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1.
It is proposed that some possible macroseismic epicenters can be determined quickly from the relationship that the microseismic epicenters located by instruments bear with faults.Based on these so-called macroseismic epicenters,we can make fast seismic hazard estimation after a shock by use of the empirical distribution model of seismic intensity.In comparison with the method that uses the microseismic epicenters directly,this approach can increase the preccision of fast seismic hazard estimation.Statistical analysis of 133 main earthquakes in China was made.The result shows that the deviation distance between the microseismic epicenter and macroseismic epicenter falls within the range of 35km for 88% earthquakes of the total and within the range of 35to 75km for the remaining ones.Then,we can take the area that has the microseismic epicenter as its center and is 35km in radius as the area for emphatic analysis,and take the area within 75km around the microseismic epicenter as the area for general analysis.The relation between the 66 earthquake cases on the N-S Seismic Belt in China and the spatial distribution characteristics of faults and the results of focal mechanism solution were analyzed in detail.We know from the analysis that the error of instrumental epicenter determination is not the only factor that gives effects to the deviation of the macroseismic epicenter.In addiditon to it,the fault size,fault distribution,fault activity,fault intersection types,earthquake magnitude,etc,are also main affecting factors.By sorting out ,processing and analyzing these affecting factors,the principle and procedures for quickly determining the possible position of the macroseismic epicenter were set up.Taking these as a basis and establishing a nationwide database of faults that contains relevant factors,it is possible to apply this method in practical fast estimation of seismic hazard. 相似文献
2.
Ground motion prediction equations (GMPE) in terms of macroseismic intensity are a prerequisite for intensity-based shake
maps and seismic hazard assessment and have the advantage of direct relation to earthquake damage and good data availability
also for historical events. In this study, we derive GMPE for macroseismic intensity for the Campania region in southern Italy.
This region is highly exposed to the seismic hazard related to the high seismicity with moderate- to large-magnitude earthquakes
in the Appenninic belt. The relations are based on physical considerations and are easy to implement for the user. The uncertainties
in earthquake source parameters are accounted for through a Monte Carlo approach and results are compared to those obtained
through a standard regression scheme. One relation takes into account the finite dimensions of the fault plane and describes
the site intensity as a function of Joyner–Boore distance. Additionally, a relation describing the intensity as a function
of epicentral distance is derived for implementation in cases where the dimensions of the fault plane are unknown. The relations
are based on an extensive dataset of macroseismic intensities for large earthquakes in the Campania region and are valid in
the magnitude range M
w = 6.3–7.0 for shallow crustal earthquakes. Results indicate that the uncertainties in earthquake source parameters are negligible
in comparison to the spread in the intensity data. The GMPE provide a good overall fit to historical earthquakes in the region
and can provide the intensities for a future earthquake within 1 intensity unit. 相似文献
3.
Earthquake parameters and spatial distribution of coseismic effects in Southern Siberia and Mongolia
In this work we review earthquakes that happened in Southern Siberia and Mongolia within the coordinates of 42°–62° N and 80°–124° E and first propose relationships between earthquake parameters (a surface-wave earthquake magnitude M s and an epicentral intensity(I 0) based on the MSK-64 scale) and maximal distances from an earthquake epicenter (R e max), hypocenter (R h max), and a seismogenic fault (R f max) to the localities of secondary coseismic effects. Special attention was paid to the study of these relationships for the effects of soil liquefaction. Hence, it was shown that secondary deformations from an earthquake were distributed in space away from an earthquake epicenter, than from an associating seismogenic fault. The effects of soil liquefaction are manifested by several times closer to a seismogenic fault, than all other effects, regardless of the type of tectonic movement in a seismic focus. Within the 40 km zone from an earthquake epicenter 44% of the known manifestations of liquefaction process occurred; within the 40 km zone from a seismogenic fault—90%. We propose the next relationship for effects of soil liquefaction: M s = 0.007 × R e max + 5.168 that increases the limits of the maximum epicentral distance at an earthquake magnitude of 5.2 ≤ M s ≤ 8.1 as compared to the corresponding relationships for different regions of the world. 相似文献
4.
探讨地震宏观破坏场分布的影响因素 总被引：3，自引：0，他引：3
提出震后根据仪器定位的微观震中和断层构造的关系快速确定可能的宏观震中位置,并依此使用烈度经验分布模型来进行震害快速评估。这将提高直接用微观震中位置进行震害快速评估方法的精度。通过对全国133个主要地震的微观震中与宏观震中偏离量进行统计可知。偏离量在35km范围内的占88％,其余基本都在75km范围内。这样就给出了判定宏观震中的重点区域和分析区域。详细分析南北地震带66个震例及其与断层空间分布特征的关系。以及震源机制解结果后发现,影响宏观震中偏离的因素除仪器定位本身的误差外,主要还有断层展布方向、活动规模、断层相互交接特征及震级大小等。通过对这些影响因素的分类处理分析,建立了震后室内快速判定可能的宏观震中位置的原则和步骤。以该方法为基础,通过建立包含有关因素的全国断层数据库,即可在实际的震害快速评估中得以应用。 相似文献
5.
The seismic risk analysis evaluation in the Mediterranean area is one of the main tasks for the preservation of Cultural Heritage and for the sustainable development of Mediterranean cities. The Mediterranean area is characterised by a medium–high level of seismic risk, so that earthquakes are the major cause for the destruction of monuments, residential and industrial buildings. A case history regarding the seismic risk analysis for the city of Catania (Italy) is presented, since the city has been heavy damaged in the past by strong earthquakes such as the 1169 earthquake (XI MCS), the 1542 earthquake (IX MCS), the 1693 earthquake (XI MCS) and the 1818 earthquake (VIII MCS) etc., which caused several thousands of deaths. Fault modelling, attenuation laws, synthetic accelerograms, recorded accelerograms and site effects are considered for the evaluation of the seismic action. Vulnerability of physical environment, related to the presence of cavities and to seismic-induced landslides and liquefaction has been analysed, with special reference to the new modelling of such phenomena and to the application of models to given areas. Soil–structure Interaction has been analysed for some geotechnical works, such as shallow foundation and retaining wall, by means of physical and numerical modelling. The paper deals with the vulnerability of physical environment (landslides, liquefaction, etc.), while the road map continues with the analysis of vulnerability of monuments and buildings, with the aim of the estimation of the seismic resistance required to defend against the seismic action given by the scenario earthquake. For the mitigation of seismic risk, structural improvements of R.C. buildings with different methodology and techniques have been analysed, as well as the guideline for the strengthening of buildings. The work shows that the seismic risk of the city is not a summation of the seismic risk of each building, because the vulnerability of the urban system plays an important role on the seismic risk evaluation of a given city. To this aim the vulnerability of the road infrastructures, lifelines, and urban framework have been also analysed in the project. 相似文献
6.
综合活动构造与重要活动断裂带的历史及现今强震震源区或破裂分布等资料,南北地震带北段存在长期缺少MSge;7.0地震的破裂空段．为了考察这些空段的地震危险性,首先采用Burgers体黏弹介质模型,计算周围有记载以来的历史强震在空段引起的库仑应力动态演化;其次结合背景地震发生率,采用Dieterich模型分析历史强震对空段地震活动的影响,讨论了空段所在区域的地震发生概率．结果显示,南北地震带北段强震破裂空段的地震危险性程度自高到低依次是:东昆仑活动断裂带东段的若尔盖——九寨沟段、六盘山断裂带中南段空段、香山——天景山段裂中南段同心空段、天祝——大靖空段、西秦岭北缘断裂带中西段、西秦岭北缘断裂带东段．该结果可为南北地震带北段的地震危险性估计提供参考． 相似文献
7.
A disastrous earthquake with a magnitude M
S
= 8.0 (M
W
= 7.9), in China called “the 5.12 Wenchuan earthquake,” occurred on May 12, 2008, in Sichuan province on the border between
the Sino-Tibetan Mountains and the Sichuan depression. The instrumental epicenter was registered in the southeastern part
of Wenchuan county, and the hypocenter depth was 14 km. As the strongest and most destructive earthquake within mainland China,
it caused numerous human losses and destruction of buildings and infrastructure. The seismic effect from the main shock and
aftershocks was felt in many counties, towns, and villages, though Sichuan province suffered the most. The maximum intensity
of the shocks was estimated at 11 degrees, according to the Chinese macroseismic scale. In the process of source opening,
from the southern part of Wenchuan county to the vicinities of Quingchuan, a seismic fault system with a total length up to
240 km out-cropped on the earth’s surface, confined to the Longmenshan fault belt. The seismic fault system disturbed the
original ground, resulting in the collapse or damage to various constructions, such as buildings, homes, bridges, roads, etc.
Fault offsets had a dextral strike-slip and thrust kinematic combination. The earthquake generated several tens of thousands
of landslides, rockfalls, and debris flows. Many dammed ponds appeared in the epicentral zone due to the activation of landslides.
Thus, the geological effects turned out to be the most destructive factor in this case. At the same time, the seismic intensity
of surface shaking was abnormally low even in direct proximity to the seismic fault system. Usually it was no more than 7–8
degrees. This macroseismic phenomenon may turn out to be rather typical for many major earthquakes. 相似文献
8.
首先对2017年九寨沟MS7.0地震周边断裂活动和历史地震特征进行了阐述;然后利用黏弹性地壳模型,计算了1933年叠溪地震、1976年松潘震群和2008年汶川地震对2017年九寨沟地震的同震和震后库仑应力作用.该结果显示1933年叠溪地震对九寨沟地震具有延缓作用,而1976年松潘震群和2008年汶川地震对九寨沟地震的黏弹性库仑应力作用为正;随着下地壳和上地幔黏弹性物质的持续作用,前述几次地震总的黏弹性库仑应力在九寨沟地震破裂中心点处负的库仑应力逐渐减弱,而在破裂北段这些库仑应力逐渐转为正值,并促进了九寨沟地震的发生.本文也计算了九寨沟地震后对周边断层的库仑影响,并将此影响值转换为对断层能量积累的影响时间上,结果显示塔藏断裂带西段和中段在内的多条断裂带受到黏弹性库仑应力影响时间值超过10年.将库仑应力影响时间值加入到部分已知离逝时间的断层段上,也得到了这些断层段的未来30年特征地震发生概率.最终结果认为玛沁断裂带、玛曲断裂带、哈南—稻畦子断裂中段和西段等断层段的强震危险性需要重点关注. 相似文献
9.
探讨了断层间相互作用产生的同震库仑应力改变及对地震的触发与延缓效应，并以鲜水河断裂带不同断裂段时间上连续发生的4次MS6.0以上地震为例，计算和分析了每次地震发生后，在周围其它断裂上产生的同震库仑应力改变及其对后续地震的触发，以及1973年炉霍MS7.6地震和1981年道孚MS6.9地震发生后，在其周围最易破坏失稳的微破裂上产生的同震库仑应力改变及对余震活动的影响．在其它条件保持不变的情况下，将这4次地震的累积触震与缓震效应加以定量考虑，对鲜水河断裂带各断裂段的地震潜势进行了重新计算，并与已有预测结果进行对比分析，检验和评估了鲜水河断裂带断层间相互作用触震与缓震效应的重要性．结果表明:鲜水河断裂带每次地震都发生于受其先前发生的地震影响而产生同震库仑应力增加的断裂段上，不同断层间相互作用的触震和缓震效应导致地震复发概率的改变可高达30.5％以上， 主震后的余震大多发生于同震库仑应力增加较高的微破裂上． 相似文献
10.
《地震研究进展（英文）》2023,3(1):100172
Timely response to earthquake characterization can facilitate earthquake emergency rescue and further scientific investigations. On June 1, 2022, MW 5.9 earthquake occurred in the southern area of the Longmenshan fault zone. This event also happened at the south end of the Dayi seismic gap and is the largest earthquake that has occurred in this seismic gap since the 1970 M 6.2 event. The slip-distribution model constrained by the seismic waveforms suggests a thrust-dominated faulting mechanism. The main slip occurs at a depth of ～14 ?km, and the cumulative energy is released in the first 6 ?s. The variations of Coulomb stress caused by the mainshock show a positive change in the southwest area of the Dayi seismic gap, indicating possible activation of future earthquakes. In addition, we emphasize the importance of rapid estimation of deformation for near-field hazard delineation, especially when interferometric radar fails to image coseismic deformation in a high relief terrain. 相似文献
11.
地震滑坡的滑距与重力滑坡的滑距有着显著的不同,科学预测地震发生时黄土地区滑坡的滑动距离是合理评估黄土地区滑坡风险和减轻滑坡灾害的有效方式之一。基于海原特大地震诱发黄土滑坡的400组野外调查数据,通过引入BP神经网络算法,论证了BP神经网络模型用于预测黄土地震滑坡滑距的适宜性和可行性;建立了地震诱发黄土滑坡滑距的BP神经网络预测模型,并通过67组数据进行了验证。BP神经网络算法和传统多元线性回归、多元非线性回归结果的对比显示,BP神经网络的预测更接近真实情况,具有较为理想的预测效果,可以用于黄土地震滑坡滑距的预测,并为圈定较为可靠的致灾范围提供依据。 相似文献
12.
The coseismic Coulomb stress change caused by fault interaction and its influences on the triggering and delaying of earthquake are briefly discussed.The Xianshuihe fault belt consists of Luhuo,Daofu,Kangding,Qianning and Ganzi fault.Luohuo(Ms=7.6,1973)-Kangding(Ms=6.2,1975)-Daofu(Ms=6.9,1981)-Ms=6.0,1982)earthquake is a seismic sequence continuous on the time axis with magnitude greater than6.0.They occurred on the Luhuo.Kangding,Daofu and Ganzi fault,respectively.The coseismic Coulomb stress changes caused by each earthquake on its surrounding major faults and microcracks are calculated,and their effects on the triggering and delaying of the next earthquake and aftershocks are analyzed.It is shown that each earthquake of the sequence occurred on the fault segment with coseismic Coulomb stress increases caused by its predecessors,and most after-shocks are distributed along the microcracks with relatively larger coseismic Coulomb stress increases resulted from the main shock.With the fault interaction considered,the seismic potential of each segment along Xianshuihe fault belt is reassessed,and contrasted with those predicted results ignoring coseismic Coulomb stress change,the significance of fault interaction and its effect on triggering and delaying of earthquake are emphasized.It is con-cluded that fault interaction plays a very important role on seismic potential of Xianshuihe fault belt,and the maximal change of future earthquake probability on fault segment is up to 30.5%. 相似文献
13.
14.
A destructive earthquake of magnitude Mw = 6.8 hit the region of Boumerdes and Algiers (Algeria) on May 21, 2003. This is among the strongest seismic events of the mediterranean region and the most important event in the capital Algiers since 1716. It caused a widespread damage in the epicentral region, claimed 2271 human lives, injured 10000, about 20000 housing units affected and left about 160000 homeless. The main shock was felt about 250 km far from the epicenter and triggered sea waves of 1–3 m in amplitude in Balearic islands (Spain). Based on field observations and press report an intensity IX (MSK scale) is attributed to the epicentral area. The main shock was followed by many aftershocks among them several are of magnitude greater than 5.0, which added panic to inhabitants. The main shock triggered ground deformation, particularly liquefaction whose features are in different forms and sizes and caused damage and collapse of roads. The focal mechanism determined by worldwide institutions yield a pure reverse faulting with a compressional axis striking NE-SW. The epicenter is located offshore about 7 km from the Boumerdes-Dellys coast. Field observations show 0.7 m of coseismic uplift of shoreline between Boudouaou and Dellys. This uplift is about a half of the extracted coseismic slip from the seismic moment. On the other hand there is no clear surface break onshore, confirming hence, that the causative active fault is offshore. However, the rupture may propagate onshore to the SE near the Boudouaou region where ground cracks showing reverse faulting are observed a long a corridor of about 1 km wide. These fissures may correspond to a diffuse coseismic deformation. 相似文献
15.
16.
系统梳理了2000年以来山西地区6次MS≥4.5地震前地震活动异常,结果表明,地震空区/平静、地震条带、显著地震/震群、大同地震窗“开窗”活动等异常在地震发生前具有一定普遍性,且异常基本围绕在震中及附近地区分布,特别是在地震平静/空区、地震条带等异常发展后期出现的显著地震/震群活动,对未来地震发生的地点和时间具有较好的预测意义。异常持续时间与发震间隔统计表明：异常多出现在主震发生前6个月以内,显著地震/震群、大同地震窗“开窗”对未来主震的发生具有短临预测意义。此外,随着区域应力水平的不断增强,在特定敏感地区会发生成组极微震密集活动,监视跟踪这些有别于正常活动背景的极微震活动,对地震短临预测具有一定意义。 相似文献
17.
越来越多的地震滑坡相对于地震断层的不对称分布震例让人们意识到断层上盘效应的存在。 然而,目前有关断裂运动方式与滑坡空间分布关系的研究还不够充分和深入。在收集大量地震滑坡震例资料并获得其分布规律的基础上,建立了一个简化的断层模型,以地震波在地表与断层面之间反射传播特性为基础,探讨断层倾角改变对地表地震动强度的影响。进而,以汶川地震触发的大型滑坡为例,研究了断层的几何特征和运动方式对诱发滑坡空间分布的影响。结果表明,断层的倾角对滑坡空间分布范围具有控制作用,随着倾角的增加,垂直断层走向的滑坡分布范围逐渐减小;并且,大型滑坡的初始坡面受到断裂运动方向的影响,与断裂运动方向一致的坡面更容易发生滑坡。所获结果不仅有助于提高区域性地震滑坡危险区域的预测精度,而且对认识大型滑坡的滑动机制、主控因素以及可能的滑动规模、滑距等也起到促进作用。通过对滑坡崩塌的认识来辅助提高对地质构造、地震断层等的认识,应是地震诱发滑坡崩塌研究的新的意义所在。 相似文献
18.
利用区域台网地震资料, 分析了川西安宁河-则木河断裂带不同段落的现今活动习性，进而鉴别潜在大地震危险的断裂段. 文中由异常低b值的分布圈绘出凹凸体，发展和应用了由多个地震活动参数值的组合判定断裂分段活动习性的方法，尝试了利用凹凸体段的震级频度关系参数估计特征地震的平均复发间隔. 结果表明，该研究断裂带存在5个不同现今活动习性的段落. 其中，安宁河断裂的冕宁-西昌段属于高应力下的闭锁段，其核心部分为一较大尺度的凹凸体；则木河断裂的西昌-普格段则表现为低应力下的微弱活动状态. 重新定位的震源深度分布，显示出上述闭锁段和微弱活动段的断层面轮廓. 冕宁-西昌段是未来大地震的潜在危险段. 该段从最晚的1952年6.7级地震起算，至未来特征地震的平均复发间隔估值为55～67年, 未来地震的震级估值为7.0～7.5. 本研究也初步表明，同-断裂段的活动习性可随时间动态演变. 相似文献
19.
COULOMB STRESS EVOLUTION AND SEISMIC HAZARD ALONG THE EASTERN BOUNDARY OF THE SICHUAN-YUNNAN BLOCK 
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下载免费PDF全文 Using a more realistic model of multi-layered viscoelastic media, and considering the effects of the coseismic dislocation and the postseismic viscoelastic relaxation caused by the 34 great earthquakes occurring along the eastern boundary of the Sichuan-Yunnan block since 1480 and the interseismic stress accumulation caused by the tectonic loading generated by plate motions which were modeled by introducing "virtual negative displacements" along the major fault segment in the region under study, we calculated the evolution of the Coulomb stress change in each fault plane of 18 major fault segments along the eastern boundary caused by the coseismic, postseismic and interseismic effects. We studied the interactions of the Xianshuihe, Anninghe, Zemuhe and Xiaojiang fault zones on the eastern boundary of the Sichuan-Yunnan block. By evaluating if the previous earthquake could bring another earthquake closer to or farther from failure, we analyzed the interactions of the earthquakes which occurred in the different segments in the same fault zone, or in the different fault zones respectively. And further based on the calculation results of the Coulomb stress change on the fault planes, we analyzed the seismic hazard of each fault segment.The results show that the previous earthquake may trigger another earthquake which can occur in the same fault zone or in the different fault zone. And the calculation results on the evolution of the cumulative Coulomb stress change in the each fault segment show that, the Coulomb stress increases significantly in the middle section and the Moxi segment of the Xianshuihe fault zone, the Mianning-Xichang segment of the Anninghe fault zone, the Qiaojia-dongchuan segment and the Jianshui segment of the Xiaojiang fault zone, and the seismic hazard in these fault segments is worthy paying attention to. 相似文献
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2020年2月3日四川省成都市青白江区发生MS5.1地震,震中烈度为Ⅵ度。该地震事件震中位于龙泉山断裂带上,距离成都市中心38 km,是龙泉山断裂带历史上非常罕见的5.0级以上地震事件。针对该事件成因进行了综合分析与研究,具体内容包括:(1)通过收集历史地震资料讨论龙泉山断裂带的地震活动性;(2)利用高质量的波形数据对主震位置进行重定位;(3)根据地震层析成像获得的三维vP、vS以及泊松比(σ)模型分析了孕震构造和流体影响,以及(4)利用固体潮理论模型分析了固体潮与地震触发的相关性。结果表明,本次MS5.1地震发生在龙泉山断裂带北段,震中坐标为(30.732°N,104.529°E),震源深度为15.12 km;震源位于高-低泊松比过渡带附近,并伴随着大范围的低速异常,初步推断与深部流体有关;同时,固体潮在断层面上产生的剪切应力变化,也可能与本次地震的触发密切相关,暗示着在地震发生前龙泉山北段的地震危险性已经达到了较高水平。因此深部流体侵入作用、强震同震效应以及特定孕震构造环境的综合影响可能是导致本次地震触发的主要因素。 相似文献