Seismic Hazard Maps Research Articles

Seismic Hazard Maps of the Northwest and Central Caucasus on a Detailed Scale

The paper presents the results of a new generalization of seismic hazard data for the northwestern and central sectors of the Greater Caucasus. A fundamentally new model of the seismotectonic basis for the seismic hazard map of the region has been prepared. The model is used to calculate seismic impact on a probabilistic basis. The work included three stages. At the first stage, seismotectonic studies were carried out, as a result of which a seismotectonic model was created and a map of zones of possible earthquake centers was compiled. At the second stage, the seismicity and seismic regime were studied in detail. The third stage calculated the frequency of seismic vibrations of various intensities in the study area based on the parameters of the macroseismic field equation, seismic activity patterns, zones of possible earthquake sources, and the slope of the earthquake frequency of the earthquakes. As a result, seismic hazard maps were compiled. The northwestern and central sectors of the Greater Caucasus look like a seismic hazardous area, where the level of seismic impacts reaches 8.5 on maps A and B. At the same time, compared to the data from the GSZ-97 and GSZ-2015 maps, the results appear more differentiated and generally significantly reduce the level of seismic hazard in the region. The study is important from the methodological aspect in light of seismic risk management of this densely populated and actively developed territory of Russia.

Spatio-temporal dynamics in seismic exposure of Asian megacities: past, present and future

The estimation of urban growth in megacities is a critical and intricate task for researchers and decision-makers owing to the complexity of these urban systems. Currently, the majority of megacities are located in Asia which is one of the most disaster-prone regions in the world. The high concentrations of people, infrastructure and assets in megacities create high loss potentials for natural hazards; therefore, the forecasting of exposure metrics such as built-up area is crucial for disaster risk assessment. This study aims to identify and project the dynamics of built-up area at risk using a spatio-temporal approach considering seismic hazard in three Asian megacities, namely Jakarta, Metro Manila and Istanbul. First, Landsat Thematic Mapper images were processed to obtain the built-up areas of 1995 and 2016 for Metro Manila, and of 1995 and 2018 for Jakarta and Istanbul. The SLEUTH urban growth model, a cellular automaton (CA)-based spatial model that simulates urban growth using historical geospatial data, was then employed to predict the urban growth of these megacities by 2030. Finally, seismic hazard maps obtained for 10% and 2% probabilities of exceedance were overlaid with built-up area maps. For a seismic hazard of 10% probability of exceedance in 50 years, the total urban area subjected to Modified Mercalli intensities (MMI) VIII and IX has increased nearly 65% over 35 years in Metro Manila. For Jakarta and Istanbul, the total urban area at the MMI VIII level has increased nearly 79% and 54% over 35 years, respectively. For a seismic hazard of 2% probability of exceedance in 50 years, the total urban area subjected to MMI IX has increased nearly 75%, 65% and 49% over 35 years in Jakarta, Metro Manila and Istanbul, respectively. The results show that urban growth modelling can be utilized to assess the built-up area exposed to high risk as well as to plan urban growth considering natural hazards in megacities.

GIS-technologies in geophysical information databases processing

There are vast opportunities for obtaining a huge amount of information about various objects in modern world. This information can often be processed only using modern computer technologies. The development and implementation of the new methods for modeling the geological objects, moving or spreading a particular geophysical process, represent an important task of establishing interconnections and spatial distributions’ correlation in various physical fields. The seismic events recorded by 20 seismic stations installed in the areas with different soil conditions have been analyzed. To exclude the influence of the seismic vibrations source type, the seismic records were selected for each station, the epicenters of which were in the same area 20x20 km in size. The diagrams depicting the vibrations real spectrum acceleration area were prepared. For most of the obtained dependences, it was found that the real spectrum area of vibrations and acceleration are related in a nonlinear manner. In this case, the nonlinear dependence begins to develop, as a rule, at the acceleration values above 0.1g. From this we can conclude that the use in the construction calculations of the expected earthquake manifested intensity values is not sufficient for a reliable assessment of the possible seismic impact level, since the dependence of the incoming energy on the intensity magnitude is not linear. This implies the need to build the seismic hazard maps of the territory in the acceleration units.

A Macro Seismic Hazard Zonation for Sri Lanka

This paper describes the outcome of a comprehensive study carried out to analyse the seismic hazards affecting Sri Lanka. The main seismic threat is from oceanic earthquakes originating at failed Mannar rift zone and Comorin ridge off the west to south west coast with some secondary influence from South Indian crustal earthquakes. The analyses were performed using Deterministic Seismic Hazard Assessment, Probabilistic Seismic Hazard Assessment and seismic wave propagation using FLAC software ignoring the overburden attenuation within the landmass. The seismic scenario included 100 years earthquake catalogue with an characteristic earthquake of magnitude 6.9 at a distance 90 km from the west coast. Historical records of earthquakes in the vicinity of Sri Lanka indicate that 1615 earthquake was the most significant earthquake that affected Sri Lanka. The analyses show that South West to North West coastal areas are the most vulnerable to seismic hazards. There is also reflection of seismic waves leading to amplification of seismic waves in the central highland. Based on the analyses described above, a seismic hazard map for Sri Lanka dividing the country into two zones of seismic intensity and response spectrum is provided accordingly. The study was constrained by the lack of recorded data of past earthquake responses within the country and a network of seismic stations are proposed in the paper for future data collection.

Relationships between ground motion parameters and macroseismic intensity for Italy

The relation between macroseismic intensity and ground shaking makes it possible to transform instrumental Ground Motion Parameters (GMPs) in macroseismic intensity and vice versa, and is therefore useful for making comparisons between estimates of seismic hazard determined in terms of GMPs and macroseismic intensity, and for other engineering and seismological applications. Empirical relationships between macroseismic intensity and different recorded GMPs for the Italian territory are presented in this paper. The coefficients are calibrated using a dataset of horizontal geometrical mean GMPs, i.e. peak ground acceleration, peak ground velocity, spectral acceleration at 0.2, 0.3, 1.0 and 2.0 s from the ITalian ACcelerometric Archive (ITACA; Luzi et al. in Italian Accelerometric Archive v3.0, Istituto Nazionale di Geofisica e Vulcanologia, Dipartimento della Protezione Civile Nazionale, 2019. https://doi.org/10.13127/itaca.3.0), and macroseismic intensity at Mercalli–Cancani–Sieberg (MCS) scale from the database DBMI15 (Locati et al. in Database Macrosismico Italiano (DBMI15), versione 2.0, Istituto Nazionale di Geofisica e Vulcanologia (INGV), 2019. https://doi.org/10.13127/DBMI/DBMI15.2). A dataset is obtained that corresponds to 240 pairs of macroseismic intensity-GMPs from 67 Italian earthquakes in the time window 1972–2016 with moment magnitude ranging from 4.2 to 6.8 and macroseismic intensity in the range [2, 10–11]. The final dataset correlates strong motion stations and macroseismic intensity observations generally within 2 km from each other, and each association is manually validated through an expert judgement. The adopted functional form is non-linear, predicting macroseismic intensity as a function of LogGMPs and vice versa by performing separate regressions. The set of empirical conversion relationships GMP–IMCS–GMP and the associated standard deviations are compared with previous models. In order to verify the proposed model, a map in terms of PGA is obtained, starting from the PSHA in terms of intensities (Gomez Capera et al. in Bull Seismol Soc Am 100(4):614–1631, 2010. https://doi.org/10.1785/0120090212) and then using the empirical relationship here proposed in PGA, and compared with the National Italian seismic hazard map (Stucchi et al. in Bull Seismol Soc Am 101(4):1885–1911, 2011. https://doi.org/10.1785/0120100130).

Obtaining suitable logic-tree weights for probabilistic earthquake-induced landslide hazard analyses

In this study, an inventory of landslides induced by the 2011 Lorca earthquake (Mw 5.1) has been used in order to develop a new procedure to obtain objective logic-tree weights for a probabilistic earthquake-induced landslide hazard analysis. The 2011 Lorca earthquake triggered more than 250 landslides, mainly of disrupted type. The logic-tree was designed having regard to variability of relevant geotechnical parameters involved in the problem and uncertainties associated with the use of several empirical relationships in order to compute Newmark displacements. For the purpose, the resulting hazard maps were compared with this landslide inventory, and weights estimated for each branch of the logic tree based on these results. The best model for seismic landslide hazard mapping for a moderate earthquake correctly identifies around 72% of landslide areas. Based on the set of parameters that comprises (depth of failure surface, specific weight, cohesion, friction angle and Newmark displacement model), the corresponding weights were objectively established. These weights are reliable enough for the obtaining seismic landslide hazard maps and may be implemented in similar environments characterized by moderate-low magnitude earthquakes (Mw < 5.5).

Comparative PGA-driven probabilistic seismic hazard assessment (PSHA) of Turkey with a Bayesian perspective

While there has been significant research on probabilistic seismic hazard analysis (PSHA) using several different seismic sources, this paper focuses particularly on understanding the spatially varying seismic hazard controlled only by earthquakes. In that vein, regarding Turkish seismicity, this study is the first of its kind to explore this conundrum from a Bayesian point of view and offer new estimates to compare with the existing ones. In this study, a national-extent peak ground acceleration (PGA)–driven hazard map (upon 90% quantile of maxima, VS30 = 760 m/s, and a return period of 475 years) was created and then compared both with the old and new versions of the officially recognized seismic hazard maps of Turkey. Regarding 10 earthquake-prone cities, the new PGA estimates were compared with those picked from these two maps. Next, individual site-based hazard estimates were drawn for these city centers considering the return periods of 43, 72, 140, and 475 years. The present hazard map was in compliance with the seismotectonic setup of Turkey and its PGA estimates were slightly high compared with the last two hazard maps for some specific regions, most of which are located in major active fault zones with a history of intense seismic activity, albeit the figures for low seismic zones were relatively low. With this study, it becomes clear that the process of PSHA, which innately requires a long and tiresome effort, can instantaneously be performed against the changing of catalog data over time, and thence prompt evaluations on variations can consequently be made.

California Historical Intensity Mapping Project (CHIMP): A Consistently Reinterpreted Dataset of Seismic Intensities for the Past 162 Yr and Implications for Seismic Hazard Maps

AbstractHistorical seismic intensity data are useful for myriad reasons, including assessment of the performance of probabilistic seismic hazard assessment (PSHA) models and corresponding hazard maps by comparing their predictions to a dataset of historically observed intensities in the region. To assess PSHA models for California, a long and consistently interpreted intensity record is needed. For this purpose, the California Historical Intensity Mapping Project (CHIMP) has compiled a dataset that combines and reinterprets intensity information that has been stored in disparate and sometimes hard-to-access locations. The CHIMP dataset also includes new observations of intensity from archival research and oral history collection. Version 1 of the dataset includes 46,502 intensity observations for 62 earthquakes with estimated magnitudes ranging from 4.7 to 7.9. The 162 yr of shaking data show observed shaking lower than expected from seismic hazard models. This discrepancy is reduced, but persists, if historical intensity data for the largest earthquakes are smoothed to reduce the effects of spatial undersampling. Possible reasons for this discrepancy include other limitations of the CHIMP dataset, the hazard models, and the possibility that California seismicity throughout the historical period has been lower than the long-term average. Some of these issues may also explain similar discrepancies observed for Italy and Japan.

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.

Hazard-Consistent Earthquake Scenario Selection for Seismic Slope Stability Assessment

Design ground shaking intensity, based on probabilistic seismic hazard analysis (PSHA) maps, is most commonly used as a triggering condition to analyze slope stability under seismic loading. Uncertainties that are associated with expected ground motion levels are often ignored. This study considers an improved, fully probabilistic approach for earthquake scenario selection. The given method suggests the determination of the occurrence probability of various ground motion levels and the probability of landsliding for these ground motion parameters, giving the total probability of slope failure under seismic loading in a certain time interval. The occurrence hazard deaggregation technique is proposed for the selection of the ground shaking level, as well as the magnitude and source-to-site distance of a design earthquake, as these factors most probably trigger slope failure within the time interval of interest. An example application of the approach is provided for a slope near the highway in the south of Sakhalin Island (Russia). The total probability of earthquake-induced slope failure in the next 50 years was computed to be in the order of 16%. The scenario peak ground acceleration value estimated from the disaggregated earthquake-induced landslide hazard is 0.15g, while the 475-year seismic hazard curve predicts 0.3g. The case study highlights the significant difference between ground shaking scenario levels in terms of the 475-year seismic hazard map and the considered fully probabilistic approach.

Seismic source modeling and probabilistic seismic hazard analysis for Bangladesh

The probabilistic seismic hazard analysis (PSHA) has been performed for Bangladesh using background seismicity, crustal fault, and subduction zone source models. The latest ground motion prediction equations (GMPEs) that are developed using global data sets have been used to estimate ground motion. The uncertainties in seismic sources and GMPEs to estimate ground motion are accounted using the logic tree approach. The activity rates of the background and regional seismicity sources are estimated using a declustered and complete catalog of the study regions. The activity rates of the crustal fault and subduction zone sources are estimated from the geodetic strain rates using the well-accepted relationships. The peak ground acceleration (PGA) and spectral acceleration (SA) at spectral periods of 0.2, 0.5, 1.0, 2.0, 5.0, and 10.0 s have been estimated at a grid size of 0.250 at the bedrock ground condition. The PGA and SA maps of various spectral periods have been prepared for Bangladesh for both 10% and 2% probability of exceedance in 50 years. These seismic hazard maps can be used for seismic risk management of Bangladesh.

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.

Seismic hazard maps of Peshawar District for various return periods

Abstract. Probabilistic seismic hazard analysis of Peshawar District has been performed for a grid size of 0.01∘. The seismic sources for the target location are defined as the area polygon with uniform seismicity. The earthquake catalogue was developed based on the earthquake data obtained from different worldwide seismological networks and historical records. The earthquake events obtained at different magnitude scales were converted into moment magnitude using indigenous catalogue-specific regression relationships. The homogenized catalogue was subdivided into shallow crustal and deep-subduction-zone earthquake events. The seismic source parameters were obtained using the bounded Gutenberg–Richter recurrence law. Seismic hazard maps were prepared for peak horizontal acceleration at bedrock level using different ground motion attenuation relationships. The study revealed the selection of an appropriate ground motion prediction equation is crucial for defining the seismic hazard of Peshawar District. The inclusion of deep subduction earthquakes does not add significantly to the seismic hazard for design base ground motions. The seismic hazard map developed for shallow crustal earthquakes, including also the epistemic uncertainty, was in close agreement with the map given in the Building Code of Pakistan Seismic Provisions (2007) for a return period of 475 years on bedrock. The seismic hazard maps for other return periods i.e., 50, 100, 250, 475 and 2500 years, are also presented.

Seismic hazard maps of Egypt based on spatially smoothed seismicity model and recent seismotectonic models

An earthquake catalogue of Egypt is a vital element for seismotectonic and seismic hazard studies using different approaches. Therefore, an updated earthquake catalogue for Egypt and its circumference is collected. The collected earthquake catalogue includes the historical and the instrumental seismic records. Data sets of all earthquakes with a magnitude (M), M ≥ 3, on any magnitude scale mentioned in local, regional, and international sources are included. The collected catalogue contains 5894 earthquakes. Contaminated events, low reliability, and duplicate events are identified using the available current knowledge and then have been removed. Special priorities were considered through the removing process. The processed catalogue contains 4776 earthquakes. We searched for the moment magnitude (Mw) of each earthquake in the original data sources and publications. When Mw is not available, the moment magnitude is calculated through empirical relationships which are obtained in the current study using the orthogonal regression method. The catalogue is de-clustered aiming to eliminate the dependent events using three de-clustering techniques. Completeness test of the entire catalogue is performed. Based on the processed catalogue, the spatial diversity of the Egyptian seismic activity is represented for the first time. The a-value, b-value, and the maximum estimated magnitude of the recently delineated Egyptian seismic source zones are calculated. Probabilistic seismic hazard assessment (PSHA) is calculated using two recently delineated seismotectonic models, two different smoothed seismicity maps and three ground motion prediction equations (GMPEs). Different seismotectonic models and GMPEs are put into the logic-tree practice for treating the epistemic uncertainties accompanying the hazard calculations. The produced seismic hazard maps represent the peak ground acceleration (PGA) and the spectral acceleration (SA) corresponding to 0.2 and 1 s (s) natural vibration periods for 475 and 2475 years return periods (RPs). The produced hazard maps illustrate that the Gulf of Aqaba area is exposed to the highest acceleration, while the Western Desert is exposed to the lowest ones. For instance, the map of PGA for 475 years RP shows PGA values of 0.229 g close to the Gulf of Aqaba and 0.005 g at the Western Desert.

Estimation of probabilistic seismic hazard for Aizawl city in North Eastern India (NEI)

It is common practice to describe seismic hazard in terms of Peak Ground Acceleration (PGA) and Spectral acceleration (Sa). Response spectrum representation of ground motion is directly applicable in structural response analysis. However, in India, engineers have been using a standard response spectral shape as recommended by the code IS-1893:2016 all over the country, modified only by a zonal factor representing the PGA of unknown probability of occurrence. This approach is silent about the various seismo-tectonic sources and non-uniform level of hazard at different parts of India. Thus, the expected or desired design life of structures cannot rationally harmonize with existing earthquake hazard and economical construction practices. Whereas, the underestimation of the hazard will lead to questionable safety margins, overestimation makes the projects uneconomical and hence social goal suffers in either case. It is in this context, Probabilistic Seismic Hazard Assessment (PSHA) that addresses engineering safety issues with quantifiable risk levels has become more popular. Now-a-days, seismic hazard maps are prepared in different countries for a given annual frequency of exceedance. With this in mind, probabilistic seismic hazard for Aizawl City has been prepared.In this study, we have estimated seismic hazard for different return period in Aizawl city. The active fault within 300 km radius of the city are considered for this study. The seismic hazard values estimated in this study will be useful for the structural designers of Aizawl city and its adjacent region to design various types of Engineering Structures.

A new ground motion prediction model for Northeast India (NEI) shallow crustal

In this paper, a new ground-motion prediction model (GMPE) for North-eastern India (NEI) is developed based on the available recorded events. NEI has already faced several high magnitude earthquakes (moment magnitude [Mw ]>7.0) during the period 1200 to 2018. It is difficult to develop GMPE and estimating the seismic hazard of NEI, due to sparse recorded strong motion database. To date, seismic hazard maps for NEI have not been prepared. All developed countries have developed seismic hazard maps for their cities using region-specific GMPE. So, to prepare the seismic hazard maps of NEI, a ground motion prediction model will be required. The success of earthquake hazard mitigation depends to a large extent on how accurately the ground motion hazard can be estimated at a vulnerable site. The GMPE developed in this study has been compared with other ground-motion models as well as with the available limited recorded strong motion database. Based on the comparison, it is observed that the new model is reasonably correct as the model is unbiased with respect to both magnitude and hypocentral distance. This model needs to be upgraded as and when more recorded strong ground motion database is available for this region.

Scenario-based seismic hazard analysis using spectral element method in northeastern Pakistan

Seismic hazard analysis is carried out in this study by estimating ground motion for hypothetical earthquakes in the area of Muzaffarabad, Pakistan, with the MT solution of the 2005 Kashmir earthquake. The earth’s topography influences seismic waves by scattering and reflecting it, thereby causing spatial variation in seismic response. Using the moment tensor solution of the 2005 Kashmir earthquake, we perform 25 spectral element method (SEM)-based 3D simulations along major faults in the study area. The SEM model incorporates the topography and homogeneous half-space characteristics. Our results show that, beside topography, the relative location of the source with respect to slopes also has an influence on the observed variation in ground shaking amplitudes. By integrating the mean and standard deviation of estimated ground shaking from 25 simulations, we present a seismic hazard map for the study area. The map summarizes the topographic and potential source location effect on seismic-induced ground shaking in the study area. It provides a classification from hazardous to safe in relative terms and can be used as a guide in earthquake preparedness.

Seismic hazard assessment for mainland China based on spatially smoothed seismicity

Probabilistic seismic hazard assessment for mainland China is carried out by using spatially smoothed seismic source models obtained using the historical earthquake catalogue and two kernel smoothing techniques. The first one smooths the cumulative event count and the second one smooths the earthquake occurrence rate. For the analysis, the completeness of the catalogue is assessed and the k-mean seismic analysis results are used to aid the assignment of the regions. It is shown that the estimated parameters for the Gutenberg-Richter relation by using the maximum likelihood–based approach are consistent with those estimated by using the least-squares based approach by considering unequal observation periods. The developed seismic hazard maps indicate that the use of the smoothed source model obtained by smoothing the cumulative event count leads to spatially smeared seismic hazard. The use of the smoothed source model obtained based on smoothing the occurrence rate results in the seismic hazard map to have more spatial details. The seismic hazard assessment results indicate that, on average, the ratio of the 2475-year to 475-year return period values of PGA is about 2 and the ratio of the 2475-year to 50-year return period values of PGA is about 8. These ratios are associated with large scatters. A comparison of the normalized UHS and the Chinese design code recommended standardized design spectrum indicates that the latter is conservative as compared to the former for vibration periods outside of 0.1 to 0.2 s, and that the shape of the latter differs from that of former.

Seismic Hazard Vulnerability of Bengkulu City, Indonesia, Based on Deterministic Seismic Hazard Analysis

Bengkulu City is one of cities in Indonesia, which is located on the west coastline of Sumatra. Within last two decades, Bengkulu City had undergone at least two large earthquakes with magnitudes ≥ Mw 7.0. This paper presents a study of deterministic seismic hazard for Bengkulu City. The hazard analysis is initiated by determining the controlling earthquake. Site investigation results are also studied for seismic ground response analysis. Analysis is performed by propagating seismic wave to investigate seismic behaviour during earthquake. Three parameters including peak ground acceleration, spectral acceleration at 0.2 s (SA at 0.2 s), and spectral acceleration at 1 s (SA at 1 s) are analysed to generate seismic hazard maps. In general, this study could help people to understand seismic hazard in Bengkulu City. The results also could recommend local engineers to consider earthquake in structural design and spatial plan in Bengkulu City.

Seismic Hazard Assessment of Dhanbad City, India, by deterministic approach

Dhanbad is the largest producer of coal in the state of Jharkhand, India, and hence, it is one of the most important cities in the country. Considering the present-day importance and future growth of the city, assessment of seismic hazard is extremely needed, especially for the mining authorities and the city planners. The prime objective of this study is to develop seismic hazard map of Dhanbad City for the bedrock level following the deterministic approach. In view of the absence of the region-specific Ground Motion Prediction Equations, the concept of logic tree comprising four different attenuation models is adopted. It is observed that the Peak Ground Acceleration in the range of 0.10–0.26 g may be expected in the city. Specifically, southern blocks of the city such as Baghmara, Jharia and Baliapur are found to be most vulnerable to the seismic hazard. Besides, developed seismic hazard map is divided into four zones and smooth acceleration response spectrums are proposed for the zones as per the expected seismicity in different parts of the city.