Zeynep Gülerce

Site-Specific Design Spectra for Vertical Ground Motion

This paper contains ground-motion prediction equations (GMPEs) for the vertical-to-horizontal spectral acceleration (V/H) ratio, and the methods for constructing vertical design spectra that are consistent with the probabilistic seismic hazard assessment results for the horizontal ground motion component. The GMPEs for V/H ratio consistent with the horizontal GMPE of Abrahamson and Silva (2008) are derived using the Pacific Earthquake Engineering Research Centers Next Generation of Ground-Motion Attenuation Models (PEER-NGA) database (Chiou et. al. 2008). The proposed V/H ratio GMPE is dependent on the earthquake magnitude and distance, consistent with previous models, but it differs from previous studies in that it accounts for the differences in the nonlinear site-response effects on the horizontal and vertical components. This difference in nonlinear effects results in large V/H ratios at short spectral periods for soil sites located close to large earthquakes. A method to develop vertical design spectra dependent on the horizontal component uniform hazard spectrum that accounts for the correlation between the variability of the horizontal ground-motion model and the variability of the V/H ratio ground-motion model is proposed.

Vector-Valued Probabilistic Seismic Hazard Assessment for the Effects of Vertical Ground Motions on the Seismic Response of Highway Bridges

The vertical ground motion component is disregarded in the design of ordinary highway bridges in California, except for the bridges located in high seismic zones (sites with design horizontal peak ground acceleration greater than 0.6 g). The influence of vertical ground motion on the seismic response of single-bent, two-span highway bridges designed according to Caltrans Seismic Design Code (SDC-2006) is evaluated. A probabilistic seismic hazard framework is used to address the probability of exceeding the elastic capacity for various structural parameters when the vertical component is included. Negative mid-span moment demand is found to be the structural parameter that is most sensitive to vertical accelerations.A series of hazard curves for negative mid-span moment are developed for a suite of sites in Northern California. The annual probability of exceeding the elastic capacity of the negative mid-span moment is as large as 0.01 for the sites close to active faults when the vertical component is included. Simplified approaches based on the distance to major faults or the median design peak acceleration show that there is a large chance (0.4 to 0.65) of exceeding the elastic limit if the current 0.6 g threshold is used for the consideration of vertical ground motions for ordinary highway bridges. The results of this study provide the technical basis for consideration of a revision of the 0.6 g threshold.

Turkey-Adjusted NGA-W1 Horizontal Ground Motion Prediction Models

The objective of this paper is to evaluate the differences between the Next Generation Attenuation: West-1 (NGA-W1) ground motion prediction models (GMPEs) and the Turkish strong ground motion data set and to modify the required pieces of the NGA-W1 models for applicability in Turkey. A comparison data set is compiled by including strong motions from earthquakes that occurred in Turkey and earthquake metadata of ground motions consistent with the NGA-W1 database. Random-effects regression is employed and plots of the residuals are used to evaluate the differences in magnitude, distance, and site amplification scaling. Incompatibilities between the NGA-W1 GMPEs and Turkish data set in small-to-moderate magnitude, large distance, and site effects scaling are encountered. The NGA-W1 GMPEs are modified for the misfit between the actual ground motions and the model predictions using adjustments functions. Turkey-adjusted NGA-W1 models are compatible with the regional strong ground motion characteristics and preserve the well-constrained features of the global models.

Effect of Seismic Source Model Parameters on the Probabilistic Seismic‐Hazard Assessment Results: A Case Study for the North Anatolian Fault Zone

The inputs to the probabilistic seismic‐hazard analysis (PSHA) contain large uncertainties regarding the seismic source model parameters; therefore, results may vary significantly due to subjective judgment and interpretation of the limited data. The objective of this study is to show the effect of seismic source models on the hazard results by quantifying the differences in the design ground motions for different hazard levels at different locations around the North Anatolian fault. Analysis showed the variances in the hazard results obtained by different seismic source models are closely correlated with the location of the site and hazard level. Additionally, sensitivity of the hazard results to the uncertainties involved in each source parameter, especially the source zone boundaries, annual slip rate, maximum and minimum magnitudes, fault width, b ‐value, and scenario weights are analyzed and presented to provide insight on the relative contribution of source or fault parameters to the PSHA results.

Ground Motion Prediction Equations for the Vertical Ground Motion Component Based on the NGA-W2 Database

Empirical ground motion models for the vertical component from shallow crustal earthquakes in active tectonic regions are derived using the PEER NGA-West2 database. The model is applicable to magnitudes 3.0–8.0, distances of 0–300 km, and spectral periods of 0–10 s. The model input parameters are the same as used by Abrahamson et al. (2014) except that the nonlinear site response and depth to bedrock effects are evaluated but found to be insignificant. Regional differences in large distance attenuation and site amplification scaling between California, Japan, China, Taiwan, Italy, and the Middle East are included. Scaling for the hanging-wall effect is incorporated using the constraints from numerical simulations by Donahue and Abrahamson (2014). The standard deviation is magnitude dependent with smaller magnitudes leading to larger standard deviations at short periods but smaller standard deviations at long periods. The vertical ground motion model developed in this study can be paired with the horizontal component model proposed by Abrahamson et al. (2014) to produce a V/H ratio. For applications where the horizontal spectrum is derived from the weighted average of several horizontal ground motion models, a V/H model derived directly from the V/H data (such as Gülerce and Abrahamson 2011) should be preferred.

Probabilistic Seismic‐Hazard Assessment for East Anatolian Fault Zone Using Planar Fault Source ModelsProbabilistic Seismic‐Hazard Assessment for East Anatolian Fault Zone Using Planar Fault Source Models

The objective of this article is to provide state-of-the-art probabilistic seismic-hazard assessment maps for the East Anatolian fault zone (EAFZ) based on planar seismic-source models and up-to-date ground-motion models. Development of fault-based seismic-source models requires the definition of source geometry in terms of fault length, fault width, fault-plane angles, and segmentation points for each segment of the EAFZ, building rupture systems that consider fault-to-fault ruptures and associating the observed seismicity with defined rupture systems. This complicated task was performed by compiling the seismotectonic characteristics of the EAFZ using available geological information and the instrumental earthquake catalogs of Turkey. Recently published global Next Generation Attenuation (NGA)-West2 groundmotion models (Bozorgnia et al., 2014) and Turkey-adjusted NGA-West1 models (Gülerce et al., 2016) are used in the ground-motion logic tree with equal weights. The results are presented in terms of the seismic-hazard maps for hazard levels in design codes for different spectral periods and for rock-like reference site conditions (VS30 760 and 1100 m=s).

BSHAP seismic source characterization models for the Western Balkan region

This manuscript presents the seismic source characterization models that were developed and used for the Western Balkan region in the framework of Harmonization of Seismic Hazard Maps in the Western Balkan Countries Project (BSHAP II) funded by NATO-Science for Peace and Security Program. Relevant knowledge about the geological and seismotectonic structure of Western Balkans and surrounding region was collected and utilized along with the BSHAP focal mechanism database and the BSHAP earthquake catalogue (Markušić et al. in Bull Earthq Eng 14(2):321–343, 2016. doi:10.1007/s10518-015-9833-z) to delineate seismic source models for different purposes. The super zone model of large zones bounds the regions with similar seismotectonic characteristics and catalogue completeness levels and was used for calculating the regional b-value of the magnitude recurrence relationship. Additionally, two models of smaller zones that represent the epistemic uncertainty in source geometry, maximum magnitude and style-of-faulting, were developed to be employed in the two-stage (circular and elliptical) smoothing procedure. Sets of sensitivity analyses are performed to support final estimates of some models’ parameters affecting the smoothed seismicity rate. The seismic source models and the logic-tree presented here are to be implemented in the probabilistic seismic hazard assessment for the seismic hazard maps of the Western Balkan region.

Reply to “Comment to BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region” by Carlo Cauzzi and Ezio Faccioli

This article is reply to the comment sent by Carlo Cauzzi and Ezio Faccioli related to the published article “BSHAP project strong ground motion database and selection of suitable ground motion models for the Western Balkan Region” by Salic et al. (2016).

Probabilistic Seismic Hazard Assessment of Seismically Induced Landslide for Bakacak-Dϋzce Region

Earthquake induced slope instability is considered as one of the major sources of the earthquake hazards, especially in the near fault regions. Simplified tools as Newmark’s Sliding Block (NSB) analogy are commonly used to represent the slope stability during ground shaking since the outcome of this analogy is quantitative, larger NSB displacement values indicate higher seismic slope instability risk. Recently, empirical NSB displacement prediction models based on single or multiple ground motion intensity measures are proposed to analyze the slope instability hazard in a probabilistic manner. Within the contents of this study, the most compatible NSB displacement model with the regional ground motion characteristics is selected and incorporated into the vector-valued probabilistic seismic hazard assessment framework. The NSB displacement hazard curves are constructed for Asarsuyu Region where a large-scaled seismically induced landslide was observed during 1999 Dϋzce earthquake. The NSB displacement hazard results are compared with the dynamic analysis results that were conducted immediately after the earthquake and measured slope displacements.

Planar seismic source characterization models developed for probabilistic seismic hazard assessment of Istanbul

This contribution provides an updated planar seismic source characterization (SSC) model to be used in the probabilistic seismic hazard assessment (PSHA) for Istanbul. It defines planar rupture systems for the four main segments of the North Anatolian fault zone (NAFZ) that are critical for the PSHA of Istanbul: segments covering the rupture zones of the 1999 Kocaeli and Düzce earthquakes, central Marmara, and Ganos/Saros segments. In each rupture system, the source geometry is defined in terms of fault length, fault width, fault plane attitude, and segmentation points. Activity rates and the magnitude recurrence models for each rupture system are established by considering geological and geodetic constraints and are tested based on the observed seismicity that is associated with the rupture system. Uncertainty in the SSC model parameters (e.g., b value, maximum magnitude, slip rate, weights of the rupture scenarios) is considered, whereas the uncertainty in the fault geometry is not included in the logic tree. To acknowledge the effect of earthquakes that are not associated with the defined rupture systems on the hazard, a background zone is introduced and the seismicity rates in the background zone are calculated using smoothed-seismicity approach. The state-of-the-art SSC model presented here is the first fully documented and readyto-use fault-based SSC model developed for the PSHA of Istanbul.