Modelling liquefaction-induced building damage in earthquake loss estimation

The assessment of building damage caused by liquefaction-induced ground deformations requires the definition of building capacity and vulnerability as a function of the demand, as well as damage scales to describe the state of the damaged building. This paper presents a framework for resolving these issues within the context of earthquake loss estimations, where large variations in building stock and ground conditions must be considered. The principal modes of building response to both uniform and differential ground movements are discussed and the uncertainties in their evaluation are highlighted. A unified damage scale is proposed for use in both reconnaissance and assessment of all modes of building damage, including ‘rigid body’ response of structures on stiff foundations to uniform or differential ground movements. The interaction of ground shaking and liquefaction in the context of induced structural damage is also briefly considered. The paper raises important aspects of earthquake loss estimations in regions of liquefaction potential, which remain relatively poorly defined at present.     

Rapid estimation of earthquake loss based on instrumental seismic intensity: design and realization

As a result of our ability to acquire large volumes of real-time earthquake observation data, coupled with increased computer performance, near real-time seismic instrument intensity can be obtained by using ground motion data observed by instruments and by using the appropriate spatial interpolation methods. By combining vulnerability study results from earthquake disaster research with earthquake disaster assessment models, we can estimate the losses caused by devastating earthquakes, in an attempt to provide more reliable information for earthquake emergency response and decision support. This paper analyzes the latest progress on the methods of rapid earthquake loss estimation at home and abroad. A new method involving seismic instrument intensity rapid reporting to estimate earthquake loss is proposed and the relevant software is developed. Finally, a case study using the M _L4.9 earthquake that occurred in Shun-chang county, Fujian Province on March 13, 2007 is given as an example of the proposed method.     

Behavior of large fill dams during earthquake and earthquake damage

This paper describes the behavior of and damage to large fill dams during earthquakes. Although fill dams have been constructed since olden times, there are only records of recent earthquake damage. We analyzed the behavior of fill dams of at least 15 m in height during earthquakes, and investigated the damage to the fill dams. The fact that fill dams that are designed and constructed based on the modern design standards have never been failed but have been only slightly affected by past earthquakes in Japan and other nations suggests that such large fill dams are highly earthquake resistant. The modern conventional design methods (soil engineering control of the bank soil, method for evaluating slip safety, and evaluation method of the foundation ground) are thus fully adequate for determining earthquake resistance.     

基于遥感和GIS的建筑物震害损失评估方法研究与实现

介绍了一种使用遥感技术进行震后损失快速评估的方法,评估流程包括震害提取和损失评估两个部分。评估方式根据需求可以分为基于震害指数的评估和基于图像分类结果的评估两种模式,前者通过震害指数与烈度的关系得到地面居民住地的宏观震害情况,结合地震应急数据进行建筑物损失评估;后者采用图像处理技术,选取典型震害样本以图像分类技术得到地面居民住地的分级分类的震害结果,然后计算参数进行损失评估。损失评估的计算根据震害提取模式而不同。这种遥感震害评估方法和计算流程结合了遥感和GIS技术,以满足实际工作需求目标,提高了震害提取的自动化程度,实现多人工作模式,通过有效率的人机交互来提高遥感震害评估的速度。     

An earthquake scenario for the microzonation of Sofia and the vulnerability of structures designed by use of the Eurocodes

The study of the site effects and the microzonation of a part of the metropolitan Sofia, based on the modelling of seismic ground motion along three cross-sections are performed. Realistic synthetic strong motion waveforms are computed for scenario earthquakes (M=7) applying a hybrid modelling method, based on the modal summation technique and finite differences scheme. The synthesized ground motion time histories are source and site specific. The site amplification is determined in terms of response spectra ratio (RSR). A suite of time histories and quantities of earthquake engineering interest are provided. The results of this study constitute a “database” that describes the ground shaking of the urban area. A case study of experiment-based assessment of vulnerability of a cast-in-situ single storey, industrial, reinforced concrete frame, designed according to Eurocodes 2 and 8 is presented. The main characteristics of damage index and storey drift are discussed for the purposes of microzonation.     

Combining USGS ShakeMaps and the OpenQuake-engine for damage and loss assessment

The evaluation of the potential impact of strong seismic events shortly after their occurrence is a critical step to organise emergency response and consequently minimise the adverse effects of earthquakes. The estimation of the impact from earthquakes considering the observed ground shaking from past events can be useful for the calibration of existing exposure and/or fragility and vulnerability models. This study describes a methodology to combine the publicly available information from the USGS ShakeMap system and the open-source software OpenQuake engine for the assessment of damage and losses. This approach is employed to estimate the number of structural collapses considering the 2012 Magnitude 5.9 Emilia-Romagna (Italy) earthquake and the aggregated economic loss because of the 2010 Magnitude 7.1 Darfield (New Zealand) event. Several techniques to calculate the ground shaking in the affected region considering the spatial and interperiod correlations in the intra-event ground motion residuals are investigated and their influence in the resulting damage or loss estimates are evaluated.     

公路桥梁地震易损性和震后恢复过程

采用专家调查的方式,统计的我国各种主要公路桥梁在不同烈度的地震发生后可能遭受的结构破坏和功能损失,以及地震发生后所需要的恢复时间。通过分析,给出了大、中、小种规模的斜拉、悬索、板梁式和拱式桥梁的结构破坏概率矩阵、设施损失率、功能损失率分布、损失功能恢复所需要的时间和桥梁在遭受破坏期间所损失的工作日数,并将研究结果与唐山地震之后的实际调查结果进行了对比,得到了一些有益的结果。     

Verifying adequacy of the seismic deformation method by using real examples of earthquake damage

In a seismic design, the dynamic loads are generally dependent on the inertial interaction caused by earthquake. But for the foundations embedded in soil, the dynamic loads are influenced by both the inertial and kinematic interactions among superstructure, foundation and soil. Especially, when a foundation is embedded in soft surface ground, the effects due to the kinematic interaction increase and should be considered in seismic design. For this reason, a method called seismic deformation method (SDM), which is suitable for an intensive earthquake motion (level 2 earthquake motion), has been stipulated recently in a new design code called Seismic Design Code for railway structures (the Railway Code, drawn up by Railway Technical Research Institute, Japan, 1999) [Railway Technical Research Institute. Seismic Design Code for railway structures. Tokyo: Maruzen; 1999]. In order to grasp the suitability of the SDM to actual structures, pile foundations, which experienced the Hyogoken-Nanbu earthquake, were taken as the objects for investigations. Comparison studies between the SDM analysis and reconnaissance were conducted. As a result, the adequacy of the SDM to actual foundations was confirmed to prove good agreement between the two results from the viewpoint of engineering practice.In addition, determination of indices for seismic-performance evaluation and speculation of damage mechanism of the foundations are also discussed in this paper.     

Determination and integration of appropriate spatial scales for river basin modelling

Appropriate spatial scales of dominant variables are determined and integrated into an appropriate model scale. This is done in the context of the impact of climate change on flooding in the River Meuse in Western Europe. The objective is achieved by using observed elevation, soil type, land use type and daily precipitation data from several sources and employing different relationships between scales, variable statistics and outputs. The appropriate spatial scale of a key variable is assumed to be equal to a fraction of the spatial correlation length of that variable. This fraction was determined on the basis of relationships between statistics and scale and an accepted error in the estimation of the statistic of 10%. This procedure resulted in an appropriate spatial scale for precipitation of about 20 km in an earlier study. The application to river basin variables revealed appropriate spatial scales for elevation, soil and land use of respectively 0·1, 5·3 and 3·3 km. The appropriate model scale is determined by multiplying the appropriate variable scales with their associated weights. The weights are based on SCS curve number method relationships between the peak discharge and some specific parameters like slope and curve number. The values of these parameters are dependent on the scale of each key variable. The resulting appropriate model scale is about 10 km, implying 225–250 model cells in an appropriate model of the Meuse basin meant to assess the impact of climate change on river flooding. The usefulness of the appropriateness procedure is in its ability to assess the appropriate scales of the individual key variables before model construction and integrate them in a balanced way into an appropriate model scale. Another use of the procedure is that it provides a framework for decisions about the reduction or expansion of data networks and needs. Copyright © 2003 John Wiley & Sons, Ltd.     

A GIS-based seismic hazard,building vulnerability and human loss assessment for the earthquake scenario in Tabriz

A GIS-oriented procedure that may partially illuminate the consequences of a possible earthquake is presented in two main steps (seismic microzonation and vulnerability steps) along with its application in Tabriz (a city in NW Iran). First, the detailed geological, geodetical, geotechnical and geophysical parameters of the region are combined using an Analytic Hierarchy Process (AHP) and a deterministic near-field earthquake of magnitude 7 in the North Tabriz Fault is simulated. This simulation provides differing intensities of ground shaking in the different districts of Tabriz. Second, the vulnerability of buildings, human losses and basic resources for survivors is estimated in district two of the city based on damage functions and relational analyses. The results demonstrate that 69.5% of existing buildings are completely destroyed, and the rate of fatalities is approximately 33% after a nighttime scenario. Finally, the same procedure was applied to an actual earthquake (first event on the 11th of August, 2012 of the Ahar twin earthquakes) to validate the presented model based on two aspects: (1) building damages and (2) seismic intensity.     

Development of an earthquake loss model for Turkish catastrophe insurance

Following the devastating Kocaeli and Düzce earthquakes of August andNovember 1999, the Turkish Government was faced with an enormousfinancial burden as a result of its statutory obligation to cover the full costsof rebuilding. In order to offset this liability in the future – which has hadan adverse effect on the Government's economic programme – acompulsory earthquake insurance scheme has been introduced for allhouseholders in Turkey. A key element for successful implementation ofthis novel and ambitious programme is the transfer of the earthquake riskabsorbed by the Turkish Catastrophe Insurance Pool (TCIP) to theinternational reinsurance market. An earthquake loss model, described inthis paper, has been developed for the TCIP to serve as a basis for thedecision-making process with respect to the pricing of its insurance policy,risk control, the purchase of reinsurance, and the transfer of seismic risk.Sample results of the loss calculations are presented.     

Evidence for fault-related directionality and localized site effects from strong motion recordings of the 2003 Boumerdes (Algeria) earthquake: Consequences on damage distribution and the Algerian seismic code

The Algiers–Boumerdes region has been struck by a destructive magnitude 6.8 (M_w) earthquake on May 21, 2003. The study presented in this paper is based on main shock strong motions from 13 stations of the Algerian accelerograph network. A maximum 0.58g peak ground acceleration (PGA) has been recorded at 20 km from the epicenter, only about 150 m away from a PGA of 0.34g, with both a central frequency around 5 Hz, explained by a strong very localized site effect, confirmed by receiver function technique results showing peaks at 5 Hz with amplitudes changing by a factor of 2. Soil amplifications are also evidenced at stations located in the quaternary Mitidja basin, explaining the higher PGA values recorded at these stations than at stations located on firm soil at similar distances from the epicenter. A fault-related directionality effect observed on the strong motion records and confirmed by the study of the seismic movement anisotropy, in agreement with the N65 fault plan direction, explains the SW–NE orientation of the main damage zone. In the near field, strong motions present a high-frequency content starting at 3 Hz with a central frequency around 8 Hz, while in the far field their central frequency is around 3 Hz, explaining the high level of damage in the 3- to 4-story buildings in the epicentral zone. The design spectra overestimate the recorded mean response spectra, and its high corner frequency is less than the recorded one, leading to a re-examination of the seismic design code that should definitively integrate site-related coefficient, to account for the up to now neglected site amplification, as well as a re-modeling of the actual design spectra. Finally, both the proposed Algerian attenuation law and the worldwide laws usually used in Algeria underestimate the recorded accelerations of the 6.8 (M_w) Boumerdes earthquake, clearly showing that it is not possible to extrapolate the proposed Algerian law to major earthquakes.     

Detailed assessment of structural characteristics of Turkish RC building stock for loss assessment models

Assessment of the seismic vulnerability of the building stock in the earthquake-prone Marmara region of Turkey is of growing importance since such information is needed for reliable estimation of the losses that possible future earthquakes are likely to induce. The outcome of such loss assessment exercises can be used in planning of urban/regional-scale earthquake protection strategies; this is a priority in Turkey, particularly following the destructive earthquakes of 1999. Considering the size of the building inventory, Istanbul and its surrounding area is a case for which it is not easy to determine the structural properties and characteristics of the building stock. In this paper, geometrical, functional and material properties of the building stock in the northern Marmara Region, particularly around Istanbul, have been investigated and evaluated for use in loss estimation models and other types of statistic- or probability-based studies. In order to do that, the existing reinforced concrete (RC) stock has been classified as ‘compliant’ or ‘non-compliant’ buildings, dual (frame-wall) or frame structures and emergent or embedded-beam systems. In addition to the statistical parameters such as mean values, standard deviations, etc., probability density functions and their goodness-of-fit have also been investigated for all types of parameters. Functionalities such as purpose of use and floor area properties have been defined. Concrete properties of existing and recently constructed buildings and also characteristics of 220 and 420 MPa types of steel have been documented. Finally, the financial effects of retrofitting operations and damage repair have been investigated.     

基于高分辨率遥感的建筑群在地震灾害中的脆弱性和风险分析方法及其应用

近年来高分辨率遥感技术快速发展,其在灾害研究领域的应用也越来越广。将遥感技术用于建筑群在地震灾害中的脆弱性和损失风险分析,不仅能保证建筑物类型和数量调查更新的时效性,而且有利于进行不同时期损失风险的对比分析,以便揭示震灾损失风险的变化规律。通过分析高分辨率建筑群的遥感影像特征,设计了一套提取建筑物属性信息(高度和面积)的方法,并通过实地调查验证了其可行性;将提取的建筑群属性信息与传统的震灾风险分析模型相结合,即可实现对研究区建筑群在地震灾害中的脆弱性和损失风险分析。以唐山市区和9个乡镇2009年的建筑物为研究对象,提取了它们的属性信息,在设定地震烈度情景下,分析了这些建筑物在地震灾害中的脆弱性和损失风险。     

地震损失的空间相关性及其对震害损失估计的影响

在地震危险性分析或者地震损失分布评估中,需要考虑地震损失的空间相关性的影响。目前对地震损失空间相关性的研究,主要是基于经验或半经验的方法,没有经过实际地震损失分布的验证。本文基于2011年东日本大地震收集到的55万条建筑物破坏的详细数据得出了基于实际震害的地震损失随距离关系变化的空间相关性衰减规律,给出了一个基于实际数据的拟合公式,并将其应用于最新开发的基于高精度模拟的巨灾风险分析中。利用北京地区多个地震为算例,研究了实现空间相关性模拟的样本精度问题,并且给出了不同空间相关系数对地震损失分布的影响,从而能为未来的防震减灾工作提供更好的地震损失估计结果。     

Seismic hazard and risk in Shanghai and estimation of expected building damage

The People's Republic of China is in the process of rapid demographic, economic and urban change including nationwide engineering and building construction at an unprecedented scale. The mega-city of Shanghai is at the centre of China's modernisation. Rapid urbanisation and building growth have increased the exposure of people and property to natural disasters. The seismic hazard of Shanghai and its vicinity is presented from a seismogenic free-zone methodology. A PGA value of 49 cm s⁻² and a maximum intensity value of VII for the Chinese Seismic Intensity Scale (a scale similar to the Modified Mercalli) for a 99% probability of non-exceedance in 50 years are determined for Shanghai city. The potential building damage for three independent districts of the city centre named Putuo, Nanjing Road and Pudong are calculated using damage vulnerability matrices. It is found that old civil houses of brick and timber are the most vulnerable buildings with potentially a mean probability value of 7.4% of this building structure type exhibiting the highest damage grade at intensity VII.     

Real-time prediction of earthquake potential damage: A case study for the January 8, 2022 MS 6.9 Menyuan earthquake in Qinghai,China

It is critical to determine whether a site has potential damage in real-time after an earthquake occurs, which is a challenge in earthquake disaster reduction. Here, we propose a real-time Earthquake Potential Damage predictor (EPDor) based on predicting peak ground velocities (PGVs) of sites. The EPDor is composed of three parts: (1) predicting the magnitude of an earthquake and PGVs of triggered stations based on the machine learning prediction models; (2) predicting the PGVs at distant sites based on the empirical ground motion prediction equation; (3) generating the PGV map through predicting the PGV of each grid point based on an interpolation process of weighted average based on the predicted values in (1) and (2). We apply the EPDor to the 2022 M_S 6.9 Menyuan earthquake in Qinghai Province, China to predict its potential damage. Within the initial few seconds after the first station is triggered, the EPDor can determine directly whether there is potential damage for some sites to a certain degree. Hence, we infer that the EPDor has potential application for future earthquakes. Meanwhile, it also has potential in Chinese earthquake early warning system.     

The study of barrier fracture in relation to earthquake and rockburst prediction

One of the simplest models of earthquakes and rockbursts was studied in laboratory conditions in which the fracture was initiated in a barrier between two preexisting faults. The treated models were built of concrete; during the construction of the models, the stress concentrators were inserted inside the models. This arrangement enabled the shear displacement to occur during uniaxial loading of the model. The tests were made on the series of models, the sizes of which were mutually varying more than one order. In the process of the barrier fracture propagation, the following were investigated: the time and space changes of local deformations as well as the acoustic emission, velocities and amplitudes of elastic waves, electrical conductivity and proper electro-induction. The process of barrier fracturing can be understood in three fundamental stages. In the course of the first stage, the density of small tensile cracks increases considerably, while the volume in which they exist is gradually enlarged. In the second stage, as the result, of these cracks coupling, longer shear cracks are created. During the coupling, due to the development of numerous regions of unstable deformation, the zones of nonequal rigidity arise in the treated medium, distributed within it in a mosaic-like pattern. In the third stage, the main fracture is prepared and formed with simultaneous unloading of the surrounding medium. The process of crack forming is gradually localized into a more narrow zone.The second and third stages of fracture forming are reflected in variations of all the above-mentioned physical parameters which are therefore identified as the precursors of the main fracture. By means of the series of precursors it is possible to find the reliable prediction of a barrier fracture.     

The use of modern statistical theories in the assessment of earthquake hazard, with application to quiet regions of eastern North America

It is generally accepted that both deterministic and statistical approaches are useful for the characterization of earthquake hazard. Although the most reliable estimates of seismic hazard can only be based on an improved understanding of the earthquake mechanism, efficient utilization of the appropriate methods provided by recent statistical theories is also important in seismic risk analysis. This is especially true in regions where the connection between seismicity and geologic structure is tenuous at best. We are particularly interested in developing better statistical treatments of data for regions with little known seismic activity. To this end, we have applied three statistical methods to the historical record of seismicity in relatively quiet regions of eastern North America. These are: (1) the threshold method for tail inference, a new theory for modeling earthquakes with sizes above a given threshold, (2) the ‘bootstrap’ technique in which the characteristics of an unknown population are simulated by replacing the true population by an estimated one, and (3) a technique to estimate the number of earthquakes below a given size, in order to compensate for the under-reporting of small earthquakes in most catalogs. A combination of these techniques has been used to estimate the probabilities of future large earthquakes for the regions studied. Because of limitations imposed by existing catalogs, the size estimate used has been maximum intensity.     

川滇地震科学实验场地震目录最小完整性震级分析

地震目录是地震监测预报、地震活动性等研究的重要资料.川滇地震科学实验场地区近几十年来积累了大量的地震记录,为实验场的地震科学研究提供了宝贵的数据.地震台网密度和仪器观测精度是逐步提高的,不同时期地震目录的完整性存在差异,因此进行现代仪器观测记录的地震目录最小完整性震级（M_C,Magnitude of Completeness）分析,对正确研究和认识该地区地震活动规律及其影响因素等具有重要意义.本文采用震级—序号方法、最大曲率法（MAXC,Maximum Curvature）和拟合度检测法（GFT,Goodness-of-Fit Test）分析了川滇地震科学实验场地区1970—2018年地震目录的最小完整性震级M_C值,得到了实验场地区及其内部各地震区（带）M_C值的时间演化特征和空间分布特征.结果表明,实验场地区及其内部各地震区（带）M_C值变化趋势大致为1970—1986年M_L2.0~2.6,1987—1999年M_L2.5~2.6,2000—2008年后M_L1.4~2.1,2009—2018年M_L1.2~1.9;实验场地区M_C值的空间分布大致呈现东北部和西南部较低、西北部和东南部较高的特征,其中云南最南端的澜沧—耿马区和思普区、四川西北部的理塘—木里区以及川藏交界处的金沙江带M_C值普遍较高,云南北部和四川南部的松潘—龙门山带、安宁河带、元谋区、楚雄—建水带和大理—丽江—盐源区M_C值普遍较低;强震会使M_C值出现突然升高、之后逐渐恢复的现象,其中M_C值升高程度与震级有一定相关性,并且强震导致的M_C值升高是M_C值空间和时间分布不均匀的原因之一.