Probabilistic Seismic Hazard Analysis Research Articles

Study of Earthquake Hazard Probability Based on PGA (Peak Ground Acceleration) Using the PSHA Method in Semarang Regency, Indonesia

Semarang Regency was one of the areas affected by the earthquake. This happens because it is located north of the subduction zone and has active faults, so research is needed to identify the impact of earthquakes in Semarang Regency as an initial action in disaster mitigation efforts. This research aims to determine the distribution of PGA values in the Semarang Regency area and to assess the seismic hazard due to earthquakes based on a map of the distribution of PGA values in the Semarang Regency area. The method used is the Probabilistic Seismic Hazard Analysis (PSHA) method, which uses earthquake catalogues from BMKG, USGS, IRIS, and ISC. The earthquake source data was the n processed using ZMAP and R-CRISIS software. The results of seismic hazard analysis in the Semarang Regency area for a probability of exceeding 10% in 50 years or an earthquake return period of 475 years in bedrock with a period of 0 seconds obtained a PGA value ranging from 0.368–0.844 g, for a short period of 0.2 seconds the PGA value obtained ranged from 0.647. –1.773 g, for 1 second, the PGA value obtained ranges from 0.320–0.852 g. The highest PGA value is in West Ungaran District, with a value of 0.844 g. The lowest PGA value is in Kaliwungu District, which has a value of 0.458 g. The active fault zones influence the danger of earthquakes in the Semarang Regency area in Semarang Regency.

Development of a regionally consistent and fully probabilistic earthquake risk model for Central Asia

Abstract. A fully probabilistic earthquake risk model was developed for five countries in Central Asia, providing updated earthquake loss estimates with a higher level of detail on all components with respect to previous studies in the region. Additionally, a regionally consistent approach that, on the one hand, allows for direct comparisons at different disaggregation levels (e.g., country and oblast) was used. On the other hand, this updated earthquake risk assessment aims to facilitate initiating a policy dialogue regarding national and regional disaster risk financing and insurance applications. This earthquake risk model made use of a regional probabilistic seismic hazard analysis and a comprehensive exposure database on which different types of assets and sectors were included and for which two scenarios (the years 2020 and 2080) were modeled. For each type of asset, a unique vulnerability function was derived and later used for convolution with the hazard data, which allowed for the estimation of the loss exceedance curve, at different disaggregation levels, from where other risk metrics such as the average annual loss (AAL) and specific return period losses were obtained. The regional earthquake AAL for the five countries and for the 2020 exposure scenario has been estimated to be around USD 2 billion, with the Kyrgyz Republic and Tajikistan being the countries with the highest earthquake risk levels in the region. Besides the probabilistic earthquake risk results, as-if scenarios were modeled using a pseudo-deterministic approach to assess the human and economic losses for realistic and representative earthquakes for the main cities within earthquake-prone regions in the five countries of the study area.

The maximum magnitude of natural and induced earthquakes

A key element in the assessment of seismic hazard is estimation of the maximum possible earthquake magnitude, Mmax. A great deal of effort has been invested in developing approaches to estimate Mmax for natural (tectonic) earthquakes, especially in regions of relatively low seismicity where it is difficult to associate observed seismicity with known geological faults. In probabilistic seismic hazard analysis, there has been a tendency to assign a narrow range of large values to Mmax. This results in the impression that hazard results are insensitive to this parameter, which is not the case when the Mmax distribution captures the full range of possible values. For induced seismicity, Mmax estimates can have far-reaching implications both in terms of quantitative assessments of the resulting seismic hazard and risk, and in terms of the public and regulatory perception of this risk. Estimates of Mmax for induced seismicity need to distinguish between driven earthquakes, for which magnitudes are largely controlled by operational parameters, and triggered tectonic earthquakes, together with estimates of the likelihood of such triggering. Distributions of triggered Mmax may be limited to smaller magnitudes than distributions for natural seismicity due to the shallow depth of most injection/extraction wells. For the management of induced seismic risk, the expected largest event magnitude (which may be influenced by a Traffic Light Scheme in operation) may be more relevant than any physical upper bound truncating the recurrence relationship.

A Methodologic Approach to Study Large and Complex Landslides: An Application in Central Apennines

The evaluation of landslide hazards in seismic areas is based on a deterministic analysis, which is unable to account for various uncertainties in the analysis process. This paper focuses on the probabilistic local seismic hazard analysis and extends the results to the landslide hazard analysis to consider both the uncertainties of the ground deformations and the strengths. The work studies the areas between Nibbiano and Sant’Erasmo hamlets in the Camerino municipality located in central Italy, where all constructions present evidence of damage caused by both the seismic sequence of 2016–2017 and the slope instability. An exhaustive geological and geophysical investigation has clarified the geological, geomorphological, and hydrogeological characteristics of the area, enabling a new characterization of material stress-strain behaviour. The study reveals that the low stiffness of the debris covers, and their fair degree of permeability contribute to potential instability scenarios triggered by both intense rainfall and the effects of strong earthquakes. The goal was to utilize the results to support local urban planning because in-depth knowledge of the possible evolutionary scenarios of the slopes is fundamental to the management of the degree of danger for structures, especially for people. Moreover, it was shown once again how a multi-source approach, with different investigation techniques, cannot be ignored for the study of the evolution of complex landslides.

Hazard zonation for potential earthquake-induced landslide in the eastern East Kunlun fault zone

Abstract Based on probabilistic seismic hazard analysis, the seismic landslide hazard research considers the spatial and temporal distribution characteristics of seismic peak ground acceleration, which integrates the factors such as seismic intensity, location, and recurrence time. The occurrence of future earthquakes has certain randomness. This article presents the landslide hazard zoning of the eastern Kunlun fault zone and its surrounding faults, which is carried out under the action of horizontal ground motion with certain exceeding probability. According to the geological structure and seismicity characteristics of the study area, the potential source is divided. Based on the seismic hazard analysis and Newmark cumulative displacement evaluation model, the seismic landslide hazard in the study area is analyzed. The landslide probability is taken as the risk index. The seismic landslide hazard can be divided into five grades: extremely low-prone area, low-prone area, medium-prone area, high-prone area, and extremely high-prone area. In the results of seismic landslide risk zoning given in this article, the surrounding areas of Tazang fault and Minjiang fault are high-risk areas, which should be paid attention to.

Creep on the Argentine Precordillera Décollement Following the 2015 Illapel, Chile, Earthquake: Implications for Andean Seismotectonics

AbstractThe Central and South‐Central Andes form a “two‐sided” mountain belt bounded by distinct zones of convergence in the forearc and backarc flanks. Previous geodetic interseismic deformation studies found that the forearc to backarc velocity field is better explained when elastic models allow reverse aseismic slip on the Andes eastern‐flank décollement faults. Here, we extend the earlier interpretation of interseismic motion and argue that normal aseismic creep of the Precordillera décollement is required to explain backarc Global Navigation Satellite System displacements during the co‐ and early postseismic phases of the 2015 Illapel, Chile, earthquake. This model significantly reduces the previously reported overlap between coseismic slip and afterslip on the megathrust of this earthquake, consistent with the expectation that these slip modes are spatially partitioned. These findings have direct implications for estimating recurrence interval and slip rate, and for probabilistic seismic hazard analysis on both sides of the orogen.

Declustering characteristics of the North China Plain seismic belt and its effect on probabilistic seismic hazard analysis

The accurate and impartial identification of background seismic activity is an important foundation for earthquake model construction and probabilistic seismic hazard analysis (PSHA). We use the Gardner and Knopoff, Reasenberg, nearest-neighbor and stochastic declustering methods to decluster in the North China Plain seismic belt, analyzing the effect of declustering. We optimize the input parameters of the algorithms through Kolmogorov-Smirnov Poisson distribution tests (e.g., the clustering threshold of the nearest-neighbor method is set to 0.6). Four algorithms demonstrate good declustering effects, removing the impact of the strong seismicity in Tangshan while retaining similar trends to all events. The occurrence of major earthquake events can significantly impact the declustering characteristics in terms of time, space and magnitude. There is a difference in the overall hazard between the four declustering algorithms and the Fifth Generation Seismic Ground Motion Parameters Zonation Map of China. The difference in seismic hazard curves is mainly influenced by the annual average occurrence rate (background rates) and the Gutenberg-Richter b value, with the effect of the b value being more pronounced. The analysis of the effect of algorithms and their impact on PSHA can provide reference for earthquake risk assessment, engineering seismic design and disaster research.

Probabilistic Seismic Hazard Assessment of Lisbon (Portugal)

The 1755 Lisbon earthquake holds significant historical importance in Portuguese history. The subsequent tsunami resulted in extensive destruction and damage, affecting not only Lisbon but also other regions of Portugal, Spain, and North Africa. This significant and hazardous event led to an increase in awareness about earthquake and tsunami risks, not only within Portugal but throughout Europe. This heightened awareness facilitated advancements in scientific developments, including design codes, standards, and earthquake engineering. However, recent studies focusing on hazard assessment for Lisbon are limited. For this reason, this paper aims to present a comprehensive probabilistic seismic hazard analysis (PSHA) for the Lisbon metropolitan area. The first stage of PSHA involves defining applicable and active seismic source models (area and line sources) within the study area. Subsequently, historical and instrumental earthquake records are collected to build a homogenized earthquake catalog, utilizing both global and local earthquake databases. Following this, the completeness level of the earthquake catalog is tested. By incorporating suitable ground motion models to the region and local soil characteristics, seismic hazard maps for various return periods and hazard curves in terms of peak ground acceleration (PGA) are developed. The findings based on the area source model agree with existing literature, indicating PGA values ranging from 0.3 g to 0.9 g, 0.2 g to 0.7 g, 0.2 g to 0.5 g, and 0.1 g to 0.3 g for return periods of 2475, 975, 475, and 50 years, respectively.

Amplification factors of intensity measures for site-specific PSHA using spectrally equivalent pulse-like and non-pulse-like ground motion records

Proper representations of ground motion characteristics and prediction of rock-to-ground amplification factors (AFs) of intensity measures (IMs) are crucial in site-specific probabilistic seismic hazard analysis (PSHA). By using spectrally equivalent pulse-like and non-pulse-like ground motion suites within the convolution-based PSHA framework, this paper aims to (i) investigate the amplification patterns and AF prediction efficiency for 16 typical IMs; and (ii) evaluate the sensitivities of AF and PSHA to the pulse-characteristic, rock-IM type, and AF functional form. The results reveal that IMs are generally amplified, whereas de-amplification occurs at soft sites for IMs largely dominated by high-frequency content (e.g., Arias intensity). Specific rock-IMs for predicting AFs are recommended through efficiency criterion. The results for pulse-like and non-pulse-like suites are found to be not significantly different; hence, including pulse-like records is generally not essential in convolution-based PSHA as long as the bedrock spectra designed with pulse-type features have been matched. Meanwhile, the similar AF predictions from the linear and nonlinear models indicate that the choice of functional form is of secondary importance. Instead, the selection of rock-IM is of higher importance, especially for soft sites and high-frequency dominated IMs. This study could provide useful insights into ground motion selection and AF prediction for site-specific PSHA.

Drivers to seismic hazard curve slope

AbstractThe slope of a linear approximation of a probabilistic seismic hazard curve, when it is represented in the log‐log scale, is a key parameter for seismic risk assessment based on closed‐form solutions, and other applications. On the other hand, it is observed that different hazard models can provide, at the same site, comparable ground shaking, yet appreciably different slopes for the same exceedance return period. Moreover, the slope at a given return period can increase or decrease from low‐ to high‐hazardous sites, depending on the models the probabilistic seismic hazard analysis (PSHA) is based on. In the study, the sensitivity of the slope to the main model components involved in PSHA was explored, that is: the earthquake rate, the magnitude and source‐to‐site distance distributions, and the value of the residual of ground motion models (GMM). With reference to a generic site, affected by an ideal seismic source zone, where magnitude follows the Gutenberg‐Richter (G‐R) relationship, it was found that the local slope of hazard curve increases with the following factors in descending order of importance: (i) increasing distance from the source; (ii) decreasing maximum magnitude and increasing ‐value of the G‐R model; (iii) increasing rate of earthquakes of interest; (iv) increasing residual of the GMM. These results help explain the systematic differences in hazard curve slopes found in three authoritative hazard models for Italy, and the related impact on simplified risk assessment.

Analisis Bahaya Bencana Gempa Bumi di Wilayah Kabupaten Pesisir Selatan

This study aims to determine the earthquake hazard levels in Pesisir Selatan Regency, West Sumatra Province, by identifying the Peak Ground Acceleration (PGA) values and the distribution of earthquake hazard levels. The type of research used is quantitative descriptive analysis and spatial analysis. The method employed in this study is Probabilistic Seismic Hazard Analysis (PSHA). To determine the Peak Ground Acceleration values, parameters such as earthquake location, occurrence time, and earthquake magnitude are used. For determining the earthquake hazard distribution, data on Ground Amplification Factor (GAF) is utilized. The results of this study show that the distribution of Peak Ground Acceleration in the study area ranges from 0.17 g to 0.93 g. The value of 0.17 g is found in Koto XI Tarusan District, while the highest value is observed in Silaut District. Additionally, the distribution of earthquake hazard levels shows that areas with low hazard level cover 697.04 km², moderate hazard level covers 4150.49 km², and high hazard level covers 1201.81 km². This study provides earthquake hazard maps that can be used for mitigation and planning in the region.

RANKING OF SEISMIC INTENSITY ATTENUATION LAWS AND MODELING OF SEISMIC SOURCES FOR SEISMIC HAZARD ASSESSMENT IN UZBEKISTAN

Quantitative assessments of seismic hazard in seismically active areas depend to a large extent on the intensity-distance attenuation laws which are used in calculations. To account for epistemic uncertainty in the nature of seismic effects, it is recommended to perform probabilistic seismic hazard analysis using several different attenuation relationships. The most effective tool for their selection is the ranking procedure which consists in attributing a weight to one or another equation depending on the degree of compliance between the equation-based seismic effects and the real experimental data available for the region under study. The article presents the results of ranking intensity attenuation laws derived for Central Asia. Ranking was carried out by LH and LLH methods. Based on the ranking results, these has been made a generalized attenuation model used subsequently in PSHA for Uzbekistan. Consideration was given to three alternative models of seismic sources: area sources, active faults, and seismogenic zones. Parameterization of the models considered involved determining seismic potential, frequency of recurrence of earthquakes of different energy levels, and the predominant type of motions in each earthquake source. Seismic zoning maps of Uzbekistan in points of the MSK-64 intensity scale have been compiled for different probabilities of occurrence of non-exceedance level earthquakes in the next 50 years.

Probabilistic seismic hazard analysis of the Coimbatore region, Tamil Nadu using a logic-tree approach

Probabilistic seismic hazard analysis of the Coimbatore region, Tamil Nadu using a logic-tree approach

Analyzing the dependency of earthquake insurance premium on the intensity measure used in probabilistic seismic hazard analysis and fragility curves

Considering the uncertainties associated with earthquake, seismic response of structures, damage caused by the response and the repair costs, determining Earthquake Insurance Premium (EIP) is a challenging task that requires a framework for modeling all inherent risks. Most of the models proposed for EIP determination have two basic components. The first component indicates the probability of seismic hazard (generally obtained from the probabilistic seismic hazard analysis), and the second component indicates the probability of occurrence of a given damage to the structure with respect to different seismic hazard levels (generally obtained from the fragility curves). These two components are interconnected through an intermediate parameter, known as the Intensity Measure (IM), which is of great importance in calculations and has hardly been considered so far. In this study, the dependency of EIP on the IM used in the probabilistic seismic hazard analysis and the fragility curves is analyzed. To this end, the EIP was determined for five types of buildings at low, medium and high seismic hazard levels using two IMs (peak ground acceleration and first mode spectral acceleration). The results of this study warn that the EIP can be highly dependent on the IM, so that for all studied structures, the EIP determined based on peak ground acceleration at a high seismic hazard level is nearly three times as many as the one determined by the first mode spectral acceleration. A significant finding is that when the first mode spectral acceleration is used as the IM, the ratio of EIP at different seismic hazard levels closely matches the ratio of IM at the same levels. This result can be valuable in developing insurance codes and regulations. However, this is not the case for the currently used IM, i.e., peak ground acceleration.

Advancing the understanding of earthquake risk in Portugal

The assessment of earthquake risk at the national scale is crucial for the design and implementation of risk reduction measures. Due to its location in the southwest of the Eurasian plate, Portugal is exposed to moderate to strong seismic events, such as the well-known 1755 Lisbon earthquake. We reviewed existing studies covering exposure, seismic hazard, vulnerability, and risk assessment for Portugal, and performed probabilistic seismic hazard and risk analyses for the country using new model components. These include a new exposure model developed for the residential building stock using the 2021 national Building Census Survey, a recent exposure model for commercial and industrial buildings, updated vulnerability functions for 116 building classes, and the recently released European Probabilistic Seismic Hazard model. The seismic risk results include average annual economic losses, fatalities, buildings with complete damage, and population left homeless. These results allowed the identification of the regions in Portugal with the highest earthquake risk, as well as which building classes contribute the most to the overall impact.

Site-Specific Seismic Hazard Analysis for Shallow Tunnel in Nepal

Abstract Several seismic codes are implemented for the design and construction of superstructures in Nepal but there is no seismic guideline for shallow tunnels which are often constructed using conventional engineering approaches. The uniform hazard spectrum was obtained after performing a Probabilistic Seismic Hazard Analysis at Dhulikhel and the target spectrum was estimated by comparing it with the spectrum recommended by the seismic code of Nepal Building Code NBC 105:2020 and Indian standard IS 1893:2016. The average response spectrum from ten recorded earthquake ground motions was selected from a peer ground motion database with the known shear wave velocity obtained from geophysical survey. The comparative analysis revealed that the design spectra for identical soil classes, as determined by this study are slightly higher than those prescribed by the present seismic code provisions. This finding emphasizes the necessity for developing more specific guidelines tailored to the design of shallow tunnels in Nepal to ensure their structural resilience in the event of an earthquake.

Amplitude and duration hazard-consistent ground-motion selection for seismic risk assessment in Mexico City

The emphasis of seismic design regulations on applying nonlinear dynamic analyses (NDAs) promotes using accelerograms that characterize site-specific ground motions. Commonly, amplitude levels of such accelerograms are defined by a target spectrum that could be based on a uniform hazard spectrum (UHS), which is determined by a probabilistic seismic hazard analysis (PSHA) and represents a response spectrum with ordinates having an equal probability of being exceeded within a given return period, Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document}. Conversely, the definition of ground-motion duration levels is not yet properly defined in current regulations to select accelerograms. Thus, adhering to data handling as that for amplitude ground-motion parameters, this study motivates executing PSHAs to define hazard-consistent levels for the ground-motion duration. That is, accelerograms can be selected to match both amplitude and duration ground-motion levels associated with Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document}. Further, fragility functions conditional on Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document} that cover typical performance objectives can be developed using sets of hazard-consistent accelerograms to implement, e.g., multiple stripe analyses (MSAs). To demonstrate the importance of choosing fully hazard-consistent accelerograms to perform NDAs, this study includes the displacement- and energy-based seismic-response evaluation of a steel frame building located at different soil-profile sites in Mexico City. Sets of fully hazard-consistent accelerograms and solely amplitude-based hazard-consistent accelerograms were artificially generated per site for values of Tr\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${T}_{r}$$\\end{document} up to 5000 years. Results indicate that the probability of failure can be underestimated if the ground-motion duration is unvaried in MSAs, e.g., structural damage caused by 50-year return-period or higher events can be more noticeable when fully hazard-consistent accelerograms take place.

Novel approach for energy-spectrum-based probabilistic seismic hazard analysis in regions with limited strong earthquake data

With the rapid development of energy-based seismic design, probabilistic seismic hazard analysis (PSHA) in terms of the input energy spectrum, E I, has become increasingly important. Generally, implementing E I-based PSHA requires a ground-motion prediction equation (GMPE) for E I. However, although a GMPE for E I can be constructed in regions with abundant earthquake data based on regression analyses, it is difficult to obtain in regions lacking strong ground-motion records. Therefore, this study proposes a new approach for performing E I-based PSHA in regions with limited earthquake data. Instead of using a GMPE for E I directly, a model of Fourier amplitude spectrum (FAS) is adopted, which can be determined using a small number of earthquake data with small-to-moderate magnitudes. Then, the E I of the ground motion is obtained from FAS based on the relationship between E I and FAS. Furthermore, to calculate the annual intensity exceedance rate within the proposed framework of adopting the FAS model, a highly efficient method, namely, the moment method, is applied. Several numerical examples indicate that the proposed approach not only is suitable for regions lacking strong ground-motion records but also performs very efficiently in calculating the annual intensity exceedance rate.

Quantifying the effect of pulse-like ground motions on the seismic design of SMA restrained isolation bridges using probabilistic repair cost method

The shape memory alloy (SMA) restrainer serves as an effective but expensive bridge restraining device. However, the impact of pulse effect on SMA design approach under pulse-like ground motions (PLGM) has not been fully quantified in previous studies, which hinders its application in near-fault regions. Therefore, based on the risk probability assessment method throughout the entire life cycle, by accounting for the comprehensive repair cost of each component damage, this paper introduces a parameter design method for SMA restrainer of near-fault bridges that considers structural parameters, pulse parameters, and economic indicators. Firstly, the repair cost ratio (RCR) of bridge system, which means the expenses for repairs expressed as a proportion of bridge replacement costs, was regarded as the life-time optimization goal and overall performance indicator. Secondly, by accounting for near-fault effects, the relationship between RCR and SMA design parameters was established by convolution algorithm of probabilistic seismic hazard analysis, demand analysis and capacity analysis. A novel probabilistic seismic demand model was utilized to quickly determine the RCR of the bridge system under PLGM. Finally, the influence of pulse period on the rational design parameter of SMA restrainer was comprehensively investigated by RCR-based method. A seismic isolation arch bridge was selected as the illustrated case in this article. The results indicate that the rational design parameters of SMA exhibit a pattern of initially rising, then falling as the pulse period increases, reaching the peak value when the pulse period approaches bridge fundamental period. Moreover, the price parameter of SMA significantly affect the optimal design parameters, and the effective range is also recommended.

Probabilistic seismic hazard analysis of Nepal considering validated seismic source model

Probabilistic seismic hazard analysis of Nepal considering validated seismic source model