Updating seismic hazard models for Kuwait

The valuable results from this research are the first and essential step for assessing seismic risk in Kuwait. The increase in the urban development and construction of tall buildings and skyscrapers in Kuwait necessitated an estimate of the seismic risk for creating a unified seismic code for Kuwait. This research comes to make the necessarily step by assessing the seismic hazard and deaggregation in the State of Kuwait. For this purpose, the historical and instrumental seismic catalogs of Kuwait and the active Zagros Seismic Belt were primarily compiled, unifying the magnitudes, removing unnecessary earthquakes (seismicity declustering) and considering the completeness of the catalogs. Multi-seismotectonic models for Kuwait region incorporate earthquake focal mechanisms, seismicity pattern, and structural geological situation have been created to reduce epistemic uncertainty. The recurrence parameters as well as the maximum expected earthquake from each seismic source were fundamentally estimated. Appropriate ground motion attenuation relation within a logic tree formulation was mainly used in creating hazard maps. A state-of-the-art probabilistic approach is used herein to produce hazard maps at return periods of 75, 475, 975 and 2475 years (equivalent to 50%, 10%, 5% and 2%, respectively, probability of exceedance in 50 years) at periods of PGA, 0.1, 1 and 4 seconds. The computations of hazard maps were constructed using spacing grid of 0.2° × 0.2° all over the Kuwait area. Uniform hazard spectrum and deaggregation charts have been adopted for all six governorates of Kuwait. These results with vulnerability index are the main components for estimating the seismic risk of Kuwait.

Modified spectral format based on probability level using site-specific uniform hazard spectrum

Deficiencies of the four spectral formats i.e., 2%/50-yr, 5%/50-yr, 10%/50-yr and AASHTO (American Association of State Highway Officials) 2009 demand modification of the spectral formats for bridge design application in Canada. Among them the 10%/50-yr spectrum is dropped from current investigation as its difference with Canadian Highway Bridge Design Code (CHBDC) 2006 is too large to modify. This study introduces an approach calibrating on the values of elastic seismic response coefficient to provide a new shape of the Canadian bridge design spectrum based on modified 2%/50-yr, modified 5%/50-yr and modified AASHTO spectral formats. A Digital Visual Fortran program was prepared to determine the optimum values of the modification factors incorporated into the three spectral formats calibrated on the data of 389 cities of Canada. Thus, here it is developed the strategies of modifying the three spectral formats based on the best probability level for CHBDC using site-specific Uniform Hazard Spectrum (UHS). Finally, select the most suitable spectral format to apply for the design base shear calculations for the bridges of Canada.

Seismic Hazard Assessment for the Energy Facilities in Marmara Region

<p>Marmara region is a tectonically active part of Turkey. Over the history, the Marmara region has been the site of numerous destructive earthquakes such as the 1509 Istanbul earthquake (Mw=7.5), 1766 Istanbul earthquake (Mw=5.63), 1953 Yenice-Gönen Depremi (Ms=7.2), 1999 Kocaeli (Mw=7.4) and Düzce (Mw=7.2) earthquakes. Many Electric power systems located in the Marmara region are exposed to the destructive effects of potential earthquakes. The serviceability and functionality of the electric power systems after a major earthquake are major concerns for people's wealth. Thus, the design of the electric power system requires site-specific seismic hazard assessment. Site-specific hazard analysis provides a uniform hazard spectrum used for the design of power structures. Response spectrums are presented for the seismically resistant design of the structures according to the Turkey Building Earthquake Regulation 2018 (TBDY2018) and Turkish Seismic Code 2007 (TSC2007) regulations. <br>In this study, seismic hazard assessment of the Marmara region has been studied using the Openquake platform. Earthquake hazard has been investigated using the time-independent probabilistic (Poisson) models. Probabilistic seismic hazard assessment (PSHA) is conducted based on SHARE project ESHM13 model characteristics. The SHARE project has presented the 2013 European –Mediterranean seismic hazard model (ESHM13). ESHM13  models consist of all events with magnitudes Mw>=4.5 in the computation of seismic hazard and it covers the whole European territory including Turkey. The probabilistic seismic hazard assessment calculations take into account SHARE seismic source characterization. Akkar&Bommer(2010), Cauzzi&Faccioli(2008), Chiou&Youngs(2008), and Zhao et.al (2006) ground motion prediction models have been considered for active shallow crustal tectonic region. The study has developed uniform hazard spectrum and hazard maps of the Marmara Region with peak ground acceleration (PGA) and spectral accelerations (SA)’s at 0.2s and 1s periods corresponding to 10% and 2% probabilities of exceedance in 50 years. Obtained uniform hazard spectrums of electric power systems in the Marmara region have been compared with response spectrums of TBDY2018 and TSC-2007. The compatibility of SHARE model hazard analysis results with TBDY 2018 and TSC2007 has been assessed.</p>

Selecting, scaling, and orienting three components of ground motions for intensity-based assessments at far-field sites

This article develops a methodology for selecting, scaling, and orienting three orthogonal components of ground motion (GM) when conducting intensity-based assessments of structures. Target spectra for selecting multicomponent GMs are critically examined and strategies for selecting hazard-consistent GMs are investigated. The Conditional Mean Spectrum–Uniform Hazard Spectrum (CMS-UHS) Composite Spectrum is proposed as an alternative to several Conditional Mean Spectra for selecting multicomponent GMs when conducting intensity-based assessments of complex three-dimensional (3D) structures. To ensure hazard consistency, multicomponent GMs should be selected using (a) the target spectrum for the vertical component of GM, (b) a wide range of vibration periods, and (c) scale factors that are constrained. With constrained scale factors, all three components of a GM can be reasonably scaled either by the same scale factor or by different scale factors.

Earthquake Risk Analysis and Qualitative Comparison of Attenuation Relationships in Garmsar City, Iran

Despite the scientists’ wide efforts to determine earthquake risks all around the world, it is not still possible to predict the exact time, location and magnitude of future earthquakes and aftershocks at the ground surface so precise results are not predictable within near future. The most significant reason for this relates to numerous complexities of earthquake mechanism and causal conditions and waves through different ground layers with completely different properties. Logical tree method was used with weights to determine acceleration spectra due to spectral nature of region. Probabilistic analysis of earthquake hazard was done using SEISRISK III program. The analysis results are proposed through spectral acceleration maps for 50 years in Garmsar. Moreover, uniform hazard spectrum and spectrum with constant shape are presented.

Generation of Uniform Hazard Spectrum Based on the Stochastic Method of Simulating Ground Motion and Its Use in Nuclear Power Plants

To obtain an accurate uniform hazard spectrum (UHS), this paper proposes combining a stochastic simulation with probabilistic seismic hazard analysis. The stochastic method fully accounts for the effect of the source mechanism, path, and site effect. Historical ground motions in the site specific to the nuclear power plant (NPP) are simulated, and a UHS with an equal exceeding probability is proposed. To compare the seismic performance of the NPP under different ground motions generated by the existing site spectrum (SL-2), the UHS generated by the safety evaluation report, and the US RG1.60 spectrum, respectively, a three-dimensional finite element model is established, and dynamic analysis is performed. Results show that the structural responses to different spectra varied; the UHS response was slightly larger than that of RG1.60. This finding is relatively more reasonable than prior research results. The UHS generated using the stochastic simulation method can provide a reference for the seismic design of NPPs.

Exploring Risk-Targeted Hazard Maps for Europe

In Europe, the design of new structures according to modern regulations requires a uniform hazard spectrum for a given return period (e.g., 475 years). The assumption is that the resulting collapse probability is equally uniform for all structures, regardless of their structural properties or location. However, the uncertainty in the collapse capacity and hazard curves at different sites lead to an unequal level of risk. This discrepancy is undesirable given that some inhabitants will live in dwellings with a lower seismic safety than others living in structures designed according to the same regulation. The estimation of risk-targeted hazard maps allows for the definition of a design ground motion leading to a uniform level of risk. Using hundreds of fragility models developed for European buildings and hazard results from the SHARE project, we calculate risk-targeted hazard maps for a pre-established annual collapse probability.