Showing papers in "Earthquake Spectra in 2007"

Structure-specific scalar intensity measures for near source and ordinary earthquake ground motions

Abstract: Introduced in this paper are several alternative ground-motion intensity measures (IMs) that are intended for use in assessing the seismic performance of a structure at a site susceptible to near-source and/or ordinary ground motions. A comparison of such IMs is facilitated by defining the “efficiency” and “sufficiency” of an IM, both of which are criteria necessary for ensuring the accuracy of the structural performance assessment. The efficiency and sufficiency of each alternative IM, which are quantified via (i) nonlinear dynamic analyses of the structure under a suite of earthquake records and (ii) linear regression analysis, are demonstrated for the drift response of three different moderate- to long-period buildings subjected to suites of ordinary and of near-source earthquake records. One of the alternative IMs in particular is found to be relatively efficient and sufficient for the range of buildings considered and for both the near-source and ordinary ground motions.

Creating Fragility Functions for Performance-Based Earthquake Engineering:

Abstract: The Applied Technology Council is adapting PEER's performance-based earthquake engineering methodology to professional practice. The methodology's damage-analysis stage uses fragility functions to calculate the probability of damage to facility components given the force, deformation, or other engineering demand parameter (EDP) to which each is subjected. This paper introduces a set of procedures for creating fragility functions from various kinds of data: (A) actual EDP at which each specimen failed; (B) bounding EDP, in which some specimens failed and one knows the EDP to which each specimen was subjected; (C) capable EDP, where specimen EDPs are known but no specimens failed; (D) derived, where fragility functions are produced analytically; (E) expert opinion; and (U) updating, in which one improves an existing fragility function using new observations. Methods C, E, and U are all introduced here for the first time. A companion document offers additional procedures and more examples.

Exploring the Concept of Seismic Resilience for Acute Care Facilities

Abstract: This paper explores the operational and physical resilience of acute care facilities, recognizing that the key dimension of acute care facilities is not a simple engineering unit. Quantification of resilience is first approached from the broader societal context, from which the engineering subproblem is formulated, recognizing that, to operate, hospitals depend intricately on the performance of their physical infrastructure from the integrity of structural systems and nonstructural systems, lifelines, components, and equipment. Quantification relates the probability of exceeding floor accelerations and interstory drifts within a specified limit space, for the structural and nonstructural performance. Linear and nonlinear structural responses are considered, as well as the impact of retrofit or repair. Impact on time to recovery is considered in all cases. The proposed framework makes it possible to relate probability functions, fragilities, and resilience in a single integrated approach, and to further develop general tools to quantify resilience for sociopolitical-engineering decisions. DOI: 10.1193/1.2431396

Analytical Seismic Fragility Curves for Typical Bridges in the Central and Southeastern United States

Abstract: Seismic fragility curves for classes of highway bridges are essential for risk assessment of highway transportation networks exposed to seismic hazards. This study develops seismic fragility curves for nine classes of bridges (common three-span, zero-skew bridges with non-integral abutments) common to the central and southeastern United States. The methodology adopted uses 3-D analytical models and nonlinear time-history analyses. An important aspect of the selected methodology is that it considers the contribution of multiple bridge components. The results show that multispan steel girder bridges are the most vulnerable of the considered bridge classes while single-span bridges tend to be the least vulnerable. A comparison of the proposed fragility curves with those currently found in HAZUS-MH shows a strong agreement for the multispan simply supported steel girder bridge class. However, for other simply supported bridge classes (concrete girder, slab), the proposed fragility curves suggest a lower vulnerability level than presented in HAZUS-MH. DOI: 10.1193/1.2756815

A Seismic Design Lateral Force Distribution Based on Inelastic State of Structures

Abstract: It is well recognized that structures designed by current codes undergo large inelastic deformations during major earthquakes. However, lateral force distributions given in the seismic design codes are typically based on results of elastic-response studies. In this paper, lateral force distributions used in the current seismic codes are reviewed and the results obtained from nonlinear dynamic analyses of a number of example structures are presented and discussed. It is concluded that code lateral force distributions do not represent the maximum force distributions that may be induced during nonlinear response, which may lead to inaccurate predictions of deformation and force demands, causing structures to behave in a rather unpredictable and undesirable manner.A new lateral force distribution based on study of inelastic behavior is developed by using relative distribution of maximum story shears of the example structures subjected to a wide variety of earthquake ground motions. The results show that the suggested lateral force distribution, especially for the types of framed structures investigated in this study, is more rational and gives a much better prediction of inelastic seismic demands at global as well as at element levels. DOI: 10.1193/1.2753549

Update to ASCE/SEI 41 Concrete Provisions

Abstract: A proposed supplement to ASCE/SEI 41 Seismic Rehabilitation of Existing Buildings has been developed for the purpose of updating provisions related to existing reinforced concrete buildings. Based on experimental evidence and empirical models, the proposed supplement includes revisions to modeling parameters and acceptance criteria for reinforced concrete beams, columns, structural walls, beam-column joints, and slab-column frames. The revisions are expected to result in substantially more accurate and, in most cases, more liberal assessments of the structural capacity of concrete components in seismic retrofit projects. DOI: 10.1193/1.2757714

Bridge Functionality Relationships for Improved Seismic Risk Assessment of Transportation Networks

Abstract: Relationships between bridge damage and the resulting loss of functionality of the bridge are critical to assessing the impact of an earthquake event on the performance of the transportation network. This study addresses this data need by use of a Web-based survey of central and southeastern U.S. Department ofTransportation bridge inspectors and officials. Results of the 28 responses are analyzed and offer a link between various types of bridge component damage and the expected level of allowable traffic carrying capacity due to closure decisions and repair procedures.This data is utilized to assess the probability of meeting various damage states, expressed in terms of restoration of functionality, and subsequently facilitate the refinement of component limit-state capacities for analytical fragility curve development. The bridge functionality relationships and methodology outlined serve as the basis for refinement of critical tools in the seismic risk assessment framework and improved assessment of transportation network performance. DOI: 10.1193/1.2431209

On Ground Motion Intensity Indices

Abstract: The characterization of strength of earthquake demands for seismic analysis or design requires the specification of a level of intensity. Numerous ground motion intensity indices that have been proposed over the years are being used for normalizing or scaling earthquake records regardless of their efficiency. An essential point of this study is that a ground motion index is appropriate, or efficient, as long as it can predict the level of structural response. This study presents correlations between 23 ground motion intensity indices and four response variables: elastic and inelastic deformation demands, and input energy and hysteretic energy; nonlinear responses are computed using elastoplastic, bilinear, and bilinear with stiffness degradation models. As expected, no index is found to be satisfactory over the entire frequency range. Indeed, indices related to ground acceleration rank better in the acceleration-sensitive region of the spectrum; indices based on ground velocity are better in the ...

Seismic fragility of suspended ceiling systems

Abstract: Full-scale dynamic testing of suspended ceiling systems was performed to obtain fragility data suitable for performance-based assessment and design. On the basis of the fragility data derived from testing, (1) the use of retainer clips improves the performance of ceiling systems in terms of loss of tiles, (2) including recycled cross tees in the suspension grid increases the vulnerability of the ceiling systems, (3) undersized (poorly fitting) tiles are substantially more vulnerable than properly fitted tiles, and (4) the use of compression posts improves the seismic performance of ceiling systems for the limit states of minor and moderate damage. Fragility curves are provided for four damage states.

Dynamics of Structures—Theory and Applications to Earthquake Engineering, Third Edition

Abstract: Previous editions of Anil Chopra’s Dynamics of Structures set the standard as textbook of choice for teaching structural dynamics with an eye to earthquake engineering. This third edition has come out nearly eleven years after the first hit the bookshelves, and what a fruitful decade this has been for earthquake engineering (see review of the second edition in Earthquake Spectra 17, 549). Performance-based earthquake engineering, which was in its infancy when the first edition of this book was published, is now entering its second generation. Application of nonlinear dynamics, which was limited to small academic circles and graduate studies, is now center stage for evaluation and design of major structures. Today, hardly any serious evaluation or retrofit of a substantial building is complete without at least considering either static or dynamic nonlinear analyses. The revisions included in the third edition of Dynamics of Structures reflect the changing characteristics of structural dynamics as applied in practice; as such, this book can be useful in teaching future engineers what they need to know to hit the ground running when they graduate. As previous editions did, the book can also serve as a comprehensive reference on the subject for practicing engineers who need to understand old as well as cutting-edge topics of structural dynamics. The major revisions to the book are reflected in Part III, the section that covers earthquake response and design of multistory buildings. In particular, Chapter 19, which deals with earthquake analysis and response of inelastic buildings, has been completely rewritten. In the second edition, this chapter contained only 23 pages; in this edition it has been expanded to 60 pages. Furthermore, the chapter has been divided into two separate parts. The first part covers what has been traditionally referred to as nonlinear time-history analysis, which is recently and more accurately referred to as nonlinear response-history analysis. The second part deals with approximate methods of nonlinear analysis consisting of various pushover analysis techniques, including modal pushover analysis, for which the author has been one of the leading pioneers. Based on structural dynamics theory, the modal pushover analysis procedure is developed and its accuracy evaluated. Chapter 21, which deals with various building code interpretations of structural dynamics principles, has also been significantly revised and enhanced, and now includes explanation and discussion of the relevant provisions of the 2006 International Building Code, 2005 National Building Code of Canada, 2004 Mexico Federal District Code, and 2004 Eurocode 8. New in the third edition, Chapter 22 discusses methods for estimating seismic demands promulgated in performance-based guidelines for evaluat-

Explicit Directivity-Pulse Inclusion in Probabilistic Seismic Hazard Analysis

Abstract: Probabilistic seismic hazard analysis (PSHA) is widely used to estimate the ground motion intensity that should be considered when assessing a structure’s performance. Disaggregation of PSHA is often used to identify representative ground motions in terms of magnitude and distance for structural analysis. Forward directivity–induced velocity pulses, which may occur in near-fault (or near-source) motions, are known to cause relatively severe elastic and inelastic response in structures of certain periods. Here, the principles of PSHA are extended to incorporate the possible occurrence of a velocity pulse in a near-fault ground motion. For each magnitude and sitesource geometry, the probability of occurrence of a pulse is considered along with the probability distribution of the pulse period given that a pulse does occur. A near-source “narrowband” attenuation law modification to predict ground motion spectral accelerationSa amplitude that takes advantage of this additional pulse period information is utilized. Further, disaggregation results provide the probability that a given level of ground motion intensity is caused by a pulse-like ground motion, as well as the conditional probability distribution of the pulse period associated with that ground motion. These extensions improve the accuracy of PSHA for sites located near faults, as well as provide a rational basis for selecting appropriate near-fault ground motions to be used in the dynamic analyses of a structure. DOI: 10.1193/1.2790487

Uncertainty and Correlation for Loss Assessment of Spatially Distributed Systems

Abstract: Seismic risk assessment for a spatially distributed system, such as a lifeline network, involves characterization of ground shaking and structural damage for multiple structures in a region. The expected value of monetary loss, a common measure of the risk, has been previously formulated but with little attention to the uncertainty around this monetary loss. Furthermore, prior research on risk assessment for lifeline systems, in particular transportation networks, assumes no spatial ground motion correlation and no structure-to-structure damage correlation between sites in the network. In this paper, a framework for treating these correlations in the network risk analysis is presented. A demonstration of this methodology is carried out for two transportation networks located in the San Francisco Bay region. Coefficients of variation for network physical loss using a non–distance dependent ground motion correlation model in the framework range between 0.6 and 1.5 for the sample networks presented ...

A Prioritization Scheme for Seismic Intervention in School Buildings in Italy

Abstract: A seismic rehabilitation program is being implemented to address the vulnerability of a large proportion of Italian building stock. A risk-management framework, initially only for Italian school buildings, has been developed to assign priorities for the rehabilitation, and to give timescales within which retrofit or demolition must take place. Since it is not practical to carry out detailed assessment for around 60,000 Italian schools, the framework is a multiple-level procedure that aims to identify the highest-risk buildings based on filters of increasing detail, and reduces the size of the building inventory at each step. Finally, priorities and timescales are assigned based on vulnerability, seismic hazard, and building occupancy, within a general framework with parameters that must be assigned by the relevant authorities. The methodology is transparent, technically based, and flexible enough to be adapted for other building types or regions.

Fragility Assessment of Steel Frames Using Neural Networks

Abstract: A neural network–based methodology is proposed for the rapid evaluation of the seismic demand using data extracted from ground motion records. Limit-state fragilities for a moment-resisting steel frame are developed using Monte Carlo simulation. The proposed methodology allows taking into account uncertainties on both structural capacity and seismic demand with reduced computational cost. The use of neural networks is motivated by the approximate concepts inherent in the fragility assessment and the large number of time-consuming nonlinear response history analyses required for the accurate calculation of the probability of a limit-state being exceeded. The trained neural network is used to obtain the level of seismic demand, which is expressed in terms of maximum interstory drift. The methodology proposed is efficient and general in application.

A Screening Procedure for Seismic Risk Assessment in Urban Building Stocks

Abstract: An effective step for seismic risk mitigation in large urban areas under high seismic risk is to identify the most vulnerable buildings that may sustain significant damage during a future earthquak...

Review of Seismic Codes on Liquid- Containing Tanks

Abstract: Liquid storage tanks generally possess lower energy-dissipating capacity than conventional buildings. During lateral seismic excitation, tanks are subjected to hydrodynamic forces. These two aspects are recognized by most seismic codes on liquid storage tanks and, accordingly, provisions specify higher seismic forces than buildings and require modeling of hydrodynamic forces in analysis. In this paper, provisions of ten seismic codes on tanks are reviewed and compared. This review has revealed that there are significant differences among these codes on design seismic forces for various types of tanks. Reasons for these differences are critically examined and the need for a unified approach for seismic design of tanks is highlighted. DOI: 10.1193/1.2428341

Effects of Seasonal Freezing on Bridge Column–Foundation–Soil Interaction and Their Implications

Abstract: Several seismic regions around the world experience seasonal freezing that can drastically alter the soil-foundation-structure interaction and structural response under earthquake loads. This paper analytically investigates the effects of seasonal freezing on lateral load response of a bridge column supported by a cast-in-drilled-hole CIDH foundation shaft. Accounting for the temperature effects on materials, the analyses were conducted at ambient temperatures of 23° C, �1°C , �7°C , �10°C , and �20°C , and the results obtained at 23° C and �10°C were validated using experimental data. In comparison to the response at 23° C, the response of the column-shaft system in the range of �1°C to �20°C exhibited 40%–188% increase in the effective elastic stiffness, 17%–63% reduction in the lateral displacement capacity, 0.54– 0.82 m upward shift in the maximum moment location, 25%–30% increase in the column shear demand, and 25%–80% increase in shear and 19%–68% reduction in the length of the plastic region in the CIDH shaft. DOI: 10.1193/1.2423071

Fragility Functions for Modern Reinforced-Concrete Beam-Column Joints

Abstract: Fragility functions are developed to predict the method of repair required for modern reinforced-concrete beam-column building joints subjected to earthquake loading. These fragility functions, in combination with similar fragility functions developed previously for older joints, are used to compare damage progression in older versus modern joints. To develop fragility functions for modern joints, the results of previous experimental investigations are used to generate empirical relationships between damage and earthquake demand, damage states are linked deterministically with commonly employed methods of repair, and the empirical data are modeled using a standard probability distribution. The demand parameters, damage states, methods of repair, and probability distribution used in the current study are chosen to facilitate comparison with results from the previous study. The results of this study are a family of fragility functions that can be used to predict the method of repair required for a ...

Ground Motion Attenuation Model for Peak Horizontal Acceleration from Shallow Crustal Earthquakes

Abstract: Spatial distribution of ground motion data of recent earthquakes unveiled some features of peak ground acceleration (PGA) attenuation with respect to closest distance to the fault R that current predictive models may not effectively capture. As such, PGA: (1) remains constant in the near-fault area, (2) may show an increase in amplitudes at a certain distance of about 3–1 0 km from the fault rupture, (3) attenuates with slope of R �1 and faster at farther distances, and (4) intensifies at certain distances due to basin effect (if basin is present). A new ground motion attenuation model is developed using a comprehensive set of ground motion data compiled from shallow crustal earthquakes. A novel feature of the predictive model is its new functional form structured on the transfer function of a single-degree-of-freedom oscillator whereby frequency square term is replaced with closest distance to the fault. We are proposing to fit ground motion amplitudes to a shape of a response function of a series (cascade) of filters, stacked separately one after another, instead of fitting an attenuation curve to a prescribed empirical expression. In this mathematical model each filter represents a separate physical effect. DOI: 10.1193/1.2755949

The Impact of High-Frequency/ Low-Energy Seismic Waves on Unreinforced Masonry

Abstract: Traditionally, the high-frequency components of earthquake loading are disregarded as a source of structural damage because their energy content is small and their frequency is too high to resonate with the natural frequencies of structures. We argue that higher-frequency waves traveling through stiff masonry structures can trigger two types of failure mechanisms that have not yet been taken into account. First, the high frequencies can cause small vertical interstone vibrations that result in irreversible relative displacements of the stones, which may ultimately lead to collapse. The energy needed to cause this deformation and failure comes largely from gravitational forces. Second, the partial fluidification and densification of the loose, granular inner core of some unreinforced masonry walls results in an increase of outward thrust. Preliminary results of a series of static and dynamic tests, as well as numerical models, demonstrate the potentially destructive effects of high-frequency/low-e...

Forecasting Probabilistic Seismic Shaking for Greater Tokyo from 400 Years of Intensity Observations

Abstract: The long recorded history of earthquakes in Japan affords an opportunity to forecast seismic shaking exclusively from past shaking. We calculate the time-averaged (Poisson) probability of severe shaking by using more than 10,000 intensity observations recorded since AD 1600 in a 350 km-wide box centered on Tokyo. Unlike other hazard-assessment methods, source and site effects are included without modeling, and we do not need to know the size or location of any earthquake nor the location and slip rate of any fault. The two key assumptions are that the slope of the observed frequency-intensity relation at every site is the same, and that the 400-year record is long enough to encompass the full range of seismic behavior. Tests we conduct here suggest that both assumptions are sound. The resulting 30-year probability of I JMA 6 shaking (PGA 0.4 g or MMI IX) is 30%–40% in Tokyo, Kawasaki, and Yokohama, and 10%–15% in Chiba and Tsukuba. This result means that there is a 30% chance that 4 million people will be subjected to IJMA 6 shaking during an average 30-year period. We also produce exceedance maps of PGA for building-code regulations, and calculate short-term hazard associated with a hypothetical catastrophe bond. Our results resemble an independent assessment developed from conventional seismic hazard analysis for greater Tokyo. DOI: 10.1193/1.2753504

Assessment of ASCE 41 Height-to-Thickness Ratio Limits for URM Walls

Abstract: Unreinforced masonry (URM) walls with sufficient anchorage to the diaphragms will crack above mid-height when subjected to out-of-plane ground motions. This study investigates the sensitivity of the out-of-plane response to varying height-to-thickness (h∕t) ratios for URM walls connected to rigid diaphragms. ASCE 41, Seismic Rehabilitation Standard, provides guidelines for permissible h∕t ratios for out-of-plane URM walls. To assess these limits, a rigid-body numerical model, calibrated to full-scale shake table tests, was used. The focus of the analysis was to identify the minimum h∕t ratio that would cause collapse of the wall when subjected to seismic shaking. The analysis was performed for 80 input motions and accounted for variability in the crack location. The results of the study suggest that the probability of collapse is dependent on the site class and that walls with limited overburden and satisfying the h∕t limits in ASCE 41 have a very low probability of collapse.

Analytical Estimation of Economic Loss for Buildings in the Area Struck by the 1999 Athens Earthquake and Comparison with Statistical Repair Costs

Abstract: Reliable loss assessment (in monetary terms) for buildings struck by an earthquake is an essential factor in the development of seismic risk scenarios for a given urban area. The evaluation of loss due to building damage in a certain region depends both on seismic hazard and the vulnerability of the building stock in the area.The study presented herein consists of predicting the loss to selected groups of buildings struck by the 1999 Athens earthquake using an analytical methodology and comparison with statistical repair costs collected after the earthquake. Since no near-field strong ground motion recordings from the main shock were available, a pilot methodology was used for its analytical evaluation for different soil conditions. Different suites of motions were derived, based on various theoretical and semi-empirical approaches, and were then used in analytical investigations of the seismic behavior of the buildings in the examined area, aiming at the prediction of economic losses. An in-situ survey of about 10% of the total building stock was performed, and data regarding the structural type, actual earthquake damage, and corresponding repair costs were collected. The statistically derived repair cost for the area was compared with the economic loss estimation obtained using the analytical procedure and various estimates of the seismic action in the area considered, and was found to agree with it reasonably for some of the seismic hazard scenarios. DOI: 10.1193/1.2720366

Post-earthquake Prioritization of Bridge Inspections

Abstract: Bridge damage reports from the 2001 Nisqually earthquake were correlated with estimates of ground-motion intensity at each bridge site (obtained from ShakeMaps) and with bridge properties listed in the Washington State Bridge Inventory. Of the ground-motion parameters considered, the percentage of bridges damaged correlated best with the spectral acceleration at a period of 0.3 s. Bridges constructed before the 1940s, movable bridges, and older trusses were particularly vulnerable. These bridge types were underestimated by the HAZUS procedure, which categorizes movable bridges and older trusses as “other” bridges. An inspection prioritization strategy was developed that combines ShakeMaps, the bridge inventory and newly developed fragility curves. For the Nisqually earthquake, this prioritization strategy would have made it possible to identify 80% of the moderately damaged bridges by inspecting only 481 (14%) of the 3,407 bridges within the boundaries of the ShakeMap. To identify these bridges u...

Macroseismic Study of the Zemmouri Earthquake of 21 May 2003 (Mw 6.8, Algeria):

Abstract: The 21 May 2003 Zemmouri earthquake (Mw=6.8), which killed 2,278 people, injured 11,450, made 250,000 homeless, and destroyed or seriously damaged 6,000 buildings and 20,800 housing units, is the most significant earthquake to affect Algeria since the 1980 El Asnam earthquake (Ms=7.3). This paper presents the report of the macroseismic survey conducted by the Centre of Research in Astronomy, Astrophysics, and Geophysics (CRAAG, Algeria) immediately after the earthquake. The collected data set has led to a comprehensive evaluation of damage and estimation of intensity at about 600 sites, a number never reached in previous earthquake damage surveys. The produced isoseismal map portrays the spatial distribution of intensities from III to X EMS. A map highlighting the damage distribution, where various geological and hydrological phenomena are reported, is also presented. The extent of the socioeconomic impact of this event confirmed that Algerian buildings are highly vulnerable to the recurrence of ...

Seismic Strengthening of Reinforced-Concrete Multicolumn Bridge Piers

Abstract: The analysis, seismic rehabilitation measures, and in-situ performance of a reinforced-concrete (RC) bridge pier subjected to quasi-static loads are presented. The bridge was built in 1963 and was ...

In-Plane Shake-Table Testing of GFRP- Strengthened Concrete Masonry Walls

Abstract: In-plane shake-table tests were performed on eight full-scale unreinforced concrete block walls. Three of the walls were left as plain unreinforced masonry and five were strengthened using glass-fiber-reinforced plastic (GFRP) strips in four different configurations. All walls were first subjected to design-level earthquake records to determine the improvement obtained from the addition of the GFRP. The walls were then subjected to extreme-level earthquake records to examine the ultimate failure modes and the effects of the various GFRP configurations on the response of the walls. It was observed that all strengthened specimens performed well during the design-level shaking, and three of the four GFRP configurations also performed well during the extreme-level shaking. The tests showed that the use of vertical GFRP strips alone is able to improve the in-plane performance of URM walls. The strips were also able to control the failure modes, and prevent collapse after severe damage, improving signi...

A Probe into the Seismic History of Athens, Greece from the Current State of a Classical Monument

Abstract: Based on the current deformation of a column of the temple of Olympios Zeus (Olympieion) in Athens, Greece, a backward analysis is performed in an effort to investigate the seismic history of the a...

Shallow P- and S-Wave Velocities and Site Resonances in the St. Louis Region, Missouri-Illinois

Abstract: As part of the seismic hazard–mapping efforts in the St. Louis metropolitan area we determined the compressional and shear-wave velocities (Vp and Vs) to about a 40-m depth at 17 locations in this area. The Vs measurements were made using high-resolution seismic refraction and reflection methods. We find a clear difference in the Vs profiles between sites located on the river floodplains and those located in the upland urban areas of St. Louis. Vs30 (average Vs to 30-m depth) values in floodplain areas range from 200 to 290 m∕s (NEHRP category D) and contrast with sites on the upland areas of St. Louis, which have Vs30 values ranging from 410 to 785 m∕s (NEHRP categories C and B). The lower Vs30 values and earthquake recordings in the floodplains suggest a greater potential for stronger and more prolonged ground shaking in an earthquake. Spectral analysis of a M3.6 earthquake recorded on the St. Louis–area ANSS seismograph network indicates stronger shaking and potentially damaging S-wave resonan...

"Istanbul at the Threshold: An Evaluation of the Seismic Risk in Istanbul"

Abstract: There is no convincing evidence indicating that future ground motion in at least two-thirds of Istanbul, Turkey, shall be less demanding than the ground motions that devastated the city of Duzce, Turkey, in 1999. Comparison of vulnerability indices calibrated for Turkish construction indicates that the structures of the buildings in Istanbul are no better than the structures of buildings in Duzce. On the basis of these arguments, we project that a future earthquake near Istanbul may cause severe damage or collapse approximately quarter of a million buildings. Leaving the vulnerable buildings as they are and organizing for emergency response is not an option for Istanbul. DOI: 10.1193/1.2424988