 50% from 1967 to present (1978), in comparison with the rate within the gap befor 1967, as well as with the rate surrounding the gap. We propose that the anomalously low seismicity rate within the Kuriles gap is a precursor to a great earthquake, the occurrence time of which was estimated by the following preliminary relation between precursory quiescence time and source dimensionT=190L
0.545. We predict that an earthquake with source length of 200–400 km (M>8) will occur along the north Kurile island arc between latitude 45.5°N and 49.2°N at a time between now and 1994. 相似文献
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由渤海周边地区地震台网记录的P波到时进行层析成像研究,得到了该地区地壳、上地幔速度图像的新信息.结果表明:1.渤海湾内地壳薄,是Moho面上隆的中心.2.渤张断裂由几段相接而成,属壳内断裂.3.该区岩石层厚度变化显著,渤海内为110km,燕山地区大于180km.渤海湾内上地幔盖层速度是研究区内最高的,最大值为8.45km/s,其岩石成分是高密度物质.这是该区呈现高重力异常的缘由.4.渤海内庙岛西部中地壳有一近似圆状的低速体,渤海内强震以及近期地震活动沿其周边展布,那里是高、低速块体的交界部位.研究区内其它地区的强震一般也发生在地壳中高速块体的边侧,或高速块体与低速块体的交界位置. 相似文献
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首先,我们利用现代非线性物理理论及震源理论建立了适合地震活动的逾渗模型。然后,我们利用这一模型,对辽宁地区１９７０年以来的地震活动进行了研究。通过对地震活动的逾渗相变过程中逾渗阈值附近的各种临界指数的计算,对破裂概率达到或超过逾渗阈值的子区域进行了讨论并对近期辽宁地区的地震活动趋势进行了探讨。 相似文献
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Restricted parts of the Valley of Mexico have been plagued by swarms of small earthquakes during recent years. The cause of these events is puzzling, but they may relate to massive artificial changes in the hydrology of the lake-bed which underlies most of Mexico City. If the valley responds elastically, plane strain finite element calculations can be used to relate geologic and seismic structure to observed seismicity and overall stability of the valley. These calculations show that unstable zones and areas of local seismicity coincide if the triggering mechanism of the seismicity is related to variations of pore pressure and water load.In order to make such a connection it is necessary to ascribe the generating mechanism of the seismicity to the density and elastic modulus anomalies associated with the valley structure, and to suggest that the phenomenon that triggers this seismicity is related to changes in water content of the near surface formations. 相似文献
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A newly developed clustering algorithm is described which uses the Unified Scaling Law for earthquakes to identify correlations between events that lead to clustering. This algorithm is applied to a dataset from the Hengill triple junction in south west Iceland to separate spatially and temporally overlapping earthquake sequences. We show that the algorithm successfully identifies spatio-temporally clustered events.A search for certain patterns in the identified clusters is performed. These patterns emerged in numerical simulations of seismicity performed by Hainzl (2003) when viscous coupling was introduced in order to reproduce features of swarm earthquakes. Namely we look for a combination of increased Gutenberg-Richter b-value and decreased exponent of the waiting-time distribution α. This pattern, indicating the strongest influence of viscous coupling on the characteristics of the seismicity, could be localized beneath an extinct volcano approximately 5 km north of an area of recent crustal uplift. 相似文献
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2016年12月—2018年4月间布设于汶川、芦山地震之间地震空段的密集监测台阵(LmsSGA)提供了密集的观测数据.通过拾取地震走时、初始定位,计算地方震级,得到了完备性震级为0级的地震目录.更加完备的地震目录为地震空段及周围地震活动的时空分布特征和孕震风险性评估提供了丰富的信息.重定位结果显示地震主要集中于龙门山断裂带深度为5～20km的孕震层内.地震活动频繁的汶川、芦山主震区,震源的空间分布模式与其早期余震相似,说明两次大地震的区域仍处于缓慢的应力调整阶段.青藏高原物质东向挤出受宝兴、彭灌杂岩阻挡,在两个杂岩体西北侧地震活动频繁.地震活动性分布显示汶川—茂县、映秀—北川断裂上存在一个清晰的长约30km,宽约20km的地震活动"空白"区域,与其下方因部分熔融而产生的低速体分布一致,我们推测熔融体的加温作用是导致空段内极低的地震活动性的主要原因.监测时段内仍观测到降雨变化率和地震数量呈反相关关系,再次证实了汶川—芦山地震间地震空段及邻区内季节性降雨对地震活动性存在一定调节作用.综合分析S波速度模型、历史强震活动及b值,我们推断地震空段东部的彭灌断裂中段及周围部分隐伏断层存在发生强震的风险. 相似文献
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— A seismic data file of 3,740 earthquakes from January 1987 to December 1994 has been elaborated for Morocco and the border regions, with 10 main events registering magnitudes from 5 to 5.6. Such seismicity is particularly important for Morocco as the released seismic energy constitutes a considerable part of the total energy radiated during the 20th century. Relative seismicity maps confirm the persistence of the major features of the seismicity of Morocco. An important seismic activity is observed in the Alboran region continental crust, which absorbs the maximum deformation resulting from the convergence of the African and Iberian plates. However, in the longitude window 3.5°– 6° W at depths of 25 to 50 km, a seismic gap zone seems to take place. An explanation of this phenomenon may be provided by the slab breakoff model. Even if the seismicity of Morocco remains moderate, heavy damage is observed when the magnitude of earthquakes exceeds 4.5, especially in the case of traditional buildings. 相似文献
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