Earthquake Scenarios Research Articles

A review of performance evaluation of RC-infilled frames under earthquake scenarios

A review of performance evaluation of RC-infilled frames under earthquake scenarios

Ground motion models for Fourier amplitude spectra and response spectra using Machine learning techniques

AbstractOne of the main objectives in engineering seismology or in seismic hazard studies is to estimate the possible ground motion for a given earthquake scenario. In the sparse data regions mostly the ground motion models (GMM) are developed using either seismological models or hybrid empirical approaches. However, if these GMMs do not accommodate the regional seismological attributes, a large uncertainty in ground motion estimates is possible. To overcome this concern, scaling 5% damped Pseudo Spectral Acceleration (PSA) from Fourier amplitude spectra (FAS) proves to be physically consistent as it can capture both spatial and temporal characteristics of the ground motion. Hence, the present study aims to develop a GMM for PSA using FAS and significant duration as the predictor variables. However, since there are few GMMs available for FAS, the current study also aims to develop a GMM for FAS using the earthquake parameters as the predictor variables for intraplate regions. This article employs an Artificial Neural Network (ANN) to develop both GMMs using the Next Generation Attenuation (NGA)‐East database for both horizontal (Effective Amplitude spectra for FAS and RotD50 component for PSA) and vertical components. To verify the performance of the developed models, the residuals analysis and parametric studies have been performed. The parametric study shows that the GMMs can capture the magnitude and distance scaling consistent with the observations. Further, the PSA GMM compared with the global GMMs and it is observed that the predictions lie well within the median of all the available models, proving the models’ effectiveness in estimating the ground motion predictions for future data. The developed model can be used only within the considered ranges of the predicted variables such as rupture distances between [19.05–1000] km, the Mw ranges from [3.12–5.74] with Vs30 in the range of [209–2000] m/s.

Optimal siting of substations of traction power supply systems considering seismic risk

The traction power supply system (TPSS) is a critical infrastructure that provides electrified railways with power. However, its safe and reliable operation is threatened by earthquake disasters. Due to the strong randomness, uneven spatial distribution, and destructive risk of earthquake disasters, it is crucial to develop reasonable planning schemes to mitigate seismic risks of the system. This paper proposes a substation optimal siting method considering seismic risks. By establishing the chain circuit model of the TPSS and employing the dynamic power flow calculation method, the power loss of the system is obtained. By integrating the earthquake scenario simulation and substation fragility analysis, the substation seismic risk is calculated through Monte Carlo simulation. On this basis, the optimization model for substation site selection is formulated, aiming to minimize both the system power loss and the substation seismic risk while adhering to constraints of construction cost, operating safety, and geographical locations. The Pareto optimal solutions are then obtained. Simulation analysis based on actual system parameters shows that compared with traditional site selection methods, the proposed method can effectively mitigate system seismic risks while considering system power loss, providing theoretical bases for the disaster prevention and mitigation in the TPSS planning.

Virtual Scenarios of Earthquake Early Warning to Disaster Management in Smart Cities Based on Auxiliary Classifier Generative Adversarial Networks.

Effective response strategies to earthquake disasters are crucial for disaster management in smart cities. However, in regions where earthquakes do not occur frequently, model construction may be difficult due to a lack of training data. To address this issue, there is a need for technology that can generate earthquake scenarios for response training at any location. We proposed a model for generating earthquake scenarios using an auxiliary classifier Generative Adversarial Network (AC-GAN)-based data synthesis. The proposed ACGAN model generates various earthquake scenarios by incorporating an auxiliary classifier learning process into the discriminator of GAN. Our results at borehole sensors showed that the seismic data generated by the proposed model had similar characteristics to actual data. To further validate our results, we compared the generated IM (such as PGA, PGV, and SA) with Ground Motion Prediction Equations (GMPE). Furthermore, we evaluated the potential of using the generated scenarios for earthquake early warning training. The proposed model and algorithm have significant potential in advancing seismic analysis and detection management systems, and also contribute to disaster management.

Deterministic seismic hazard analysis from physics-based earthquake simulations in the Eastern Betics (SE Iberia)

The low frequency of large destructive earthquakes in the Eastern Betics (SE Iberian Peninsula), not recorded in the instrumental seismic catalog, complicate the estimation of the maximum ground motion that could be reached. Knowing the characteristics and behavior of these large seismic ruptures is crucial for the study of seismic hazard. In this work, we have used a physics-based earthquake simulator to generate a 100 kyr catalog of seismic ruptures associated with seismogenic faults bordering the quaternary Guadalentin and Bajo Segura basins. From these ruptures, we have selected maximum earthquake scenarios, and those associated with certain probabilities of exceeding a severe magnitude from the synthetic catalog. The estimation of maximum peak accelerations (PGA) by means of ground motion prediction equations include a possible site amplification that we have calculated from a detailed geotechnical classification of soils. According to the simulations, the modeled faults have the capacity to generate maximum earthquakes with magnitudes ranging MW 6.7–7.4. Densely populated urban areas located along the Guadalentin valley, such as Lorca, could be subject to site-dependent PGA values close to 0.6 g on the Alhama de Murcia fault trace. Similar ground motion would affect the coastline of SE Alicante province when evaluating the maximum simulated event in the Bajo Segura offshore fault. But already from magnitudes around MW ∼ 6, PGA estimations exceed critical values of 0.5 g at the south side of the Bajo Segura basin and the city of Murcia, highly dependent of ground-motion amplification induced by thick deposits of very soft and saturated soils. Our scenarios reflect that other factors such as fault geometry, kinematics and the capability observed in the simulations to generate multi-fault ruptures also affect the spatial distribution of maximum ground motion in this region. We expect that this evaluation could contribute as an improvement guideline for future strong motion prediction studies prior to the settlement of new urban infrastructures in the Eastern Betics.

A database and empirical model for earthquake post-loss amplification

The impact of destructive earthquakes might exceed the local capacity to cope with disasters and lead to an increase in the reconstruction costs. This phenomenon is commonly termed as post-loss amplification, and its main causes include the increase in the cost of construction materials and labor due to the sudden demand, the need to reconstruct following higher standards, or other unexpected costs. We reviewed 70 past earthquakes to identify events where post-loss amplification was observed, and collected a set of seismogenic, socio-economic, geographical, and impact variables for those events. Using this database, we developed two models to predict post-loss amplification, using a composite indicator that reflects the level of destruction in the region, or a parameter that characterizes the frequency of the event. This study indicates increased costs (>10%) for events where the economic losses exceed 1% of the regional gross domestic product, or for events with an estimated return period of at least 10 years. These models can be applied directly in the amplification of economic losses in earthquake scenarios or in probabilistic seismic risk assessment.

Evidence of Seattle Fault Earthquakes from Patterns in Deep-Seated Landslides

ABSTRACT Earthquake-induced landslides can record information about the seismic shaking that generated them. In this study, we present new mapping, Light Detection and Ranging-derived roughness dating, and analysis of over 1000 deep-seated landslides from the Puget Lowlands of Washington, U.S.A., to probe the landscape for past Seattle fault earthquake information. With this new landslide inventory, we observe spatial and temporal evidence of landsliding related to the last major earthquake on the Seattle fault ∼1100 yr before present. We find spatial clusters of landslides that correlate with ground motions from recent 3D kinematic models of Seattle fault earthquakes. We also find temporal patterns in the landslide inventory that suggest earthquake-driven increases in landsliding. We compare the spatial and temporal landslide data with scenario-based ground motion models and find stronger evidence of the last major Seattle fault earthquake from this combined analysis than from spatial or temporal patterns alone. We also compare the landslide inventory with ground motions from different Seattle fault earthquake scenarios to determine the ground motion distributions that are most consistent with the landslide record. We find that earthquake scenarios that best match the clustering of ∼1100-year-old landslides produce the strongest shaking within a band that stretches from west to east across central Seattle as well as along the bluffs bordering the broader Puget Sound. Finally, we identify other landslide clusters (at 4.6–4.2 ka, 4.0–3.8 ka, 2.8–2.6 ka, and 2.2–2.0 ka) in the inventory which let us infer potential ground motions that may correspond to older Seattle fault earthquakes. Our method, which combines hindcasting of the surface response to the last major Seattle fault earthquake, using a roughness-aged landslide inventory with forecasts of modeled ground shaking from 3D seismic scenarios, showcases a powerful new approach to gleaning paleoseismic information from landscapes.

A Population-Based Performance Evaluation of the ShakeAlert Earthquake Early Warning System for M 9 Megathrust Earthquakes in the Pacific Northwest, U.S.A.

ABSTRACT We evaluate the potential performance of the ShakeAlert earthquake early warning system for M 9 megathrust earthquakes in the Pacific Northwest (PNW) using synthetic seismograms from 30 simulated M 9 earthquake scenarios on the Cascadia subduction zone. The timeliness and accuracy of source estimates and effectiveness of ShakeAlert alert contours are evaluated with a station-based alert classification scheme using an alert threshold equal to the target threshold. We develop a population-based alert classification method by aligning a population grid with Voronoi diagrams computed from the station locations for each scenario. Using raster statistics, we estimate the PNW population that would receive timely accurate alerts during an offshore M 9 earthquake. We also examine the range of expected warning times with respect to the spatial distribution of the population. Results show that most of the population in our evaluation region could receive alerts with positive warning times for an alert threshold of modified Mercalli intensity (MMI) III, but that late and missed alerts increase because the alert threshold is increased. An average of just under 60% of the population would be alerted for MMI V prior to the arrival of threshold level shaking. Large regions of late and missed alerts for thresholds MMI IV and V are caused by delays in alert updates, inaccurate FinDer source estimates, and undersized alert contours due to magnitude underestimation. We also investigate an alerting strategy where ShakeAlert sends out an alert to the entire evaluation region when the system detects at least an M 8 earthquake along the coast. Because large magnitude offshore earthquakes are rare in Cascadia, overalerting is most likely to occur from an overestimated M 7+ on the Gorda plate. With appropriate criteria to minimize overalerting, this strategy may eliminate all missed and late alerts except at sites close to the epicenter.

Feasibility of a self-powered movable seawall using microtidal energy in Japan

The technology for closing port entrances using movable gates as a tsunami countermeasure has recently garnered increasing attention in Japan. However, it is not possible to mechanically operate the gates if power is lost because of a disaster. Accordingly, this study proposes a self-powered movable seawall system that utilizes microtidal energy generated by port closure for operating the gates. As tidal ranges in Japan are not favorable for power generation, the feasibility of the proposed system was assessed at 56 ports throughout Japan. The self-powered system was found feasible at nine ports during both spring and neap tide and at 14 ports during spring tide, whereas the tidal range was too small to operate the system at the other 33 ports. Moreover, 20 feasible ports were located such that tsunamis are predicted to occur in the scenario of a megathrust earthquake, which has a 90 % occurrence probability in the next 40 years. Surplus electricity is expected to be generated on-site with the proposed system, even if a power outage occurs, which is especially valuable for urgent disaster response and business continuity in industrial areas. Our findings outline a synergistic system between disaster prevention and the use of renewable energy.

Improvement to stochastic tsunami hazard analysis of megathrust earthquakes for western Makran subduction zone

The Makran Subduction Zone (MSZ) is one of the world's most tsunami-prone regions. In the present study, tsunami hazards associated with potential MSZ earthquakes are evaluated using stochastic earthquake rupture modeling, which allows for the incorporation of uncertainties related to slip heterogeneity. Along the western segment of the MSZ, where tsunami hazard studies have received less attention, megathrust earthquakes with moment magnitudes of Mw 8.5, 8.7, and 8.9 are considered. The source parameters of 600 stochastic earthquake scenarios are calculated using the scaling relationships of Goda et al. (2016), which represent significant improvements over previous scaling relationships by taking into account the uncertainty of multiple source parameters and the coverage of a wide range of earthquake magnitudes. In order to simulate tsunami propagation and inundation, the nonlinear shallow water equations are used in four-level nested grid model domains .According to the calculated slip fields, the seismic source characteristics provided by stochastic source models significantly change within the earthquakes scenarios with identical magnitudes and may completely differ from the results of traditional uniform-slip source models. The results of the 600 Monte Carlo tsunami simulations demonstrate that even extremely large earthquakes in the west MSZ do not lead to significant tsunamis along the eastern coastal regions of Makran. The average maximum wave heights of 8, 10, and 17 m along the western Makran coasts, which correspond to the Mw 8.5, 8.7, and 8.9 scenarios, respectively, emphasize the severe potential threat of a possible tsunamigenic event in the west of the MSZ to the Iranian coasts. In addition, the significant difference between the maximum wave heights of the 10th and 90th percentiles for each scenario demonstrates the large variability of tsunami heights resulting from uncertainties associated with stochastic seismic source modeling. Thus, it can be concluded that the tsunami hazard parameters estimated by simple uniform-slip source models need to be revised in future tsunami risk assessment studies.

A multi-scenario based micro seismic hazard assessment of the Bhuj City, western India incorporating geophysical and geotechnical parameters

The micro-seismic hazard assessment (micro-SHA) of the Bhuj city (highest seismic zone V) has been accomplished considering seismotectonic as well as shallow subsurface modeling through geophysical (multi-channel analysis of surface waves (MASW) survey at 19 sites) and geotechnical parameters from 28 boreholes distributed in the entire Bhuj city. The average shear wave velocity through the MASW survey at 30 m depth (VS30) is estimated in the range of 400–915 m/s (NEHRP C-type and B-type soil classes). Seismotectonically justified a total of 54 scenario-earthquakes (SEQs) along all major faults have been considered to evaluate the strong ground motion at generic soil level having a shear wave velocity of 760 m/s and depth of 12–28 m. The surface level strong motion (SM) has been estimated through ground response analysis preparing soil models along all boreholes. The PGA at the surface in Bhuj city has been estimated in the range of 528 cm/s2 to 1020 cm/s2; highest in the central-western part of the Bhuj city where clay with high plasticity is present. The mean-spectral acceleration over the study area for 0.2 s (corresponding to 1-2 story), 0.55 s (4-5 story), 1sec (high rise) and 1.25 s period (large structures) are prepared at the surface from all scenario earthquakes. The amplification of SM in the Bhuj city is computed in the range of 1.7–3.7.

An offshore non-ergodic ground motion model for subduction earthquakes in Japan Trench area

With the improvement of the world’s largest seafloor observation network (S-net) and the increase in the quantity and quality of records, the ergodic assumptions can be further relaxed in the modeling of offshore ground motion models (GMMs). This allows accounting for systematic and repeatable source, site, and path effects to further understand the characteristics of offshore ground motion in the Japan Trench region. We developed an offshore ergodic backbone GMM for subduction earthquakes and classified the sites into four categories using horizontal–vertical response spectral ratio to investigate site amplification. The offshore ergodic GMM is applicable for subduction earthquake scenarios with moment magnitudes ranging from 4.0 to 7.4 and rupture distances ranging from 10 to 300 km. Comparing offshore ergodic GMMs with onshore GMMs for subduction earthquakes, we found that offshore GMMs were significantly different from onshore GMMs, especially in the long-period and unburied states. Then a new offshore non-ergodic GMM was developed based on the offshore ergodic GMM. The systematic and repeatable source and site effects were captured by the spatially varying coefficients represented by Gaussian processes, while the systematic and repeatable path effects were captured by cell-specific anelastic attenuation proposed by Dawood and Rodriguez-Marek (2013), calculated with the Cohen-Sutherland computer graphics algorithm. The non-ergodic GMM revealed systematic and repeatable source, site, and path effects that were not captured by the ergodic GMM. Moreover, the non-ergodic GMM showed reduced aleatory variability and epistemic uncertainty on ground motion estimation compared to ergodic GMM. The reduction of aleatory variability and epistemic uncertainty had a significant impact on probabilistic seismic hazard analysis. Quantifications of these results are contributed to conduct reasonable seismic design and seismic risk assessment for marine engineering in offshore regions vulnerable to strong subduction earthquakes.

Constraining Historical Earthquake Sequences With Coulomb Stress Models: An Example From Western Türkiye

AbstractKnowledge of earthquake source faults is crucial for the calculation of robust Coulomb stress models. However, source faults are often poorly constrained, especially for pre‐instrumental events, and these historical earthquakes are commonly studied with little or no consideration of other nearby events. We introduce an approach using Coulomb Stress Transfer (CST) modeling to investigate historical earthquake sequences and constrain possible source faults. Using historical and instrumental records from the Büyük Menderes Graben, western Türkiye, we create an ensemble of earthquake sequences featuring multiple rupture scenarios for individual earthquakes, and model both coseismic and interseismic CST. We filter and evaluate the models based on criteria to gain knowledge on historical earthquakes and their source faults and assess the current stress state and related seismic hazard of the investigated fault network. For our study area, the results provide further constraints on the source faults of several historical earthquakes, including the destructive MW 7.0 earthquake in 1899. The approach presented herein is applicable to other tectonically active areas where the causative faults of historical earthquakes are poorly constrained from existing data sets (e.g., paleoseismology, damage records), providing a new tool to help decipher historical earthquake sequences and improve modeling studies.

A Damping Modification Factor Prediction Model for Horizontal Displacement Spectrum from Shallow Crustal and Upper-Mantle Earthquakes in Japan Accounting for Site Conditions

ABSTRACT This article presents damping modification factors (DMFs) for the horizontal component of the strong-motion records generated by the shallow crustal and upper-mantle earthquakes in Japan. This model can be used to scale a 5% damped design spectrum that does not associate with a known magnitude and rupture distance to obtain a design spectrum with the desirable damping ratios. Our previous study suggested that the site effect on DMF was significant, and we used site class as the site-effect parameter. We used a quadratic function of damping ratio in a natural logarithm scale to model the effect of damping ratios and we used fourth-order polynomials of the natural logarithm spectral period to present the effect of the spectral period when the spectral period is over 0.06 s. The between-event, between-site, and within-site standard deviations can be described by the linear function of the damping ratio in a natural logarithm scale. The between-event standard deviations are smaller than the within-event standard deviations and the between-site standard deviations are less than the within-site ones at many spectral periods. Reasonable displacement spectra can be obtained by using the DMF model from this study to scale the 5% damped displacement spectra. The differences in the DMF values from the three types of earthquakes are moderate at many spectral periods and the predicted DMF values from this study are similar to those from other studies at some spectral periods, but the differences are considerable at the other spectral periods. The variation trend of the DMF values suggests that the predicted DMF values may reach the theoretic value of 1.0 at some spectral periods over 5.0 s. Residual distribution analysis suggested that the bilinear function of magnitude and fault-top depth can be used in a model for scenario earthquakes.

Red-light thresholds for induced seismicity in the UK

Induced earthquakes pose a serious hurdle to subsurface energy development. Concerns about induced seismicity led to terminal public opposition of hydraulic fracturing in the UK. Traffic light protocols (TLPs) are typically used to manage these risks, with the red-light designed as the last-possible stopping-point before exceeding a risk tolerance. We simulate trailing earthquake scenarios for the UK, focusing on three risk metrics: nuisance, damage, and local personal risk (LPR) – the likelihood of building collapse fatality for an individual. The severity of these risks can spatially vary (by orders-of-magnitude), depending on exposure. Estimated risks from the Preston New Road earthquakes are used to calibrate our UK earthquake risk tolerances, which we find to be comparable to Albertan (Canadian) tolerances. We find that nuisance and damage concerns supersede those from fatality and that the safest regions for Bowland Shale development would be along the east coast. A retrospective comparison of our TLP result with the Preston New Road case highlights the importance of red-light thresholds that adapt to new information. Overall, our findings provide recommendations for red-light thresholds (ML 2-2.5) and proactive management of induced seismicity – regardless of anthropogenic source.

Potential Seismic Hazard in Seoul, South Korea: A Comprehensive Analysis of Geology, Seismic, and Geophysical Field Observations, Historical Earthquakes, and Strong Ground Motions

ABSTRACT A series of moderate-size (Mw 4.0–6.0) earthquakes occurred in South Korea after the 2011 Mw 9.0 Tohoku–Oki megathrust earthquake, incurring public concern about possible occurrence of devastating earthquakes in Seoul—the capital city of South Korea, where historical seismic damage was reported. The seismicity is distributed in Seoul, being dominated by strike-slip earthquakes. The fault planes are oriented in north-northeast–south-southwest, which is a favorable direction to respond to the ambient stress field. Higher rates of seismicity are observed in the northwestern Seoul at depths of <10 km. Micro-to-small earthquakes occur episodically in the central Seoul along the Chugaryeong fault system that traverses Seoul in north–south. Seismic, geophysical, and geological properties illuminate the fault structures. Stochastic modeling of ground motions reproduces the seismic damages of historical earthquakes reasonably, supporting the occurrence of devastating historical earthquakes in Seoul. The seismicity distribution, focal mechanism solutions, geological features, and seismic and geophysical properties suggest the possible presence of earthquake-spawning blind faults in Seoul. The peak ground motions are assessed for moderate-size scenario earthquakes (Mw 5.4 with focal depth of 7 km) at six representative subregions in Seoul. The upper bounds of peak ground accelerations reach ∼11 m/s2. The seismic damage potentials for moderate-size earthquakes are high in most areas of Seoul, particularly around river sides covered by alluvium.

Regional spectral characteristics, quality factor and site responses in western-central Sichuan, China (II): Application to stochastic ground motion simulation

The stochastic finite-fault approach was used to model the 2022 Luding earthquake with a magnitude of Mw 6.6 in China at 16 selected near-field stations. To investigate the impact of the site effect on the synthetic results, two models were taken into account: One model was obtained from the generalized inversion technique, and the other model was obtained from the horizontal-to-vertical spectral ratio method. The high-frequency attenuation parameter was estimated to be 0.040 s and the value of 4.0 MPa for the stress parameter was adopted. Comparisons of the recorded and simulated Fourier amplitude spectrum, pseudospectral acceleration, peak ground acceleration, and peak ground velocity were performed to investigate the capability of the selected input parameters. In addition, the model bias, simulated peak ground acceleration and peak ground velocity were calculated by the local site amplification estimated by the two methods. The results show that the site effects estimated by the generalized inversion technique can well simulate the high-frequency response spectra and Fourier amplitude spectrum and can provide peak ground acceleration and peak ground velocity values consistent with the recorded values, while the local site amplification roughly calculated by the horizontal-to-vertical ratio method underestimates the main ground motion characteristics. Furthermore, strong-motion records with the same magnitude but different hypocentral distance ranges in the generalized inversion technique are used to estimate near-surface site effects, which shows that the distance range has a small impact on the estimation of local site amplification. Model parameters that performed well in this study provide confidence in understanding and quantifying seismic hazards in the Luding area from earthquake scenarios with different magnitudes.

The seismic hazard from the Lembang Fault, Indonesia, derived from InSAR and GNSS data

Abstract. A growing number of large cities are located near poorly understood faults that have not generated a significant earthquake in recent history. The Lembang Fault is one such fault located near the city of Bandung in West Java, Indonesia. The slip rate on this fault is debated, with estimates ranging from 6 to 1.95–3.45 mm yr−1, derived from a GNSS (global navigation satellite system) campaign and geological measurements respectively. In this paper we measure the surface deformation across the Bandung region and resolve the slip rate across the Lembang Fault using radar interferometry (InSAR – interferometric synthetic aperture radar) analysis of 6 years of Sentinel-1 satellite data and continuous GNSS measurements across the fault. Our slip rate estimate for the fault is 4.7 mm yr−1, with the shallow portions of the fault creeping at 2.2 mm yr−1. Previous studies estimated the return period of large earthquakes on the fault to be between 170–670 years. Assuming simplified fault geometries and a reasonable estimate of the seismogenic depth we derive an estimated moment deficit equivalent to magnitude 6.6–7.0 earthquakes, indicating that the fault poses a very real hazard to the local population. Using the Global Earthquake Model OpenQuake engine we calculate ground motions for these two earthquake scenarios and estimate that 1.9–2.7 million people within the Bandung metropolitan region would be exposed to ground shaking greater than 0.3 g. This study highlights the importance of identifying active faults, understanding their past activity, and measuring the current strain rates of smaller crustal active faults located near large cities in seismic zones.

Dynamic performance of the Mosque-Cathedral of Córdoba under different earthquake scenarios: The Abd al-Rahman I sector

The Mosque-Cathedral of Córdoba is one of the most important monuments in Spain. Owing to its authenticity, its integrity and its influence on later architecture, it was declared as a World Heritage Site by the UNESCO in 1984. The monument is located in Andalusia, in southern Spain. This region presents a moderate seismic hazard, and it is affected by two kinds of seismic sources: a) far away earthquakes of large/very large magnitude; b) close earthquakes of moderate magnitude. Particularly, the Mosque-Cathedral had to endure the well-known 1755 Lisbon's earthquake (Mw = 8.5, at 488 km) and the 1504 Carmona earthquake (Mw = 6.8, at 82 km). This research has analysed its dynamic behaviour under several earthquake scenarios: code-base response spectrum, previous historic earthquakes and fault maximum magnitude earthquakes. However, after the seismic hazard analysis and due to the lack of faults registered surrounding the building, no worst-case scenario considering the maximum expected magnitude has been found. Owing to the complexity of the building, this work has focused on the Abd al-Rahman I sector, which is the most aged part, dating from the VIII century. A refined 3D numerical model has been developed and calibrated through free ambient vibration tests. The distribution of the maximum amplitudes (internal displacements and absolute accelerations) under the different scenarios has been comparatively presented. Also, the seismic performance has been assessed considering the drifts and the damage expected. The results showed that the damage would be concentrated in the contact between the arcades and the courtyard wall. Also, the lower part of the North-South closing wall would be damaged. According to the seismic performance, the building is expected to present moderate damage. In contrast, the analysis of the drifts, according to the codes, suggest that the building would resist each damage limit. Also, it was shown that the far fault earthquake scenario is more demanding than the close fault earthquake scenario. Next, it should be noted that the behaviour of the building for a seismic action of 475-year return period is expected to be similar to the far-fault earthquake scenario. The most demanding earthquake scenario has been the 975-year return period one.

Simulation‐based characterization of the variability of earthquake risk to buildings in the near‐field

AbstractRecent advancements in high performance computing platforms and computational workflow for regional‐scale simulations are enabling unprecedented modeling of fault‐to‐structure earthquake processes. Regional simulations resolving ground motions at frequencies relevant to engineered systems are becoming computationally viable and provide a new capability to improve understanding of the geographical distribution and intensity of risk to buildings and critical infrastructure. As computational capabilities advance, it is essential to move beyond illustrative single rupture realizations for scenario earthquake events towards the development of a full suite of rupture realizations that appropriately characterize the range of risk to building systems. The work described in this article investigates the application of a suite of fault rupture realizations with the objective of assessing near‐fault, site‐specific seismic demand variability for building structures. A representative high‐performance regional‐scale computational model is utilized to execute ground motion and building response simulations based on 18 kinematic rupture realizations of an M7 strike‐slip scenario earthquake. The fault rupture models for the scenario earthquake are created by systematically perturbing the hypocenter location and stochastically generating rupture parameters (slip, rise time, rake angle) to represent a breadth of ground motion intensities resulting from the spatial and temporal variabilities of an earthquake rupture process. The resulting seismic demand variability for three‐story (short period) and forty‐story (long period) steel moment‐resisting frame buildings is characterized in terms of the median and distribution of peak inter‐story drift ratio for a range of near‐fault sites. The full suite of 18 fault rupture realizations and approximately 280,000 nonlinear dynamic building simulations indicate that the three‐story building undergoes higher median seismic demand and significantly greater variability of demand at a given site than the forty‐story building, which has important implications for the level of certainty in predicting building performance during an earthquake. The simulations performed provide deeper insight into the relationship between fault rupture parameterization and building response, which is essential information for developing a representative suite of rupture realizations for specific earthquake scenarios.