Probabilistic Seismic Hazard Maps Research Articles

Developing design response spectra for Benghazi city including soil magnification effects

Earthquakes in some countries worldwide cause loss of lives and properties. In Libya, design of structures to resist earthquake forces was based on a paper work published by Mallick in 1976. In 1977, and after small changes in the earthquake zoning map of Libya, the ministry of housing, at that time, adopted it as a draft code of practice for the design of structures to resist earthquake forces. With Benghazi city undergoing significant rehabilitation and development programs, including major national projects, there is a pressing need to estimate updated probabilistic seismic hazard maps and design response spectra specific to the city. This study presented updated probabilistic seismic hazard ground motion for Benghazi city, considering different return periods and accounting for peak ground acceleration (PGA) values with various soil conditions. Proposed design response spectra for Benghazi City unveils substantial PGA amplifications in soft soil areas.

Probabilistic seismic hazard maps and uniform hazard spectra with site effect integration for northern of Algiers

Probabilistic seismic hazard maps and uniform hazard spectra with site effect integration for northern of Algiers

Empirical Fragility Analysis of Haitian Reinforced Concrete and Masonry Buildings

This study develops empirical fragility curves for concrete and masonry buildings in Haiti, utilizing data from the 2021 earthquake. A dataset of 3527 buildings from the StEER database, encompassing a diverse range of building types, is used. These buildings types include reinforced concrete structures with masonry infills, confined masonry buildings, reinforced masonry bearing walls, and unreinforced masonry bearing walls. Shakemaps from the USGS are utilized to assess the earthquake’s intensity at each building, with the peak ground acceleration (PGA) as the intensity measure. Damage is classified into five distinct states: no damage, minor, moderate, severe, and partial or total collapse. For each of these states, the corresponding probabilities of exceedance are calculated, and log-normal cumulative distribution functions were fitted to those data to produce empirical fragility curves. The results show a notable similarity in performance among the four types, each having high probability of failure even under low-intensity earthquakes. Total fragility curves (including all four building types) are developed subsequently and they are convolved to the probabilistic seismic hazard map of Haiti to assess the seismic risk. This includes estimating the annual probability of partial/total collapse and the probability of partial/total collapse in the event of 475-year and 2475-year earthquakes. The results indicate a significant risk, with up to 64% probability of collapse in certain areas for the 2475-year earthquake and a probability of collapse of 15% for a 475-year earthquake. These findings underscore the critical vulnerability of Haiti’s buildings to seismic events and the urgent need for their retrofit.

Macroseismic intensity attenuation models calibrated in Mw for Italy

This study aims at developing new macroseismic intensity attenuation models valid for Italy by exploiting the most updated macroseismic dataset and earthquakes catalogue, as well as the information obtained from a critical analysis of the most recent models in the literature. Several different attenuation models have been calibrated as a function of the moment magnitude (Mw) and epicentral distance from 16,260 intensity data points, that are related to 119 earthquakes occurred after 1900. According to trends and residuals analysis, the preferred calibrated intensity attenuation function is a Log-Linear model for epicentral distance (Repi in km) and a linear model for Mw as:IMCS=1.81-2.61LogR-0.0039R+1.42Mw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$I\\left( {MCS} \\right) = {1}.{81} - {2}.{61}LogR - 0.00{39}R + {1}.{42}Mw$$\\end{document}with pseudo hypocentral distance R=Repi2+9.872\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R = \\sqrt {R_{epi}^{2} + \\left( {9.87} \\right)^{2} }$$\\end{document}; the estimated standard deviation is σ = 0.75. Also noteworthy is another model for macroseismic intensity attenuation that proved to be as good as the best model and shows higher sensitivity to physical parameters, such as focal depth and magnitude, especially in the epicentral area. Performance of all calibrated models was also checked on an independent set of 15 post-1900 Italian earthquakes. One of the results of the present work is the opportunity to define earthquake scenarios (e.g. probabilistic seismic hazard maps) in terms of Macroseismic Intensity and its related standard deviation, avoiding the uncertainties due to the conversion of various ground shaking parameters into intensity values.

Seismic Risk Assessment of Typical Reinforced Concrete Frame School Buildings in Sri Lanka

The assessment of seismic risk for critical and strategic structures like schools and hospitals remains crucial, even in regions with low seismic activity. Presently, operational school buildings in Sri Lanka are primarily designed to handle gravitational loads without considering capacity-based design principles. Consequently, these structures may lack the necessary lateral resistance to mitigate potential damage or collapse during future earthquakes in Sri Lanka. Hence, conducting seismic risk assessments for such school buildings is imperative to ensure the safety of their occupants. In this research paper, we utilize a recently developed probabilistic seismic hazard map for Sri Lanka to evaluate seismic risk. We employ two nonlinear 3-D finite element models of school buildings created in OpenSees. Incremental Dynamic Analysis is conducted using a well-established set of ground motions, continuing until the structure approaches the point of collapse, to determine the probability of collapse prevention. Subsequently, we develop fragility functions for two limit states, immediate occupancy, and collapse prevention. These fragility curves are then used to compute the probability of exceeding these limit states, aiding in the assessment of the structural safety of the school buildings. A key outcome of this analysis reveals a general trend of increased damage probabilities as the number of stories in the buildings increases despite the distinct structural characteristics of each building. It is also important to note that the disparities between the immediate occupancy and more severe damage cases, such as collapse prevention, are notably pronounced in both two- and three-story school buildings.

Shear-wave velocity model of reference site conditions in South Carolina for site response analysis and probabilistic seismic hazard mapping

This paper presents the development of a shear-wave velocity (VS) model of reference site conditions in South Carolina for site response analysis and seismic hazard mapping. Model development involves creating contour maps of two geologic surfaces in the Coastal Plain with high contrasts in VS and combining the results with median VS profiles that extend to hard rock (VS ≥ 3000 m/s). Uncertainties associated with the contour maps of depth are captured in maps of the standard prediction error. Values of time-averaged VS in the top 30 m (VS,30) ranging from 1183 to 1538 m/s and 354 to 385 m/s characterize the reference site conditions in the Blue Ridge and Piedmont regions and the Coastal Plain region, respectively. The model is divided into 14 zones to facilitate site response analysis and to avoid over-smoothing resonances due to the impedance contrasts. This study is part of a larger effort to develop statewide probabilistic seismic hazard maps for the South Carolina Department of Transportation.

A novel approach to probabilistic seismic landslide hazard mapping using Monte Carlo simulations

As a potential destructive secondary hazard initiated by earthquakes, earthquake-triggered landslides can cause significant losses. Seismic landslide hazard maps are important for land use planning and landslide hazard reduction in tectonically active areas. A comprehensive probabilistic seismic landslide hazard mapping approach incorporating the uncertainties of slope properties and displacement prediction is required to promote the application of hazard maps. Based on the definition of the critical slope angle, this paper proposes an alternative seismic landslide hazard category considering the uncertainty of geotechnical properties of soil using Monte Carlo simulations and incorporating the ground motion variability based on the displacement hazard curve. The proposed new hazard category is applied to the region of Anchorage, Alaska, for the seismic landslide hazard mapping process. Subsequently, parameter analyses are performed to explore the sensitivity among the factors that contributed to the seismic landslide hazard map. The results of seismic landslide hazard maps show that the area of hazardous zone of most geologic units in present study is smaller than that in the deterministic analysis. Comparing with the probabilistic method using logic tree analysis, the proposed approach using Monte Carlo simulations predicts different landslide hazardous zone due to the probabilistic distribution of geotechnical properties of soil. The predicted hazardous zone is also sensitive to the resolution of the digital elevation model and different coefficient of variation combinations.

Mathematical modelling of proton migration in Earth mantle

In the study, we address the mathematical problem of proton migration in the Earth’s mantle and suggest a prototype for exploring the Earth’s interior to map the effects of superionic proton conduction. The problem can be mathematically solved by deriving the self-consistent electromagnetic field potential U(x, t) and then reconstructing the distribution function f(x,v,t). Reducing the Vlasov-Maxwell system of equations to non-linear sh-Gordon hyperbolic and transport equations, the propagation of a non-linear wavefront within the domain and transport of the boundary conditions in the form of a non-linear wave are examined. By computing a 3D model and through Fourier-analysis, the spatial and electrical characteristics of potential U(x, t) are investigated. The numerical results are compared to the Fourier transformed quantities of the potential (V) obtained through field observations of the electric potential (Kuznetsov method). The non-stationary solutions for the forced oscillation of two-component system, and therefore, the oscillatory strengths of two types of charged particles can be usefully addressed by the proposed mathematical model. Moreover, the model, along with data analysis of the electric potential observations and probabilistic seismic hazard maps, can be used to develop an advanced seismic risk metric.

Probabilistic seismic hazard mapping of National Capital Region of India using a modified gridded seismicity model

This is the first comprehensive study for a seismic macro-zonation of the National Capital Region of India by using the probabilistic seismic hazard analysis approach. A modified gridded seismicity model is used for this purpose, in which the earthquake occurrence rates obtained using the Gutenberg-Richter's (G-R) relationships for conventional area type seismic sources are distributed non-uniformly among a grid of cells. This provides a more robust approach than the commonly used weighted sum of area sources of homogeneous seismicity and the zone-free smoothed gridded seismicity. Other distinguishing features of the present analysis include: detailed seismotectonic evaluation of the region to identify seven area type seismic sources, compilation of a comprehensive earthquake catalogue for the estimation of seismicity recurrence parameters, selection of the most appropriate ground motion prediction equation by using a database of 71 strong motion accelerograms recorded in the region, and estimation of the compatible distance parameters by associating a fictitious fault rupture plane to each grid cell with appropriate strike and dip angles. Hazards maps are prepared for the hard rock site condition in terms of the peak ground acceleration and the 5%-damping acceleration response spectrum amplitudes for several combinations of natural periods and return periods. A simple empirical approach is also developed to obtain amplification factors for modifying the uniform hazard response spectra for the rock sites to those for the soil sites with a given VS30 value. The hazard estimates from this study are found to be somewhat higher with greater site-to-site variations as compared to those from the earlier studies.

Compilation of the seismic hazard maps in Bosnia and Herzegovina

Bosnia and Herzegovina is located in the center of the Western Balkans. Until 2018 Bosnia and Herzegovina used the hazard maps based on the macroseismic intensity. The first generation of probabilistic seismic hazard maps of Bosnia and Herzegovina is compiled and presented. Two seismotectonic models were created, the areal and linear (fault) together with the earthquake catalogue filtered out from foreshock and aftershock events. Hazard maps were constructed in terms of the peak ground acceleration, and presented in two maps, with an exceedance on average once in 95 or 475 years. The hazard map used for the design of earthquake-resistant buildings (return period of 475 years with a probability of exceedance of 10% in 50 years) is created for the ground type A with the velocity of the seismic wave propagations of vs,30 = 800 m/s. These maps have been accepted as a part of the National Annex in BAS EN 1998–1:2018.

An improved probabilistic seismic hazard mapping of peninsular shield region of India

This paper attempts to present improved probabilistic seismic hazard maps of the peninsular shield of India based on data driven seismicity and ground motion models. Combination of nine conventional area sources described by Gutenberg and Richter's (G-R) recurrence relationship and a vast tectonic province of southern peninsular shield described by a zone-free kernel smoothing approach has been used independently. Similar to that for the conventional area sources, the expected occurrence rates of earthquakes in different magnitude bins are estimated from the G-R relationships, but distributed non-uniformly among a grid of square cells in accordance with the smoothed epicentral density of the observed past seismicity. On the other hand, the occurrence rates for the tectonic province source are obtained directly by kernel smoothing of the gridded past seismicity. Other distinguishing features of the present study are (a) the use of a very comprehensive and thoroughly scrutinized earthquake catalogue, (b) data driven selection of ground motion prediction equations (GMPEs) using the limited accelerogram records available, (c) estimation of the source-to-site distances by accounting for the effects of the regional strike and dip angles of the fault rupture planes for a perfect compatibility with the distances involved in the selected GMPEs, and (d) permitting the rupture length to extend beyond the zone boundaries in the estimation of the source-to-site distances, which along with the non-uniform distribution of seismicity is able to normalize to some extent the effect of any uncertainty in deciding the zone boundaries. As the geometries of the area sources are decided mainly on the basis of the major tectonic features in the region, the hazard maps obtained are seen to depict the desired conformity with them fairly well. Also, due to the use of the data-driven selection of the highest ranking GMPEs, the hazard maps obtained are expected to be representative of the peninsular region. The rock site uniform hazard spectra for 14 important sites in different parts of the peninsular India as obtained from the presented hazard maps are compared with the corresponding design spectra based on the ASCE/SEI 7–10 and BIS codal provisions, and necessary modifications are proposed in the ASCE provisions in order to get the design spectra specific to the peninsular India. The paper also proposes empirical amplification factors to obtain uniform hazard spectra for a given VS30 value from the computed rock site uniform hazard spectra.

Site-specific probabilistic seismic hazard assessment for proposed smart city, Warangal

In the present work, a probabilistic seismic hazard analysis has been performed for the newly formed Warangal Urban District, Telangana, India. The standard Cornell–McGuire method has been adopted considering different seismic zones. The area of influence chosen is having a radius of 500 km with NIT Warangal as the centre. An earthquake catalogue for the period 1800–2016 AD has been compiled and homogenized using global empirical relationships. Alternative models have been considered for seismic zoning scenario, completeness analysis of earthquake catalogue, maximum magnitude and ground-motion prediction equations (GMPEs) in the logic tree approach by assigning normalized weighs to each model, thereby reducing the epistemic uncertainty. Seismic hazard has been presented as the peak ground acceleration (PGA) and pseudo-spectral acceleration (PSA) maps at 5% damping for spectral periods T = 0.05, 0.1, 0.5 and 1 s at 2% and 10% probability of exceedance in 50 yrs period. The results obtained were compared with IS: 1893-1 (2016) (Criteria for earthquake resistance design of structures, Part-I. Bureau of Indian Standard, New Delhi, 2016) and NDMA (2011) (Development of probabilistic seismic hazard map of India, Technical Report of the Working Committee of Experts (WCE), National Disaster Management Authority (NDMA). Govt. of India, New Delhi, 2011) and they were found to be in excellent agreement. The profile of shear wave velocity (VS) was obtained by using the multichannel analysis of surface wave (MASW) method. The site was characterized as per NEHRP manual based on VS. The obtained shear wave velocity values are used in performing the 1-D ground response. A higher PGA has been observed at surface level when compared with the PGA values obtained at rock level suggesting seismic wave amplification due to subsoil condition.

Correction to: A probabilistic seismic hazard map for the metropolitan France

Figure 20 of Drouet et al. (2020) shows the mean PGA at 475 years of return period instead of the median PGA at 475 years of return period as written in the figure caption.

Seismicity and Seismic Hazard Assessment for the Magadan region on a Scale Close to Detailed Seismic Zoning

This paper presents the results of a seismic hazard assessment for the Magadan region (quadrangle 58.5°–66.0° N, 143.3°–157.7° E) in terms of macroseismic scale units. The extent of the research corresponds to the regional one (in the terminology framework accepted in Russia, this corresponds to the scale of the detailed seismic zoning (DSZ)). The seismic activity matrix (A3.3) is obtained and the following main seismicity parameters are estimated: the slope of the recurrence graph, the average thickness of the seismoactive layer, and depth of this layer (h); on the basis of the obtained results, when constructing seismic intensity maps, the focal depth we used was h = 10 km. Proceeding from the analysis of comprehensive seismological, tectonic, and geological data, 13 zones of possible earthquake sources (PES zones) with Mmax = 6.5, 7.0 and 7.5 were distinguished in the Magadan region . Beyond the identified zones, the background seismicity was assumed to be Mmax = 5.0. The study resulted in obtaining probabilistic seismic hazard maps of the Magadan region in terms of macroseismic scale intensity units, calculated for average recurrence periods of 500, 1000, and 5000 years.

Seismic hazard curves for Warangal city in Peninsular India

A site-specific probabilistic seismic hazard analysis (PSHA) has been carried out for the heritage city Warangal in Telangana state of Peninsular India. The Cornell–McGuire approach of PSHA has been considered to estimate the hazard. The area of influence is taken as 500 km radius. A homogeneous and updated earthquake catalogue was compiled for the considered area which was later categorized into four seismic sources (zones) considering the earthquake epicentre and geology. The seismic parameters a and b were estimated and the b value of the for the four seismic zones ranges from 0.72 to 0.97, whereas the a value ranges from 2.45 to 3.20. The results obtained are shown as uniform hazard curves and hazard maps showing the spatial variation peak ground acceleration (PGA) considering 2% and 10% probability of exceedance in 50 years. The PGA and PSA values were compared with NDMA (Development of probabilistic seismic hazard map of India, technical report of the Working Committee of Experts (WCE), National Disaster Management Authority (NDMA), Govt. of India, New Delhi, 2010) and IS 1893-1 (Criteria for earthquake resistant design of structures, part 1: general provisions and buildings, 6th edition, Bureau of Indian Standards, New Delhi, 2016). The study focussed on understanding the possibility of seismic hazard at the heritage city Warangal in Peninsular India.

Probabilistic seismic hazard assessment for Hanoi city

In this study, the methodology of probabilistic seismic hazard assessment proposed by Cornell and Esteva in 1968 was applied for Hanoi city, using an earthquake catalog updated until 2018 and a comprehensive seismotectonic model of the territory of Vietnam and adjacent sea areas. Statistical methods were applied for declustering the earthquake catalog, then the maximum likelihood method was used to estimate the parameters of the Gutenberg–Richter Law and the maximum magnitude for each seismic source zone. Two GMPEs proposed by Campbell & Bozorgnia (2008) and Akkar et al., (2014) were selected for use in hazard analysis. Results of PSHA for Hanoi city are presented in the form of probabilistic seismic hazard maps, depicting peak horizontal ground acceleration (PGA) as well as 5-hertz (0.2 sec period) and 1-hertz (1.0 sec. period) spectral accelerations (SA) with 5-percent damping on a uniform firm rock site condition, with 10%, 5%, 2% and 0,5% probability of exceedance in 50 years, corresponding to return times of 475; 975; 2,475 and 9,975 years, respectively. The results of PSHA show that, for the whole territory of Hanoi city, for all four return periods, the predicted PGA values correspond to the intensity of VII to IX degrees according to the MSK-64 scale. As for the SA maps, for all four return periods, the predicted SA values at 1.0 s period correspond to the intensity of VI to VII, while the predicted SA values at 0.2 s period correspond to the intensity of VIII to X according to the MSK-64 scale. This is the last updated version of the probabilistic seismic hazard maps of Hanoi city. The 2019 probabilistic seismic hazard maps of Hanoi city display earthquake ground motions for various probability levels and can be applied in seismic provisions of building codes, insurance rate structures, risk assessments, and other public policy.

Ensemble Smoothed Seismicity Models for the New Italian Probabilistic Seismic Hazard Map

Ensemble Smoothed Seismicity Models for the New Italian Probabilistic Seismic Hazard Map

Evolution of seismic hazard maps in Turkey

A review on the historical evolution of seismic hazard maps in Turkey is followed by summarizing the important aspects of the updated national probabilistic seismic hazard maps. Comparisons with the predecessor probabilistic seismic hazard maps as well as the implications on the national design codes conclude the paper.

Ground-motion characterization for the probabilistic seismic hazard assessment in Turkey

This study describes the methodology implemented to establish the ground-motion logic-tree for national probabilistic seismic hazard map of Turkey for shallow active crustal regions. The presented procedure provides quantitative information to guide the hazard experts while establishing the logic tree to capture the epistemic uncertainty in ground-motion characterization. It uses non-data-driven and data-driven testing methods to identify and rank candidate ground-motion prediction equations (GMPEs) under a specific ground-motion database. The candidate GMPEs are subjected to visual inspection and are classified into center, body and range (CBR) spectral estimates for a proper consideration of epistemic uncertainty. The GMPEs classified into CBR are then used in a suite of seismic hazard sensitivity analysis to establish the most suitable GMPE logic-tree whose spectral estimates are not biased by any one of the GMPEs in the logic-tree structure. The sensitivity analysis considers normalized spectral ordinates and is not manipulated by the spectral amplitudes. The proposed procedure is inherited from the relevant studies of the Earthquake Model of the Middle East (EMME; www.efehr.org:8080/jetspeed/portal/emme.psml) regional seismic hazard project. This paper also highlights the similarities and differences in ground-motion characterization between EMME and our approach.

Updates to the Seismic Activity Models of Japan: Lessons from the Great Tohoku Earthquake

ABSTRACT The 11 March 2011 Tohoku earthquake was the largest seismic event in the history of Japan. Potential mega‐earthquakes were not included in the National Seismic‐Hazard Maps for Japan (NSHMJ) because of the lack of information regarding very infrequent disastrous earthquakes that had occurred before no historical earthquakes were recorded. These earthquakes were not included in the conventional seismic activity model used to assess the probabilistic seismic‐hazard maps (PSHM); however, we recognize that it is essential for the probabilistic seismic‐hazard assessment to consider earthquakes that have a very low probability of occurrence. In order to improve the PSHM, we reconstructed the seismic activity model by (1) revising the long‐term evaluation of magnitude and occurrence probability for large earthquakes; (2) resetting the maximum magnitude of background earthquakes; (3) introducing large area sources to model the background seismicity model for crustal earthquakes; (4) modeling outer‐rise earthquakes; (5) revising the model for large earthquakes in the eastern margin of the Japan sea; and (6) developing new earthquake models for major active faults. Applying these improvements, the revised version of the NSHMJ was published in December 2014 by the Earthquake Research Committee of Japan.