Updated Seismic Hazard Research Articles

Seismic Hazard in Greece: A Comparative Study for the Region of East Macedonia and Thrace

Greece is located in one of the most seismically active regions in Europe. Many seismic hazard studies have been performed for various sites around Greece, at a regional or local scale. However, the latest national seismic hazard map, currently used for the seismic design of buildings and infrastructure, was published in 2000 and has not been updated since then. In light of recent advances in seismic source and ground motion modeling, the present study focuses on a comparative Probabilistic Seismic Hazard Assessment (PSHA) for the region of East Macedonia and Thrace (EMTH), located in Northern Greece. Various seismic source models are implemented and compared against an updated earthquake catalog to form the necessary source model logic tree. The ground motion logic tree is composed of Ground Motion Prediction Equations (GMPEs), which have been proven suitable for implementation in Greece. PSHA results are presented for the most important cities of East Macedonia and Thrace in a comparative way, which highlights the variability of the seismic hazard among the various seismic source models. An updated seismic hazard map of the study area is proposed, and a comparative disaggregation analysis is performed to estimate the earthquake scenarios with the largest contribution to the seismic hazard.

Updated seismic hazard curves, maps, and spectra for the northern Dominican Republic using a probabilistic seismic hazard analysis

This article presents updated seismic hazard curves, spectra, and maps of ground motion intensity measures for the northern region of the Dominican Republic (DR) obtained using a probabilistic seismic hazard analysis (PSHA). The analysis performed uses as input data an earthquake recurrence model based on fault slip rates derived from GPS measurements published in the aftermath of the 2010 Haiti earthquake. The seismicity rate data are used to calibrate a composite characteristic earthquake model, which is combined with a Poisson process to provide a temporal characterization of earthquake occurrence. The seismic hazard curves and maps presented include parameters such as (horizontal) peak ground acceleration and pseudo-spectral response accelerations at 0.2s and 1.0s periods for 5% damping at firm rock sites. The results show that the ground motion parameters with a 2% probability of exceedance (PE) in 50 years determined in this study are up to 46% larger than the corresponding parameters specified in the current DR building code seismic hazard maps for the northern DR. Moreover, the design response spectra for a site in the city of Santiago specified in the code is significantly lower than the 2% PE in 50 years uniform hazard spectra determined in this study for vibration periods smaller than 0.5s, a range that includes the majority of the structures that define the built environment of the DR.

Simplified methods to estimate mean hazard due to updated ground motion model: Application to nuclear power plants in CEUS

Two methods were developed to estimate updated mean seismic hazard for existing probabilistic seismic hazard analyses (PSHAs) due to a change in the ground motion model (GMM). Both methods were used to estimate updated hazard at nuclear power plant (NPP) sites in the Central and Eastern United States (CEUS) for a change from the Electric Power Research Institute (EPRI) 2013 GMM to the Next Generation Attenuation (NGA)-East GMM. These methods present efficient tools to inform decisions on whether to perform a full PSHA revision or other detailed evaluations, especially when a large number of sites must be analyzed. A Simplified Hazard (SiHaz) method was developed to estimate mean hazard explicitly using a reduced PSHA logic tree that incorporates the updated GMM and potential changes in the site response model. An alternative scaling method was independently developed to be applied directly to current CEUS NPP hazard. Both methods were validated using updated PSHA results at several sites. Estimates at 46 NPP sites using both methods showed good agreement for mean annual frequencies of exceedance between 1E-4 and 1E-5/yr.

Performance based evaluation of an existing continuous reinforced concrete bridge – a case study

A performance-based evaluation was conducted on an eleven-span reinforced concrete bridge located in a high seismicity area. This bridge was designed using SNI 2833:1992 and to be checked using the updated Indonesian seismic hazard map. In addition, a non-linear time history analysis was conducted using eleven pairs of ground motions to evaluate the structural performance of the bridge pier for the anticipated service life. Elastic analysis shows that the existing bridge still satisfies the strength and serviceability requirement despite the increase in seismic demand. Meanwhile, by evaluating the average inelastic longitudinal reinforcement and concrete strain at bridge pier for selected eleven ground motions, this study suggests that the bridge is still “fully operational” and “life safety” when subjected to the lower level (100 year return period) and upper level (1000 year return period) ground motions, respectively.

Probabilistic seismic hazard map analysis for Aceh Tenggara district and microzonation for Kutacane city

The Aceh Tenggara (Southeast Aceh) District, especially Kutacane, is located along with the main GSF (Great Sumatra Fault) system and the Tripa segment in particular based on seismic hazard map of Indonesia 2017. Therefore, the seismic hazard map needs to be updated based on the recent seismotectonic information and the latest active fault investigations. This paper discusses the updated seismic hazard map for the Aceh Tenggara district. In seismic hazard calculation, input source definition including fault characteristics, subduction zone, and seismicity background. Ground Motion Prediction Equation (GMPE) is used by the Indonesian official seismic hazard map 2017 to compute the hazard curve of strong ground shaking. Probability exceeding 2% and 10% for 50 years is chosen to calculate PGA (Peak Ground Acceleration) map on bedrock. On the other hand, Kutacane is located on a younger alluvium basin in the Holocene epoch thus site sediment amplification effect is taken into account in the microzonation calculations (local scale). The geomorphological slope is used to estimate the Vs30 distribution map. The site amplification is calculated based on PGA value on bedrock and Vs30 value on each site location. The Probabilistic Seismic Hazard Analysis (PSHA) is applied to produce seismic hazard maps as also used since many scientists and engineers in Indonesia although for critical infrastructure Neo-Deterministic Seismic Hazard Analysis (NDSHA) is suggested to be applied. The newly updated seismic hazard map can be used for the reference of infrastructure development in order to reduce the risk of disaster.

Seismic Risk Assessment of Safety-Critical Nuclear Facilities for the Purpose of Risk-Informed Periodic Reevaluation

Following U.S. Department of Energy Order 420.1 C for the mitigation of natural phenomena hazards, such as earthquakes, to nuclear facilities through periodic reassessments, Idaho National Laboratory (INL) has developed the Seismic Hazard Periodic Re-Evaluation Methodology (SHPRM). The SHPRM involves seven criteria that evaluate changes to the seismic hazard at a site due to changes in the input models/data over time. Should these changes to the seismic hazard result in an increase in the design or licensing-basis ground motion of the facility from that which the facility was designed for, the SHPRM includes a criterion for reevaluating the facility risk objectives. While the criteria corresponding to the reevaluation of the seismic hazard and the design basis have been previously demonstrated and published, there is currently no guidance on reevaluating seismic risk for the purpose of SHPRM. This paper complements the published reports and papers on the application of SHPRM by demonstrating the risk objectives criterion for a generic nuclear facility (GNF), thereby closing the loop on the application of the SHPRM. The GNF is assumed to be located at the INL site and designated as a Seismic Design Category-3 facility as per American Society of Civil Engineers (ASCE)/Structural Engineering Institute (SEI) 43-05. The demonstration includes a risk assessment for a baseline seismic hazard calculated in 2006 and an updated seismic hazard calculated in 2015. After presenting the baseline and the updated seismic hazard curves at this site, the state-of-practice methodology for calculating fragility functions for the facility is presented, along with the fragilities calculated for the GNF. Employing a fault tree analysis using the INL in-house seismic analysis and risk assessment software MASTODON, the seismic risks of collapse of the GNF for the baseline and updated seismic hazards are computed to be 5.27E−05 and 5.2E−06, respectively. The results show that not only the reevaluated seismic risk is smaller, but more importantly, that it meets the risk objectives set by ASCE/SEI 43-05.

Difficulties in explaining complex issues with maps: evaluating seismic hazard communication – the Swiss case

Abstract. A total of 2.7 billion people live in areas where earthquakes causing at least slight damage have to be expected regularly. Providing information can potentially save lives and improve the resilience of a society. Maps are an established way to illustrate natural hazards. Despite being mainly tailored to the requirements of professional users, they are often the only accessible information to help the public in deciding about mitigation measures. There is evidence that hazard maps are frequently misconceived. Visual and textual characteristics as well as the manner of presentation have been shown to influence their comprehensibility. Using a real case reflecting current practices, the material to communicate the updated seismic hazard model for Switzerland was analyzed in a representative online survey of the population (N=491) and in two workshops involving architects and engineers not specializing in seismic retrofitting (N=23). Although many best-practice recommendations have been followed, the understanding of seismic hazard information remains challenging. Whereas most participants were able to distinguish hazardous from less hazardous areas, correctly interpreting detailed results and identifying the most suitable set of information for answering a given question proved demanding. We suggest scrutinizing current natural-hazard communication strategies, empirically testing new products, and exploring alternatives to raise awareness and enhance preparedness.

Evaluation of The Seismic Hazard in The Marmara Region (Turkey) Based on Updated Databases

The increase in the wealth of information on the seismotectonic structure of the Marmara region after two devastating earthquakes (M7.6 Izmit and M7.2 Duzce events) in the year 1999 opened the way for the reassessment of the probabilistic seismic hazard in the light of new datasets. In this connection, the most recent findings and outputs of different national and international projects concerning seismicity and fault characterization in terms of geometric and kinematic properties are exploited in the present study to build an updated seismic hazard model. A revised fault segmentation model, alternative earthquake rupture models under a Poisson and renewal assumptions, as well as recently derived global and regional ground motion prediction equations (GMPEs) are put together in the present model to assess the seismic hazard in the region. Probabilistic seismic hazard assessment (PSHA) is conducted based on characteristic earthquake modelling for the fault segments capable of producing large earthquakes and smoothed seismicity modelling for the background smaller magnitude earthquake activity. The time-independent and time-dependent seismic hazard results in terms of spatial distributions of three ground-shaking intensity measures (peak ground acceleration, PGA, and 0.2 s and 1.0 s spectral accelerations (SA) on rock having 10% and 2% probabilities of exceedance in 50 years) as well as the corresponding hazard curves for selected cities are shown and compared with previous studies.

Towards Large Scale Seismic Risk Assessment in Algeria: Case Study to the City of Blida

In recent years, the use of large scale seismic risk assessment has become increasingly popular to evaluate the fragility of a specific region to an earthquake event, through the convolution of hazard, exposure and vulnerability. These studies focus on the vulnerability of the built environment of the region and the evaluation of the human social dimension, which has great importance when determining the ability of a community to attend to a disaster and to eventually resume normal activities. This study, developed within the scope of the EU-funded project ITERATE (Improved Tools for Disaster Risk Mitigation in Algeria), focuses on the development of a web-based framework for integrated seismic risk assessment in Northern Algeria, primarily focused on the city of Blida, chosen as first case-study. For this purpose, alliances with local institutions, web-based data mining techniques and specifically developed research were used to obtain: an updated seismic hazard model, and exposure and vulnerability models for local buildings and bridges, which are proposed and implemented in a web-based platform which allows the calculation of the seismic risk at a municipal level in terms of probabilistic losses. Furthermore, a social vulnerability assessment is implemented at the same level and combined with the physical vulnerability to enable the identification of the regions that are more vulnerable to earthquakes. Such framework will, in turn, empower Algerian stakeholders to perform the evaluation of earthquake scenarios at a regional scale and provide valuable information to decision makers for the implementation of risk mitigation measures in vulnerable areas.

Assessing seismic hazard of the East African Rift: a pilot study from GEM and AfricaArray

The East African Rift System is the major active tectonic feature of the Sub-Saharan Africa region. Although the seismicity level of this divergent plate boundary can be described as moderate, several damaging earthquakes have been reported in historical times, and the seismic risk is exacerbated by the high vulnerability of the local buildings and structures. Formulation and enforcement of national seismic codes is therefore an essential future risk mitigation strategy. Nonetheless, a reliable risk assessment cannot be done without the calibration of an updated seismic hazard model for the region. A major limitation affecting the assessment of seismic hazard in Sub-Saharan Africa is the lack of basic information needed to construct source and ground motion models. The historical earthquake record is sparse, with significant variation in completeness over time across different regions. The instrumental catalogue is complete down to sufficient magnitude only for a relatively short time span. In addition, mapping of seismogenically active faults is still an on-going task, and few faults in the region are sufficiently constrained as to allow them to be directly represented within the seismic hazard model. Recent studies have identified major seismogenic lineaments, but there is substantial lack of kinematic information for intermediate-to-small scale tectonic features, information that is essential for the proper calibration of earthquake recurrence models. In this study, we use new data and Global Earthquake Model (GEM) computational tools such as the Hazard Modeller’s Toolkit and the OpenQuake engine to perform a pilot study of the seismic hazard associated with the East African Rift. The hazard model obtained has been created using the most recent information available from scientific literature, global bulletins and local earthquake catalogues, including those from AfricaArray projects. In this report, in accordance with the GEM philosophy, we describe in detail all working assumptions, main processing steps, data analyses and interpretations used for the model setup.

A probabilistic seismic hazard assessment for the Turkish territory—part I: the area source model

The seismic zoning map of Turkey that is used in connection with the national seismic design code (versions issued both in 1997 and 2007) is based on a probabilistic seismic hazard assessment study conducted more than 20 years ago (Gulkan et al. in En son verilere gore hazirlanan Turkiye deprem bolgeleri haritasi, Report No: METU/EERC 93-1, 1993). In line with the efforts for the update of the seismic design code, the need aroused for an updated seismic hazard map, incorporating recent data and state-of-the-art methodologies and providing ground motion parameters required for the construction of the design spectra stipulated by the new Turkish Earthquake Design Code. Supported by AFAD (Disaster and Emergency Management Authority of Turkey), a project has been conducted for the country scale assessment of the seismic hazard by probabilistic methods. The present paper describes the probabilistic seismic hazard assessment study conducted in connection with this project, incorporating in an area source model, all recently compiled data on seismicity and active faulting, and using a set of recently developed ground motion prediction equations, for both active shallow crustal and subduction regimes, evaluated as adequately representing the ground motion characteristics in the region. The area sources delineated in the model are fully parameterized in terms of maximum magnitude, depth distribution, predominant strike and dip angles and mechanism of possible ruptures. Resulting ground motion distributions are quantified and presented for PGA and 5 % damped spectral accelerations at T = 0.2 and 1.0 s, associated with return periods of 475 and 2475 years. The full set of seismic hazard curves was also made available for the hazard computation sites. The second part of the study, which is based on a fault source and smoothed seismicity model is covered in Demircioglu et al. in Bull Earthq Eng, (2016).

A New View of the Plate Dynamics Behind Earthquakes in Ecuador

Scientists get one step closer to an updated seismic hazard map that could help Ecuador prepare for future tremors.

An updated and unified earthquake catalogue for the Western Balkan Region

The Harmonization of Seismic Hazard Maps in the Western Balkan Countries Project (BSHAP) was funded for 7 years by NATO-Science for Peace Program to support the preparation of new seismic hazard maps of the Western Balkan Region using modern scientific tools. One of the most important outputs of the BSHAP is an updated and unified BSHAP earthquake catalogue that is compiled directly from the datasets of earthquake data providers of the region. The BSHAP earthquake catalogue described here covers the geographic area limited by 38.0°–47.5°N, 12.5°–24.5°E and includes 26,118 earthquakes that occurred in the region between 510 BC and 2012. Details of data compilation efforts including the removal of duplicate events, unification of the magnitude scales, declustering of the catalogue and completeness analysis are presented in this manuscript. New magnitude conversion equations for various local magnitude scales of the data providers are developed with the aim of having homogeneous moment magnitude estimates. Completeness time intervals for the catalogue data are provided as inputs to the seismic source models used to obtain updated seismic hazard of Western Balkan Region. The unified and updated BSHAP catalogue is found to be compatible with the current well-established European and world-wide catalogues and represents a sound basis for analysis of the seismicity of this region.

Re-evaluation and updating of the seismic hazard of Lebanon

This paper presents the results of a study undertaken to evaluate the implications of the newly mapped offshore Mount Lebanon Thrust (MLT) fault system on the seismic hazard of Lebanon and the current seismic zoning and design parameters used by the local engineering community. This re-evaluation is critical, given that the MLT is located at close proximity to the major cities and economic centers of the country. The updated seismic hazard was assessed using probabilistic methods of analysis. The potential sources of seismic activities that affect Lebanon were integrated along with any/all newly established characteristics within an updated database which includes the newly mapped fault system. The earthquake recurrence relationships of these sources were developed from instrumental seismology data, historical records, and earlier studies undertaken to evaluate the seismic hazard of neighboring countries. Maps of peak ground acceleration contours, based on 10 % probability of exceedance in 50 years (as per Uniform Building Code (UBC) 1997), as well as 0.2 and 1 s peak spectral acceleration contours, based on 2 % probability of exceedance in 50 years (as per International Building Code (IBC) 2012), were also developed. Finally, spectral charts for the main coastal cities of Beirut, Tripoli, Jounieh, Byblos, Saida, and Tyre are provided for use by designers.

Seismic risk assessment and hazard mapping in Nepal

Seismic risk in the form of impending disaster has been seen from past records that moderate-to-large earthquakes have caused the loss of life and property in all parts of Nepal. Despite the availability of new data, and methodological improvements, the available seismic hazard map of Nepal is about two decades old. So an updated seismic hazard model at the country level is imperative and logical. The seismic hazard and risk model constitute important tools for framing public policies toward land-use planning, building regulations, insurance, and emergency preparedness. In fact, the reliable estimation of seismic hazard and risk eventually minimizes social and economic disruption caused by earthquakes. In this frame of reference, the seismic risk assessment at a country level is elementary in reducing potential losses stemming from future earthquakes. Thus, this study investigates structural vulnerability, seismic risk, and the resulting possible economic losses owing to future earthquakes in Nepal. To this end, seismic risk assessment in Nepal is done using an existing probabilistic seismic hazard, a newly developed structural vulnerability, and recently released exposure data. The OpenQuake-engine, the open-source platform for seismic hazard and risk assessment from the Global Earthquake Model initiative, was used to calculate the seismic hazard and risk in Nepal. The seismic hazard and mean economic loss map were formulated for the 1, 2, 5, and 10 % probability of exceedance in 50 years. Finally, the distribution of building damage and corresponding economic losses due to the recurrence of the historical 1934 earthquake was presented in this study.

Updated seismic hazard assessment of Tunisia

Modern earthquake loss models make use of earthquake catalogs relevant to the seismic hazard assessment upon seismicity and seismotectonic analysis. The main objective of this paper is to investigate a recently compiled catalog (National Institute of Meteorology or INM catalog: 412-2011) and to generate seismic hazard maps through classical probabilistic seismic hazard assessment (PSHA) and smoothed-gridded seismicity models for Tunisia. It is now established with the local earthquake bulletin that the recent seismicity of Tunisia is sparse and moderate. Therefore, efforts must be undertaken to elaborate a robust hazard analysis for risk assessment and seismic design purposes. These recommendations follow the recently published reports by the World Bank that describe the seismic risk in Tunis City as being beyond a tolerable level with an MSK intensity level of VII. Some attempts were made during the past two decades to assess the seismic hazard for Tunisia and they have mostly failed to properly investigate the historical and instrumental seismicity catalog. This limitation also exists for the key aspect of epistemic and random uncertainties impact on the final seismic hazard assessment. This study also investigates new ground motion prediction equations suitable for use in Tunisia. The methodology applied herein uses, for the first time in PSHA of Tunisia, seismicity parameters integrated in logic tree framework to capture epistemic uncertainties through three different seismic source models. It also makes use of the recently released version of OpenQuake engine; an open-source tool for seismic hazard and risk assessment developed in the framework of the Global Earthquake Model.

Probabilistic Seismic Hazard Assessment of India

Online material : Data files for seismogenic source zones (polygons), smoothed-gridded seismicity models, and hazard curves at 0.2° regular grid spacing over the study region. Earthquake disasters occur mainly due to the collapse of buildings and structures triggered by ground motions. It is, therefore, important to predict ground-shaking levels in order to determine appropriate building code provisions for earthquake-resistant design of structures. This involves extensive analyses and development of appropriate seismological models; namely, seismogenic sources, seismic site conditions, and ground motion predictions. The hazard products, viz . data and maps, constitute important tools for framing public policies toward land-use planning, building regulations, insurance, and emergency preparedness. View this table: Table 1 Major Earthquake Casualties during 1900–2008 in India and Adjoining Regions In India, several events during the last 100 years, as listed in Table 1, indicate that even moderate earthquakes ( MW < 7.0) can cause significant devastation. On one hand, ongoing urbanization and unprecedented population growth have considerably aggravated the prevailing seismic risk. On the other hand, the available seismic hazard maps covering the entire country are about a decade old. Consequently an updated seismic hazard model for the country is imperative and necessitated by new data, recent findings, and methodological improvements. In the present study, we make a case for new probabilistic seismic hazard analysis (PSHA) of India. The fundamental studies have been carried out to deliver the hazard components, including seismogenic source zonation and seismicity modeling in the Indian subcontinent (Thingbaijam and Nath 2011), assessment of site conditions across the country (Nath, Thingbaijam, Adhikari et al. 2011), and a suitability test for the ground-motion prediction equations in the regional context (Nath and Thingbaijam 2011). These components are integrated to deliver a preliminary model consisting of spatial distributions of peak ground acceleration (PGA) and 5%-damped pseudo spectral acceleration (PSA). Initial attempts at …

Effects of Seismicity Models and New Ground-Motion Prediction Equations on Seismic Hazard Assessment for Four Canadian Cities

Seismicityratesandground-motionpredictionequations(GMPEs)arethe key uncertainties in probabilistic seismic hazard analysis (PSHA). We explore the impact of new findings and knowledge from seismological and ground-motion studies on seismic hazard assessment for eastern and western Canada. Updated information includes the reevaluation of seismicity rates and their interpretation in terms of seismic source zones and the use of new GMPEs. We refer to our model as an interim updated seismic hazard model, as it does not treat all uncertainties comprehensively; rather, we address the impact of key uncertainties. Based on our updated interim seismic hazard model, uniform hazard spectra (UHS) at four major cities across Canada are obtained and compared with UHS in the current seismic hazard maps of Canada (2005/2010), whicharebasedona1995seismichazardmodeldevelopedbytheGeologicalSurveyof Canada. Sensitivity analysis highlights the significant impact of seismicity smoothing in low-to-moderate seismic regions (eastern Canada), while GMPEs are important for all regions. Moreover, our interim updated seismic hazard model can readily produce seismic hazard curves as well as seismic hazard deaggregation results for various site conditionsandformultipleprobabilitylevels;thiscapabilityisessentialforcarryingout advanced earthquake engineering analyses.

Probabilistic Liquefaction Hazard Analysis for Four Canadian Cities

Changes to building codes in the last decade, lowering the probability at which design ground motions for geotechnical applications are defined, have led to an urgent need for a probabilistic approach/tool for liquefaction potential assessment. We propose a consistent approach for probabilistic liquefaction hazard analysis (PLHA) that is based on probabilistic seismic hazard analysis and incorporates a reliability- based liquefaction potential evaluation method based on shear-wave velocity data. The method directly takes the joint probability distribution of peak ground accelera- tion and moment magnitude into account. We demonstrate the method for four Canadian cities, employing our interim updated seismic hazard models for eastern and western Canada. Using the developed method and representative site profiles, PLHA is implemented for four major cities across Canada with the aim of investigating the impact of regional seismic characteristics on liquefaction hazard assessment. Sensitivity analysis indicates that different magnitude ranges of dominant contributing seismic events have significant impact on the extent of liquefaction hazard. More specifically, for a given seismic excitation level, the relatively high hazard contribu- tions from small-to-moderate earthquakes in eastern Canada leads to less significant liquefaction potential, in comparison with similar sites in western Canada.

Seismic loss estimation of wood-frame houses in south-western British Columbia

This study extends a seismic loss model of Goda and Hong for multiple buildings by incorporating an updated seismic hazard model for western Canada, a spatial correlation model of seismic effects for subduction earthquakes, and probabilistic models of the maximum inter-story drift ratio of wood-frame houses with different shear-wall configurations, and applies to 1415 existing wood-frame houses in south-western British Columbia. The extended model is likely to produce more realistic and accurate seismic loss estimates. A series of sensitivity analyses is carried out to identify the most influential model components and to provide a range of seismic loss estimates that are based on different but valid assumptions/models. The analysis results highlight the significance of using the updated seismic hazard model. For the upper tail of probability distribution of aggregate seismic loss, the selection of an adequate spatial correlation model is of great importance. Another key model component is the determination of the ultimate seismic capacity, which inevitably involves uncertainty and judgment. These results are useful for directing efforts in future studies to improve the model.