对地观测技术用于汶川和玉树地震灾害的研究

汶川、玉树大地震造成了重大人员伤亡和财产损失。地震发生后,对地观测技术成为地震灾害监测与灾情评估的重 要手段。本文将从三个方面论述对地观测技术在上述地震灾害评估和研究中所发挥的作用：一是利用高分辨率光学对地观 测技术,建立堰塞湖、道路损毁、崩塌/滑坡/碎屑流等次生地质灾害的遥感分析方法和模型,系统监测汶川地震次生地质 灾害的空间分布、损毁范围、风险程度;二是利用宽幅和干涉两种模式SAR数据,分析玉树地震的区域地质构造和岩性分 布特征,获得玉树地震同震形变场大小及其空间分布信息,证明了多模式SAR在地震灾情协同分析与评价中的有效性和重 要潜力;三是建立了地震灾害三维模拟评估系统,提高了对地震灾害三维模拟的精确性,为地震灾情的精确三维评估提供 了系统平台。     

地震动力学与板块构造:地震灾害评估

作为地震灾害评估的理论基础,地震动力学主要研究与地震活动有关的断裂机制、破裂过程、震源辐射和由此而引起的地震波的传播及地面运动规律。对地震力学、震源辐射和能量释放等经典理论问题进行了系统研究。在此基础上,应用最新的定量地震学研究方法,以逻辑树的形式综合地震、地质和大地测量资料,提供了不同构造环境和断裂机制条件下地震灾害评估的概率分析和确定性分析实例。用于震源分析的典型构造类型包括板内地壳震源层、地壳活动断层及其速率、板块俯冲界面和俯冲板片。由于输入模型中不确定因素的存在,如输入参数的随机性和科学分析方法本身的不确定性,对分析结果的不确定性需审慎对待。通常对不同的模型或参量,包括地面衰减模型,进行加权平均可较为合理地减小结果的偏差：概率分析和确定性分析方法的结合亦为可取之有效途径。     

两种数值模式资料的平均海平面气压和地面风速在中国区域的评估

利用中国气象局国家级自动站(2 421个)的观测资料, 分别对2012年的ECMWF(欧洲中期数值预报中心)和JMA(日本气象厅)数值模式资料的平均海平面气压和地面风速在中国地区的适用性进行了对比研究.结果表明:两种数值模式资料均能在一定程度上反映观测资料所具有的时空分布特征, 东部地区的适用性均要高于西部地区. 对于平均海平面气压, 在西南地区JMA比ECMWF资料更接近实际观测; 而在其他地区, 两种数值模式资料都较接近实际观测, 冬季的结果比夏季好. 对于地面风速, 这两种数值模式资料各具优势.在中国东南部地区, JMA相对于ECMWF的地面风速资料更接近实际观测值, 而在中国西部地区, 则相反.就8个时次的年变化而言, ECMWF资料的年变化趋势与观测资料更为一致, 而JMA资料的地面风速大小与观测资料更为接近.     

黄河三花区间天气雷达测雨技术应用研究

采用改进窗概率配对方法以及自适应卡尔曼滤波和变分联合的方法分别对郑州和三门峡两部新一代多普勒天气雷达观测资料以及地面自动雨量站资料进行了降水反演和评估,并实现了两部雷达降水反演的拼图.评估结果表明在雷达测雨中,利用改进窗概率配对方法确定的Z-R关系反演的雷达测雨精度要优于目前国内业务雷达采用的经验关系式,而且经过自适应卡尔曼滤波和变分联合处理之后,既保持了雷达观测降水的空间分布特征,也显著提高了雷达测雨的精度.     

上海地区地震动参数衰减关系的建立及其在地震烈度预测中的应用

在缺乏强震地面运动观测资料的上海地区用烈度资料建立该区的地震烈度和峰值加速度衰减关系，采用一种新方法——比例系数法计算其标准偏差，并通过实例验证这一关系。最后对该区未来百年内可能遭遇的最大地震烈度进行预测     

上海地区地震动参数衰减关系的建立及其在地震烈度预测中…

在缺乏强震地面运动观测资料的上海地区用烈度资料建立该区的地震烈度和峰值加速度衰减关系，采用一种新方法－比例系数法计算其标准偏差，并通过实例验证这一关系。最后对该区未来百年内可能遭遇的最大地震烈度进行预测。     

长春市地质灾害的探讨

本文根据长春市新构造特征,尤其是活动断裂带的强烈活动性和比较复杂的地震地质背景资料重点探讨本区可能发生的地震灾害,新立城水库溃坝引起的洪水灾害及地面塌陷灾害,圈定地震灾害的烈度区划、洪水灾害和地面塌陷灾害的范围,在此基础上进一步提出尽可能避免或减轻地质灾害的有力措施。这对于长春市城市规划、国民经济建设、工程地质等方面,有着重要的理论和实际意义。     

基于空间信息技术的地震灾害监测评估

空间信息技术即包括地理信息系统GIS、遥感RS、全球导航卫星系统GNSS以及数字地球在内的地球空间信息科学。随着计算机和空间对地观测技术的发展,空间信息技术已逐渐应用于防震减灾领域。本文通过实际震例分别对目前基于GIS、RS技术的地震灾害监测评估方法进行了分析研究,总结了其优越性以及存在的问题,并结合数字地球平台可视化展示了综合多源数据空间信息技术方法进行的震害评估效果。     

“上海市防震减灾应急决策信息系统”的建立

为适应上海经济建设高速发展和超大城市防震减灾工作的需要,已将ＧＩＳ技术应用于“上海市防震减灾应争决策信息系统（宝山试点区）”,此系统由七个功能模块组成,即：地震地质基本信息、地震灾害快速评估子系统、地震应急决策信息子系统、信息查询、系统维护管理、帮助、退出等,其核心部分地地震灾害快速评估子系统和地震应急决策信息子系统。还介绍了航片遥感技术在ＧＩＳ中的应用。     

赣江流域TRMM遥感降水对地面站点观测的可替代性

多卫星遥感降水产品为无/缺资料地区的水文过程模拟提供了新的数据来源。结合地面高密度雨量站网,在中国典型暴雨区赣江流域定量评估两种TRMM降水产品(3B42V7和3B42RTV7)的精度,并通过耦合分布式水文模型CREST,探讨了水文模拟中TRMM卫星降水产品对地面观测降水的可替代性。研究表明:3B42和3B42RT与地面观测流域平均月降水相关系数达到0.9以上,偏差在5%以内,日尺度上相关性略差,偏差略有增加。同时设计2种水文模拟对比试验:情景I为静态参数,使用地面雨量站降水率定模型参数,采用卫星降雨验证模型;情景II为动态参数,采用卫星数据重新率定模型参数,再利用卫星降雨验证模型。对比结果表明:情景II中完全使用TRMM降水后模型效果明显改善,证明TRMM卫星数据在赣江流域具有替代地面站点观测的潜力,但需要重新根据卫星降雨率定模型。     

A technical note on seismic microzonation in the central United States

Microzonation is an effort to evaluate and map potential hazards found in an area, urban area in particular, that could be induced by strong ground shaking during an earthquake. These hazards include: ground motion amplification, liquefaction, and slope failure. The microzonation maps, depicting ground-motion amplification, liquefaction, and landslide potentials, can be produced if the ground motion on bedrock (input) and the site conditions are known. These maps, in combination with ground-motion hazard maps (on bedrock), can be used to develop a variety of hazard mitigation strategies such as seismic risk assessment, emergency response and preparedness, and land-use planning. However, these maps have certain limitations that result from the nature of regional mapping, data limitations, generalization, and computer modeling. These microzonations show that when strong ground shaking occurs, damage is more likely to occur, or be more severe, in the higher hazard areas. The zones shown on the hazard maps should not serve as a substitute for site-specific evaluations.     

Seismic Hazard Assessment in the Tihamat Asir Region, Southwestern Saudi Arabia

The occurrence of earthquakes, faulting of Pleistocene sediments, uplifting of Pleistocene coral reefs, recent incised wadis and lava effusions in addition to hot springs all clearly indicate that southeastern Saudi Arabia is tectonically active. This paper reviews the tectonic features of southwestern Saudi Arabia and provides new approaches and maps for the interpretation of old and recent earthquake data for improved assessment of the regional tectonics. A regionalized variable approach is used to develop earthquake groundmotion hazard maps for the region, based on geostatistical methods using the kriging technique. This hazard must be considered in any design/construction of engineering structures in the region. The application of kriging for estimating the ground shaking in the study region succeeded clearly in accomplishing its ultimate aim where the generated groundmotions are well correlated with the instrumental magnitude and historical intensity of any earthquake occurrence in the study region.     

A new model for the prediction of earthquake ground-motion duration in Iran

The paper proposes a new empirical model to estimate earthquake ground-motion duration, which significantly influences the damage potential of an earthquake. The paper is concerned with significant duration parameters that are defined as the time intervals between which specified values of Arias intensity are reached. In the proposed model, significant duration parameters have been expressed as a function of moment magnitude, closest site-source distance, and site condition. The predictive model has been developed based on a database of earthquake ground-motion records in Iran, containing 286 records up to the year 2007, and a random-effect regression procedure. The result of the proposed model has been compared with that of other published models. It has been found that the proposed model can predict earthquake ground-motion duration in Iran with adequate accuracy.     

Earthquake losses due to ground failure

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.     

Rapid estimation of ground-shaking maps for seismic emergency management in the Campania Region of southern Italy

Strong ground-shaking mapping soon after a moderate-to-large earthquake is crucial to recognize the areas that have suffered the largest damage and losses. These maps have a fundamental role for emergency services, loss estimation and planning of emergency actions by the Civil Protection Authorities. This is particularly important for areas with high seismic risk levels, such as the Campania-Lucania Region in southern Italy. Taking advantage of the Irpinia Seismic Network (ISNet), a recently installed dense and wide dynamic seismic network, we have developed a procedure for rapid estimation of ground-shaking maps after moderate-to-large earthquakes (GRSmap). This uses an optimal data gridding scheme designed to account for bi-dimensional features of strong ground-motion fields, such as directivity, radiation patterns and focal mechanisms, to which most damage can be correlated. The basis of the mapping technique is a triangulation procedure to locally correct predicted data at the triangle barycentres where their vertices correspond to seismic stations. The method has been tested off-line using a simulated M 6.6 earthquake located at the centre of ISNet and applied to data of the 23 November 1980 Irpina M 6.9 earthquake recorded by a sparse network. This has highlighted its ability to predict peak ground-motion parameters of large magnitude earthquakes with respect to the attenuation relationships.     

Hazus-MH earthquake modeling in the central USA

This investigation was undertaken to assess the sensitivity of the Hazus-MH (v2.0) earthquake model to model parameters and to guide the selection of these parameters for realistic earthquake-loss assessment in the central USA. To accomplish these goals, we performed several sensitivity analyses and a validation assessment using earthquake damage surveys from the 2008 M5.2 Mt. Carmel, Illinois earthquake. We evaluated the sensitivity of the Hazus-MH earthquake model to the selection of seismic hazard data, attenuation function, soils data, liquefaction data, and structural fragility curves. These sensitivity analyses revealed that earthquake damage, loss, and casualty estimates are most sensitive to the seismic hazard data and selection of the attenuation function. The selection of the seismic hazard data and attenuation function varied earthquake damages and capital-stock losses by ±68?% and casualty estimates by ±84?%. The validation assessment revealed that Hazus-MH overpredicted observed damages by 68?C221?% depending on the model parameters employed. The model run using region-specific soils, liquefaction, and structure fragility curves produced the most realistic damage estimate (within 68?% of actual damages). Damage estimates using default Hazus-MH parameters were overpredicted by 155?%. The uncertainties identified here are similar to uncertainties recognized in other Hazus-MH validation assessments. Despite uncertainties in Hazus-MH earthquake-loss estimates, such estimates are still useful for planning and response so long as the limitations of the results are properly conveyed to planners, decision makers, emergency responders, and the public.     

Global Seismic Hazard Assessment Based on Area Source Model and Seismicity Data

A global seismic hazard assessment was conducted using the probabilistic approach in conjunction with a modified means of evaluating the seismicity parameters. The earthquake occurrence rate function was formulated for area source cells from recent instrumental earthquake catalogs. For the statistical application of the G–R relation of each source cell, the upper- and lower-bound magnitudes were determined from, respectively, historical earthquake data using a Kernel smoothing operator and detection thresholds of recent catalogs. The seismic hazard at a particular site was obtained by integrating the hazard contribution from influencing cells, and the results were combined with the Poisson distribution to obtain the seismic hazard in terms of the intensity at 10% probability of exceedance for the next 50 years. The seismic hazard maps for three countries, constructed using the same method, agree well with the existing maps obtained by different methods. The method is applicable to both oceanic and continental regions, and for any specific duration of time. It can be used for those regions without detailed geological information or where the relation between existing faults and earthquake occurrence is not clear.     

A media-based assessment of damage and ground motions from the january 26th, 2001<Emphasis Type="Italic">M</Emphasis> 7.6 Bhuj,India earthquake

We compiled available news and internet accounts of damage and other effects from the 26th January, 2001, Bhuj earthquake, and interpreted them to obtain modified Mercalli intensities at over 200 locations throughout the Indian subcontinent. These values are used to map the intensity distribution using a simple mathematical interpolation method. The maps reveal several interesting features. Within the Kachchh region, the most heavily damaged villages are concentrated towards the western edge of the inferred fault, consistent with western directivity. Significant sedimentinduced amplification is also suggested at a number of locations around the Gulf of Kachchh to the south of the epicenter. Away from the Kachchh region intensities were clearly amplified significantly in areas that are along rivers, within deltas, or on coastal alluvium such as mud flats and salt pans. In addition we use fault rupture parameters inferred from teleseismic data to predict shaking intensity at distances of 0–1000 km. We then convert the predicted hard rock ground motion parameters to MMI using a relationship (derived from internet-based intensity surveys) that assigns MMI based on the average effects in a region. The predicted MMIs are typically lower by 1–2 units than those estimated from news accounts. This discrepancy is generally consistent with the expected effect of sediment response, but it could also reflect other factors such as a tendency for media accounts to focus on the most dramatic damage, rather than the average effects. Our modeling results also suggest, however, that the Bhuj earthquake generated more high-frequency shaking than is expected for earthquakes of similar magnitude in California, and may therefore have been especially damaging.