共查询到20条相似文献，搜索用时 15 毫秒
1.
This study presents the future seismic hazard map of Coimbatore city, India, by considering rupture phenomenon. Seismotectonic
map for Coimbatore has been generated using past earthquakes and seismic sources within 300 km radius around the city. The
region experienced a largest earthquake of moment magnitude 6.3 in 1900. Available earthquakes are divided into two categories:
one includes events having moment magnitude of 5.0 and above, i.e., damaging earthquakes in the region and the other includes
the remaining, i.e., minor earthquakes. Subsurface rupture character of the region has been established by considering the
damaging earthquakes and total length of seismic source. Magnitudes of each source are estimated by assuming the subsurface
rupture length in terms of percentage of total length of sources and matched with reported earthquake. Estimated magnitudes
match well with the reported earthquakes for a RLD of 5.2% of the total length of source. Zone of influence circles is also
marked in the seismotectonic map by considering subsurface rupture length of fault associated with these earthquakes. As earthquakes
relive strain energy that builds up on faults, it is assumed that all the earthquakes close to damaging earthquake have released
the entire strain energy and it would take some time for the rebuilding of strain energy to cause a similar earthquake in
the same location/fault. Area free from influence circles has potential for future earthquake, if there is seismogenic source
and minor earthquake in the last 20 years. Based on this rupture phenomenon, eight probable locations have been identified
and these locations might have the potential for the future earthquakes. Characteristic earthquake moment magnitude (M
w
) of 6.4 is estimated for the seismic study area considering seismic sources close to probable zones and 15% increased regional
rupture character. The city is divided into several grid points at spacing of 0.01° and the peak ground acceleration (PGA)
due to each probable earthquake is calculated at every grid point in city by using the regional attenuation model. The maximum
of all these eight PGAs is taken for each grid point and the final PGA map is arrived. This map is compared to the PGA map
developed based on the conventional deterministic seismic hazard analysis (DSHA) approach. The probable future rupture earthquakes
gave less PGA than that of DSHA approach. The occurrence of any earthquake may be expected in near future in these eight zones,
as these eight places have been experiencing minor earthquakes and are located in well-defined seismogenic sources. 相似文献
2.
3.
汶川MS8.0级地震、芦山MS7.0级地震和鲁甸MS6.5级地震均引发了大量的滑坡灾害。由于震级差异和地质地形条件的不同,地震滑坡分布情况有较大区别。本文综合已有的研究成果,从地震、地质和地貌3个方面,对比分析了地震滑坡的分布规律。结果表明:（1）3次地震滑坡数量和密度随着PGA和震级的增加而增加。汶川和鲁甸地震随烈度的增加,滑坡数量呈现递增的趋势。但芦山地震在较低烈度区也发育着大量滑坡。（2）断层影响滑坡分布的最大距离随着震级的增加而增加。在最大影响距离0.2倍的范围内,汶川地震分布有80%的滑坡,而其他两次地震仅30%。此外,汶川地震滑坡数量随断层距离呈指数衰减关系。（3）地震滑坡的分布受到地形的强烈影响。Ⅶ度及以上烈度区地形切割深度越大,地震触发的滑坡集中分布区域相对高差越大。同时,滑坡集中发育的坡度会随之增加。切割深度越大,地震滑坡更易发生在地势较陡的山脊或者上坡处,这可能与地形放大效应有关。 相似文献
4.
Earthquake losses due to ground failure 总被引：2，自引：0，他引：2
Juliet F. Bird 《Engineering Geology》2004,75(2):147-179
Ground shaking is widely considered to be the primary cause of damage to structures, loss of life and injuries due to earthquakes. Nonetheless, there are numerous examples of earthquakes where the losses due to earthquake-induced ground failure have been significant. Whereas ground shaking causes structural and non-structural damage, with associated loss of function and income, ground failure is less likely to cause spectacular structural collapses, but is frequently the cause of major disruptions, particularly to lifelines, which can lead to prolonged loss of function and income, even for undamaged areas.Those involved in earthquake loss modelling are currently presented with three choices with respect to the incorporation of ground failure: they can choose to ignore it, assuming that any estimation of losses caused by shaking would effectively subsume the impact of these secondary hazards; they can include ground failure in a simple manner, using published approaches based upon qualitative data and a large degree of judgement; or, they can opt for a detailed site- or region-specific assessment of damage due to ground failure, with the associated time and expense.This paper presents a summary of the principal features of earthquake losses incurred in damaging earthquakes over the last 15 years. Survey data are impartially analysed, considering both ground failure and ground shaking as sources of damage, and their relative contribution to overall damage in each section of the regional infrastructure is presented. There are many other variables influencing these contributions, including the size of the earthquake, the economic status of the affected region, local geology and terrain and the building stock, which have been considered.The findings of the study are discussed from the point of view of loss modelling and which components of a model should merit the most time and resource allocation. The general assumption that ground shaking is the principal cause of damage and loss is strongly supported by the study. However, there are a number of scenarios identified where the failure to appropriately include the effects of ground failure would lead to unrealistic loss projections. Such scenarios include the assessment of building losses in small zones rather than on a regional basis, and the incorporation of lifeline damage or disruption and indirect losses into a model. 相似文献
5.
Estimation of seismic hazard in Gujarat region, India 总被引：1，自引：1，他引：0
Sumer Chopra Dinesh Kumar B. K. Rastogi Pallabee Choudhury R. B. S. Yadav 《Natural Hazards》2013,65(2):1157-1178
The seismic hazard in the Gujarat region has been evaluated. The scenario hazard maps showing the spatial distribution of various parameters like peak ground acceleration, characteristics site frequency and spectral acceleration for different periods have been presented. These parameters have been extracted from the simulated earthquake strong ground motions. The expected damage to buildings from future large earthquakes in Gujarat region has been estimated. It has been observed that the seismic hazard of Kachchh region is more in comparison with Saurashtra and mainland. All the cities of Kachchh can expect peak acceleration in excess of 500?cm/s2 at surface in case of future large earthquakes from major faults in Kachchh region. The cities of Saurashtra can expect accelerations of less than 200?cm/s2 at surface. The mainland Gujarat is having the lowest seismic hazard as compared with other two regions of Gujarat. The expected accelerations are less than 50?cm/s2 at most of the places. The single- and double-story buildings in Kachchh region are at highest risk as they can expect large accelerations corresponding to natural periods of such small structures. Such structures are relatively safe in mainland region. The buildings of 3?C4 stories and tall structures that exist mostly in cities of Saurashtra and mainland can expect accelerations in excess of 100?cm/s2 during a large earthquake in Kachchh region. It has been found that a total of 0.11 million buildings in Rajkot taluka of Saurashtra are vulnerable to total damage. In Kachchh region, 0.37 million buildings are vulnerable. Most vulnerable talukas are Bhuj, Anjar, Rapar, Bhachau, and Mandvi in Kachchh district and Rajkot, Junagadh, Jamnagar, Surendernagar and Porbandar in Saurashtra. In mainland region, buildings in Bharuch taluka are more vulnerable due to proximity to active Narmada-Son geo-fracture. The scenario hazard maps presented in this study for moderate as well as large earthquakes in the region may be used to augment the information available in the probabilistic seismic hazard maps of the region. 相似文献
6.
The January 25, 1946 earthquake in the central Valais region in southwest Switzerland was the strongest for the last 150 years.
It reached an epicentral intensity Io of VIII in the area of Sierre. The Swiss Earthquake Catalogue (ECOS 2002) assigns a
moment magnitude of Mw = 6.1 to the event. Assessment of recordings from European stations resulted in a moment magnitude
of 5.8 (Bernardi et al. 2005). The earthquake caused moderate to high damage within a circle of about a 25 kilometer radius.
Slight damage occurred up to a distance of 200 kilometers from the epicenter.
The goal of this study was to reconstruct the damage field and consider its possible site-effects. We used an approach combining
historical research with seismo-/geological investigation including a large number of experiments measuring the fundamental
frequency of resonance and the shear-wave velocities of the sedimentary layers, using the characteristics of ambient vibration.
This kind of research is relevant, since a huge alpine valley characterizes the Valais region, showing ground conditions that
make site-effects likely for earthquakes. While we searched for damage in an unlimited area, our investigation of site-effects
was limited to the Rhone valley and to Sion and Sierre in the central Valais region in particular. 相似文献
7.
火山喷发过程所伴生的地震活动会诱发大量的崩塌滑坡次生灾害,其所造成的人员财产损失甚至超过火山活动本身。2002年以来长白山天池火山区地震活动的异常,表明火山深部的岩浆正在发生变化,天池火山存在喷发的危险。地震崩塌滑坡的危险性区划是降低生命财产损失的有效手段。将火山伴生地震作为崩塌滑坡灾害的诱发因素并据此设置地震参数,利用简化的Newmark累积位移模型,考虑地形因素对地震的放大效应,对长白山地区天池火山喷发下次生崩塌、滑坡灾害的危险性进行评价。通过探讨不同地震震级下的危险性分区结果,认为不同地震参数的设置对危险性分区结果没有影响。将研究区划分为极高、高、中等、低、极低等5个危险等级,其中,极高危险区主要分布在3个区域:以天池口为中心,40km为半径的范围内;沿江乡—两江镇—松江镇条带区域;长白县境内鸭绿江沿岸区域。 相似文献
8.
9.
Although earthquakes are thought to be one of the factors responsible for the occurrence of landslides in Hokkaido, there
exist no enough records which can allow correlating many of the old slope failures in the island with earthquakes. In the
absence of these records, an attempt was done in this study to use the abundance, frequency, magnitude, depth, and distribution
of historical earthquakes to deduce that many of the slope failures in the region were triggered by strong and continuous
seismicity. The determination of the zones of influences of selected earthquakes using an existing empirical function has
also supported this conclusion. Moreover, the use of a 10% probability of exceedance of earthquake intensity in 50 years,
and the geological and slope maps has allowed preparing a landslide hazard map which explains the role of future earthquakes
in the formation of slope failures. The result indicates a high probability of occurrences of landslides in the hilly regions
of the southeastern part of Hokkaido due to expected strong seismicity and earthquake intensities in these areas. On the other
hand, the low level of intensity in the north has given rise to low probability of landslide hazard. There are also places
in the center of the island and high intensity regions in the east where the probability of landslide hazard was influenced
by the contribution of the geological and slope maps. 相似文献
10.
Earthquakes occurring during the night or early morning hours cause a heavy loss of life. Also, an earthquake occurring in the late evening hours poses serious handicap for disaster mitigation efforts due to failure of electricity and blocking of roads due to fall of debris. The larger aftershocks may cause further damage depending upon the magnitude of the main earthquakes of magnitude 5.5 and more in the Indian region. Out of 7 great earthquakes (M >7.8) in the Indian region during the last 200 years, five (1819, 1897, 1905, 1941 and 1950) have occurred during the evening or early morning hours. About 67% of all the earthquakes of magnitude >7.0 show similar result. It is found that in general, the percentage of earthquakes occurring during evening/early morning is larger than that during the daytime. However, the difference in time of occurrence is not significant at 95% level of confidence using 2 test. Keeping in view that most of the earthquakes in India of magnitude more than 6 have caused significant damage in the last decade (Uttarkashi, 1991; Latur, 1993; Jabalpur, 1997; Chamoli, 1999) and have occurred in the night/ early morning, disaster management plans need to be designed for awareness and education separately for the night and day times.The limitations of the seismic zoning map with reference to the earthquakes in Koyna (1967) and Latur (1993) have suggested to safeguard the life and property of the Indian population from the effects of future damaging earthquakes which should be failsafe instead of following the code and then introduce further changes in the code. It is suggested that residential houses (including tall structures) should be built for a design earthquake of magnitude 6.0 in all the three seismic zones namely I, II and III demarcated by the Bureau of Indian Standards giving proper weight age to site response. However, for Zones IV and V usual code recommendations may be followed through micro zoning of important, densely populated or most vulnerable areas. 相似文献
11.
地表调查发现, 沿近南北向亚东-谷露裂谷中段的安岗地堑存在地震大滑坡、多世代断层崖和断层崩积楔等多种类型的史前大地震遗迹.进一步的观测和年代分析表明: 该区的古地震滑坡体至少存在新、老两期, 其中规模最大的"尼续大滑坡体"应该是最新一次大地震所形成.该区T1到T6各阶地的形成时代从新到老分别为7.7~2.1 ka、11.0~10.5 ka、17.6~12.1 ka、25.7~22.9 ka、58.4~70.6 ka和130~150 ka, 它们沿主边界正断层的平均垂直断距依次为2.8 m、6.1~7.9 m、10.3~12.5 m、16.6~19.0 m、28.0 m和76.0 m.其中T1和T2阶地上的断崖剖面揭示, 最近两次大地震发生在距今约5.8±1.0 ka和2.4±0.2 ka.综合分析认为: 安岗地堑的大地震活动具有较明显的丛集性特征, 并且在距今约23~26 ka以来一直处于大地震活跃期, 期间的断层垂直活动速率为0.8~1.3 mm/a, 大地震的原地复发间隔大致为3.3~3.6 ka, 特征地震的矩震级为7.0~7.2, 推算整个尼木地堑群的大震复发间隔最短可能只有约1.0~1.2 ka.研究结果指示, 藏南裂谷的大地震活动性明显比藏北的近南北向正断层更显著. 相似文献
12.
N.N. Ambraseys 《地学学报》1991,3(2):202-211
We reappraised the Rukwa earthquake of 1910 in the East African Rift System. With a magnitude of 7.4, no earthquake in East Africa is known to be larger and it is rivalled only by the recent earthquake in southern Sudan on 20 May 1990. More than 80 per cent of the moment release in the Rift during the last 110 years is due to the Rukwa earthquake and its aftershocks that occurred between the Tanganyka and Nyasa systems. In spite of its large magnitude, the Rukwa earthquake caused very little damage to local types of dwellings and no loss of life. With increasing development of urban areas with modern types of houses, there is now increasing risk in East Africa from major earthquakes. 相似文献
13.
地震崩滑预测方法及其工程应用研究 总被引：24，自引：1，他引：23
在对我国已有地震崩塌和滑坡资料 (简称崩滑 )的研究分析基础上 ,提出适用于我国西部地区地震崩滑的由粗至细、分级预测地震崩滑的方法。 1 )建立地震崩滑最大震中距 ( Rm)与地震震级 ( Ms)间关系的初判准则 ;2 )综合考虑岩性、结构类型、地形、气象、地震等因素对地震崩滑的共同作用 ,并对不同因素的主次作用进行区分和量化 ,建立预测地震崩滑的再判准则。并用 1 996年 2月 3日丽江 7.0级地震引发的地震崩塌和滑坡实例对此预测方法进行了验证。 相似文献
14.
Seismic hazard maps are constructed by extrapolating from the frequency of small earthquakes, the annual probability of large, infrequent, earthquakes. Combining the potential contribution from all seismically active volumes, one calculates the peak ground acceleration with a probability to be exceeded by 10?% in 50?years at any given point. The consequential risk, the losses to be expected, derives from the damage the calculated shaking causes to buildings, and the impact on occupants due to collapsing structures. We show that the numbers of fatalities in recent disastrous earthquakes were underestimated by the world seismic hazard maps by approximately two to three orders of magnitude. Thus, seismic hazard maps based on the standard method cannot be used to estimate the risk to which the population is exposed due to large earthquakes. 相似文献
15.
The earthquake is known to be an unpredictable geophysical phenomenon. Only few seismic indicators and assumptions of earthquakes can be predicted with probable certainty. This study attempts to analyze the earthquakes over the Indo-Himalayan Border region including Bhutan, Bangladesh, Nepal, China and India during the period from 1995 to 2015. Bangladesh, Bhutan and China borders experience fewer earthquakes than Nepal and India border regions. However, Indo-China rim has inconsistency and vast range in its magnitude. Bangladesh though is a small country with respect to others, but it experiences earthquakes comparable to Bhutan. Nepal experiences highest number of earthquakes. In the last 20 years around 800 records have been observed with moment magnitude > 4.0 Richter scale, while very few records (around 10–12) have been observed for large earthquakes having moment magnitude > 6.0 Richter scale over the region. In this study adaptive neuro-fuzzy inference system has been implemented to assess the predictability of seismic moment associated with large earthquakes having the moment magnitude between 6.0 and 8.0 Richter scales using different combination of epochs, technique and membership functions. The Gaussian membership function with hybrid technique and 40 epochs is observed to be the reasonable model on the basis of the selected spatial and temporal scale. The forecast error in terms of root-mean-square error with the stopping criterion 0.001 has been observed to be 0.006 in case of large earthquakes (> 6.5 Richter scale), that is, forecast accuracy of 99.4%. The model bias of 0.6% may be due to inadequate number of large earthquakes having moment magnitude > 6.5 Richter scale over the region. 相似文献
16.
On far field occurrence of seismically induced landslides 总被引：1，自引：0，他引：1
Earthquakes may induce landslides at large distances from the epicentral area. In the last two decades, there have been many studies of this phenomenon to determine the causes that contribute to the occurrence of landslides at very long distances from earthquake epicenter. In this study, which is based on previously published works, a worldwide database comprising 270 earthquakes, including 150 during the instrumental period, was compiled to analyse the features of those landslides that occur at much further distances than maximum expected distances. From the analysis of the compiled data, it was observed that susceptible slopes can be grouped into five broad geological categories: jointed rock, marly–clayey (cohesive) soils, granular alluvial and/or colluvial sediments, volcanic soils, and residual soil slopes. These categories were equally likely to be associated with far field disrupted landslides, whereas far field coherent landslides were more frequent on cohesive soil slopes. Other factors, along with slope susceptibility may also contribute to far field landslides and increase the size of the area affected. Among these factors, site effects, antecedent rain and occurrence of seismic series have been cited. The analysis of available data also showed that for events of the same magnitude, far field disrupted landslides may occur at greater distances than coherent ones. The same database has also been employed to determine, for the first time, the upper bound curves for the maximum observed epicentral distances of several types of landslides and the maximum area observed to be affected by landslides, both based on the epicentral intensity of the events. 相似文献
17.
极震区岩体地震动力破坏若干问题探讨 总被引：2，自引：0，他引：2
汶川地震时极震区产生了严重的地震地质灾害,其中强烈地震动造成的岩体动力破坏是造成灾害的根本原因。从极震区含义、地震动特征、岩体地震动力破坏概念、地震松动岩体和方法论等方面初步探讨了极震区岩体地震动力破坏问题。极震区是未来地震的潜在震源区,区内的地震属于直下型。极震区地震动具有不同于非极震区的地震动特征,岩体地震动力破坏的复合性特点就是地震动的不确定性造成的。对极震区岩体动力破坏概念的理解应考虑地震动的特点。地震松动岩体是极震区地震动造成的一种特殊破坏类型,是形成震害次生灾害的重要原因。岩体工程地质力学等学科的思想方法和技术手段为研究极震区岩体地震动力破坏这一命题提供了良好的基础,预测和评价极震区因岩体动力破坏造成的工程震害和地质灾害,减轻和预防未来地震时的灾害损失,是极震区岩体地震动力破坏研究的目标和方向。 相似文献
18.
2015尼泊尔大地震及喜马拉雅造山带未来地震趋势 总被引：1，自引：1，他引：0
2015年4月25日尼泊尔Ms 8.1级大地震是发生在喜马拉雅造山带中段的低角度逆冲断层运动, 特点是震源很浅, 震中烈度达Ⅺ度, 震害严重。破裂带走向北西西—南东东, 穿越尼泊尔首都加德满都, 使首都建筑遭受严重破坏。该震是1934年以来尼泊尔最大地震, 标志着喜马拉雅带自1950年以来半个世纪的平静期已经结束。自2005年进入新活动期, 至2015年尼泊尔大地震发生已达到活动高潮。预计将持续十到几十年。根据历史地震资料分析, 今后可能沿喜马拉雅带走向发生纵向迁移, 将在喜马拉雅带东段发生更大的地震, 从而使地震高潮达到顶峰而结束, 可能对我国西藏东南、不丹和印度边界产生破坏。另外还可能沿着与喜马拉雅带走向垂直方向向北迁移(即横向迁移), 在几年之内即可在西藏、青海引起破坏性地震, 需要相关省市做好监测预报和防灾工作。 相似文献
19.
Ground motion intensity parameters of past and potential earthquakes are required for a range of purposes including earthquake insurance practice. In regions with no or sparse earthquake recordings, most of the available methods generate only peak ground motion parameters. For cases where full ground motion time histories are required, simulations that consider fault rupture processes become necessary. In this study, a major novel use of simulated ground motions is presented in insurance premium calculations which also require ground motion intensity measures that are not always available through observations. For this purpose, potential earthquakes in Bursa are simulated using stochastic finite-fault simulation method with dynamic corner frequency model. To ensure simulations with reliable synthetic ground motions, input parameters are derived from regional data. Regional model parameters are verified by comparisons against the observations as well as ground motion prediction equations. Next, a potential large magnitude event in Bursa is simulated. Distribution of peak ground motion parameters and time histories at selected locations are obtained. From these parameters, the corresponding Modified Mercalli Intensities (MMI) are estimated. Later, these MMIs are used as the main ground motion parameter in damage probability matrices (DPM). Return period of the scenario earthquake is obtained from the previous regional seismic hazard studies. Finally, insurance rates for Bursa region are determined with implementation of two new approaches in the literature. The probability of the scenario event and the expected mean damage ratios (MDR) from the corresponding DPMs are used, and the results are compared to Turkish Catastrophe Insurance Pool (TCIP) rates. Results show that insurance premiums can be effectively computed using simulated ground motions in the absence of real data. 相似文献
20.
Earthquake-induced landslides in Central America 总被引：11，自引：0，他引：11
Central America is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides. Data are presented for earthquake-triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude. We find that the areas affected by landslides are similar to other parts of the world but in certain parts of Central America, the numbers of slides are disproportionate for the size of the earthquakes. We also find that there are important differences between the characteristics of landslides in different parts of the Central American isthmus, soil falls and slides in steep slopes in volcanic soils predominate in Guatemala and El Salvador, whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in Costa Rica and Panama. Methods for assessing landslide hazards, considering both rainfall and earthquakes as triggering mechanisms, developed in Costa Rica appear not to be suitable for direct application in the northern countries of the isthmus, for which modified approaches are required. 相似文献