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The range of response frequencies for which spectral ordinates obtained from accelerograms may be considered reliable is limited by several factors, primary among them being the effects of filters that are routinely applied to remove noise from the records. Considerable attention has been focused on the low-frequency limit of the usable spectral ordinates because of various engineering applications requiring long-period spectral accelerations or displacements but only recently have rational approaches to selecting the high-frequency limit been proposed. Since there are applications for which the high-frequency spectral ordinates are important, the approaches to this issue presented in the recent studies are reviewed and their application to the ground-motion database from Europe and the Middle East is explored. On the basis of the results of these analyses, it is concluded that a large proportion of this dataset can be used to provide reliable estimates of response spectral ordinates at much shorter periods than may have previously been considered feasible. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Over the history of instrumental strong-motion recording, the largest amplitudes of ground motions recorded to date have had a significant impact on the perception of the largest amplitudes of ground motion considered physically realizable. However, the length of the instrumental recording history is comparatively short, and instrumental recording networks are relatively sparse, which raises the issue of whether the full range of ground motions has been captured in the current global holdings of strong-motion data. Because the answer to this question is quite obviously negative, a more difficult question then arises: How much greater than the largest currently available observation could future ground motions be? The present article explores this issue, drawing on empirical observations, results from numerical simulations, and a statistical exercise involving the sampling of spatially correlated stochastic ground-motion fields. [ABSTRACT FROM AUTHOR]

This article summarizes recent work investigating the sensitivity of loss estimates for the northern Marmara region to various representations of ground-motion variability. Issues that are discussed include the partitioning of the total ground-motion variability into inter- and intra-event components, macrospatial correlations among ground motions, and the propagation of the ground-motion variability into damage and loss calculations. The issue of whether an earthquake loss model can be validated using field observations is also considered. Recent findings suggest that, regardless of how one treats the ground-motion variability when conducting loss estimation analyses, unless a close network of accelerograms and a high spatial resolution of exposure data exists, the ground-motion variability precludes the validation of loss models. [ABSTRACT FROM AUTHOR]

Peak ground velocity (PGV) has many applications in earthquake engineering, but there are relatively few prediction equations for this parameter in comparison with the large numbers of equations for estimating peak ground acceleration and response spectral ordinates. This lack of empirical equations for PGV has led to widespread use of the practice of scaling peak velocity from the 5%-damped response spectral ordinate at 1 sec, which is a poor substitute for direct prediction of the parameter. Responding to the need to provide equations for the prediction of PGV, this article derives new equations using the strong-motion database for the seismically active areas of Europe and the Middle East, following a new processing of all of the records. A total of 532 strong-motion accelerograms recorded at distances of up to 100 km from 131 earthquakes with moment magnitudes ranging from M 5 to 7.6 are used to derive equations for both the larger and the geometric mean of the horizontal components. The predictions are found to be broadly consistent with those from previous European equations, and also with preliminary results from the Next Generation of Attenuation (NGA) project, suggesting that systematic differences in ground motions from active crustal regions, if any, are sufficiently small not to prevent the combined use of strong-motion data from southern Europe, western North America, and other tectonically active areas of shallow crustal seismicity. [ABSTRACT FROM AUTHOR]

The basic elements of probabilistic seismic-hazard analysis (PSHA) were established almost four decades ago and PSHA has now become the most widely used approach for estimating seismic-design loads. Although the use of PSHA is widespread, considerable confusion remains regarding the details of how the calculations should be performed. This situation is largely a result of the way the discipline of PSHA evolved through a series of articles, reports, and software packages. This article demonstrates that the feature of PSHA about which there is perhaps the greatest degree of misunderstanding is the treatment of the aleatory variability in ground-motion prediction equations, which exerts a very pronounced influence on the calculated hazard. Probabilistic hazard studies performed in recent years have frequently resulted in appreciably higher design ground motions than had been obtained in previous assessments carried out in the 1970s and 1980s, often sparking controversial debate. Although several factors may contribute to the higher estimates of seismic hazard in modern studies, the main reason for these increases is that in the earlier studies the ground-motion variability was either completely neglected or treated in a way that artificially reduced its influence on the hazard estimates. [ABSTRACT FROM AUTHOR]

Peak ground velocity (PGV) has received much less attention in the technical literature than more widely-used parameters such as peak ground acceleration (PGA) and response spectral ordinates. However, there are many examples of the use of PGV in engineering seismology and earthquake engineering, including as a parameter from which to estimate macroseismic intensity and structural damage. PGV is also employed in some methods for the assessment of liquefaction potential and, because of its relationship to ground strains, in the seismic design and assessment of buried pipelines. One of the most important uses of PGV has been in the construction of elastic response spectra. There are relatively few predictive equations for PGV, compared to those for PGA and spectral ordinates, but 25 such equations are reviewed and summarised. The issue of scaling PGV from response spectral ordinates is explored and it is shown that the common practice of scaling PGV from spectral accelerations at 1.0 second should not be continued because the ratio of the two quantities is highly variable. A more stable relationship exists between PGV and the spectral acceleration at 0.5 second response period; however, it is clearly preferable to estimate peak velocities directly and PGV equations should be derived together with equations for spectral ordinates in the same way as PGA. [ABSTRACT FROM AUTHOR]

Abstract: Recordings from strong-motion accelerographs are of fundamental importance in earthquake engineering, forming the basis for all characterizations of ground shaking employed for seismic design. The recordings, particularly those from analog instruments, invariably contain noise that can mask and distort the ground-motion signal at both high and low frequencies. For any application of recorded accelerograms in engineering seismology or earthquake engineering, it is important to identify the presence of this noise in the digitized time-history and its influence on the parameters that are to be derived from the records. If the parameters of interest are affected by noise then appropriate processing needs to be applied to the records, although it must be accepted from the outset that it is generally not possible to recover the actual ground motion over a wide range of frequencies. There are many schemes available for processing strong-motion data and it is important to be aware of the merits and pitfalls associated with each option. Equally important is to appreciate the effects of the procedures on the records in order to avoid errors in the interpretation and use of the results. Options for processing strong-motion accelerograms are presented, discussed and evaluated from the perspective of engineering application. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

The seismic hazard and risk analysis for the onshore Groningen gas field requires information about local soil properties, in particular shear-wave velocity (VS). A fieldwork campaign was conducted at 18 surface accelerograph stations of the monitoring network. The subsurface in the region consists of unconsolidated sediments and is heterogeneous in composition and properties. A range of different methods was applied to acquire in situ VS values to a target depth of at least 30 m. The techniques include seismic cone penetration tests (SCPT) with varying source offsets, multichannel analysis of surface waves (MASW) on Rayleigh waves with different processing approaches, microtremor array, cross-hole tomography and suspension P-S logging. The offset SCPT, cross-hole tomography and common midpoint cross-correlation (CMPcc) processing of MASW data all revealed lateral variations on length scales of several to tens of metres in this geological setting. SCPTs resulted in very detailed VS profiles with depth, but represent point measurements in a heterogeneous environment. The MASW results represent VS information on a larger spatial scale and smooth some of the heterogeneity encountered at the sites. The combination of MASW and SCPT proved to be a powerful and cost-effective approach in determining representative VS profiles at the accelerograph station sites. The measured VS profiles correspond well with the modelled profiles and they significantly enhance the ground motion model derivation. The similarity between the theoretical transfer function from the VS profile and the observed amplification from vertical array stations is also excellent. [ABSTRACT FROM AUTHOR]