Ground Velocity Research Articles

Potential of Earthquake Strong Motion Observation Utilizing a Linear Estimation Method for Phase Cycle Skipping in Distributed Acoustic Sensing

AbstractDistributed acoustic sensing (DAS) using existing optical fiber cables facilitates high‐density seismic observation. However, few studies have examined the reliability of the seismic waveform amplitude recorded by DAS. In this study, a DAS network was connected to optical fiber cables installed over a distance of 75 km along a high‐speed train (Shinkansen) railway in the Kumamoto prefecture, Japan. We successfully observed strong motions of the Mj6.6 earthquake (approximately 150 km from the fiber) on 22 January 2022, in Hyuga‐nada, in addition to several small local earthquakes. The observed strong motions from the Mj6.6 earthquake, using DAS, exhibited cycle skipping (clipping) issues due to dynamic range limitations at numerous channels. To address this, we estimated the shaking map, representing maximum strain distributions for Mj6.6, by replacing the clipped data with information from nearby unclipped channels and scaling their RMS amplitudes based on S‐coda (unclipped). Furthermore, we verified the reliability of the amplitude information obtained from DAS by estimating the distance attenuation of seismic waves while correcting for the differences in the structure type and coupling as much as possible. The distance attenuation property of local earthquakes was consistent with that of the peak ground velocities obtained from seismometers, indicating that DAS data acquired using fibers installed on infrastructure (various structures) can also be utilized to assess the spatial distribution of the relative amplitude values along the fiber. Obtaining high‐density seismic motion distributions is important for earthquake early warning and accurate damage estimation of strong motions.

Effects of seismic characteristics and baffle damping on liquid sloshing

The present work concentrates on liquid sloshing in tanks under real seismic excitations with various frequency contents [the ratio of peak ground acceleration (PGA) to peak ground velocity (PGV)] by a finite-difference turbulent model. The turbulence is modeled by the large eddy simulation, and the fluid–structure interaction is resolved by the Virtual Boundary Force method. Thirteen seismic records, covering the low, intermediate and high frequency contents, are adopted to excite nonlinear sloshing waves. Both sloshing wave and hydrodynamic pressure are recorded, and their correlations with the filling level, PGA, PGV and frequency content have been identified. The findings suggest that (1) the sloshing responses are in general positively correlated with the filling level; (2) the sloshing height strongly relates to PGV and frequency content, and the seismic excitation of low frequency and meantime with a larger PGV can trigger more violent sloshing waves than others; and (3) the dynamic pressure along the tank sidewall decreases from the bottom up, which is dominated by PGA at the lower part but the stronger correlation is established with PGV and frequency content at the upper part. Finally, to damp severe sloshing waves, the horizontal, vertical and coupled horizontal and vertical baffles are introduced, and their inhibiting effects are discussed. The present work may guide the design of partially filled storage tanks under seismic excitations.

Ensemble Region-Specific GMMs for Subduction Earthquakes

Abstract This study develops data-driven global and region-specific ground-motion models (GMMs) for subduction earthquakes using a weighted average ensemble model to combine four different nonparametric supervised machine-learning (ML) algorithms, including an artificial neural network, a kernel ridge regressor, a random forest regressor, and a support vector regressor. To achieve this goal, we train individual models using a subset of the Next Generation Attenuation-Subduction (NGA-Sub) data set, including 9559 recordings out of 153 interface and intraslab earthquakes recorded at 3202 different stations. A grid search is used to find each model’s best hyperparameters. Then, we use an equally weighted average ensemble approach to combine these four models. Ensemble modeling is a technique that combines the strengths of multiple ML algorithms to mitigate their weaknesses. The ensemble model considers moment magnitude (M), rupture distance (Rrup), time-averaged shear-wave velocity in the upper 30 m (VS30), and depth to the top of the rupture plane (Ztor), as well as tectonic and region as input parameters, and predicts various median orientation-independent horizontal component ground-motion intensity measures such as peak ground displacement, peak ground velocity, peak ground acceleration, and 5%-damped pseudospectral acceleration values at spectral periods of 0.01–10 s in log scale. Although no functional form is defined, the response spectra and the distance and magnitude scaling trends of the weighted average ensemble model are consistent and comparable with the NGA-Sub GMMs, with slightly lower standard deviations. A mixed effects regression analysis is used to partition the total aleatory variability into between-event, between-station, and event-site-corrected components. The derived global GMMs are applicable to interface earthquakes with M 4.9–9.12, 14≤Rrup≤1000 km, and Ztor≤47 km for sites having VS30values between 95 and 2230 m/s. For intraslab events, the derived global GMMs are applicable to M 4.0–8.0, 28≤Rrup≤1000 km, and 30≤Ztor≤200 km for sites having VS30 values between 95 and 2100 m/s.

A Statistical Approach for the Integration of Multi-Temporal InSAR and GNSS-PPP Ground Deformation Measurements.

Determining and monitoring ground deformations is critical for hazard management studies, especially in megacities, and these studies might help prevent future disaster conditions and save many lives. In recent years, the Golden Horn, located in the southeast of the European part of Istanbul within a UNESCO-protected region, has experienced significant changes and regional deformations linked to rapid population growth, infrastructure work, and tramway construction. In this study, we used Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS) techniques to investigate the ground deformations along the Golden Horn coastlines. The investigated periods are between 2015 and 2020 and 2017 and 2020 for InSAR and GNSS, respectively. For the InSAR analyses, we used sequences of multi-temporal synthetic aperture radar (SAR) images collected by the Sentinel-1 and ALOS-2 satellites. The ground displacement products (i.e., time series and velocity maps) were then cross-compared with those achievable using the Precise Point Positioning (PPP) technique for the GNSS solutions, which can provide precise positions with a single receiver. In the proposed analysis, we compared the ground displacement velocities obtained by both methods by computing the standard deviations of the difference between the relevant observations considering a weighted least square estimation procedure. Additionally, we identified five circle buffers with different radii ranging between 50 m and 250 m for selecting the most appropriate coherent points to conduct the cross-comparison analysis. Moreover, a vertical displacement rate map was produced. The comparison of the vertical ground velocities derived from PPP and InSAR demonstrates that the PPP technique is valuable. For the coherent stations, the vertical displacement rates vary between -4.86 mm/yr and -23.58 mm/yr and -9.50 and -27.77 mm/yr for InSAR and GNSS, respectively.

Ground-Motion Variability for Ruptures on Rough Faults

ABSTRACT Fault roughness influences earthquake rupture dynamics, seismic energy radiation, and, hence, resulting ground motion and its variability. Using 3D dynamic rupture simulations considering a range of rough-fault realizations, we investigate the effects of rupture complexity caused by fault roughness on ground-motion variability, that is, the variability of peak ground acceleration (PGA) and velocity (PGV) as a function of distance. In our analysis, we vary hypocenter locations (leading to unilateral and bilateral ruptures) and fault roughness amplitude to generate a set of magnitude M ≈ 7 strike-slip dynamic rupture simulations. Synthetic seismic waveforms computed on a dense set of surface sites (maximum resolved frequency 5.75 Hz) form our database for detailed statistical analyses. For unilateral ruptures, our simulations reveal that ground-shaking variability (in terms of PGA and PGV) remains nearly constant with increasing distance from the fault. In contrast, bilateral ruptures lead to slowly decreasing ground-motion variability with increasing distance in the near field (less than 20 km). The variability becomes almost constant at large fault distances. We also find that low-amplitude fault roughness leads to ruptures that are likely to generate higher PGA variability than events on faults with high-amplitude roughness. Increasing fault roughness distorts the radiation pattern, thereby reducing directivity effects and, hence, potentially lowering ground-motion variability. The average PGV variability from our rough-fault rupture models is consistent with estimates from empirical ground-motion models (GMMs). However, the average PGA variability exceeds the variability encoded in empirical GMMs by nearly 20%. Hence, our findings have implications for near-source ground-motion prediction in seismic hazard studies, because ground-motion variability depends on details of the earthquake rupture process and is larger than GMM estimates.

Attenuation Relationships for the Horizontal Component of Peak Ground Acceleration (PGAH) Using Gene Expression Programing (GEP) and Group Method of Data Handling (GMDH)

Earthquake is one of the natural disasters that has always influenced human life. It is not currently possible to predict exactly when and where an earthquake will occur, nor how large it will be. It is also impossible to prevent an earthquake. However, by designing seismic-resistant structures, the amount of financial losses and casualties can be reduced. This resistant design requires the use of earthquake risk analysis. By using the earthquake risk analysis, it will be possible to estimate the parameters of the strong ground motion, including acceleration, velocity, and displacement in each area. Estimating the parameters of strong ground motion will be possible just by obtaining the appropriate attenuation relationship. The aim of this paper is to present an appropriate attenuation relationship to estimate the horizontal component of the possible occurrence of peak ground acceleration in each region. Two methods were used to calculate attenuation relationship: gene expression programing (GEP) and group method of data handling (GMDH). In the first step, an up-to-date and comprehensive catalog consisting of 1,185 earthquake records that occurred around the world has been prepared. In the next step, the parameters of magnitude, hypocentral distance, and shear wave velocity of these records have been used as variables of the attenuation relationship. Then, the fitness function (f) was determined, and attenuation relationships were calculated using GEP and GMDH. The amount of fitness function (f) was obtained 766.12 from 1,000 in the GEP method and 767.77 from 1,000 in the GMDH method. The values of the fitness function, residuals and comparison plots showed a high-agreement between “the values predicted by the attenuation relationships” and “the actual values observed in the earthquakes.” Finally, according to the results of this research, it can be said that the use of GEP and GMDH methods has provided better results than the other similar researches. Also, the use of up-to-date records makes the results of this research more reliable than the previous researches.

Response of Geologic Units to The Ground Parameters of Tarutung Earthquake 2022 Mw 5.8 : A Preliminary Study

On 1st October 2022, a moderate crustal earthquake with Mw 5.8 occurred in the northen part of Tarutung region and was strongly felt by the local peoples and followed by massive damages. The occurrence of the Tarutung earthquake was firstly assumed in the southern part of the Renun fault then updated to the pull-apart system of Toru fault. Here, we concern about the ground paramaters that generated a massive shaking and connect with the recent geologic units beneath the Tarutung region. The peak ground acceleration (PGA) and peak ground velocity (PGV) clearly show an amplification case may arise in the basin formation that consists of Alluvium Formation whereas the attenuation to the west and east part with Martimbang and Sipoholon Caldera Formation. The PGV was ranging at 0 – 10 cm/s and the PGA was ranging at 0% – 16% gal which are suitable with the intensity range at 3 – 6 MMI. The PGV, PGA and intensity relationship show a possibility of the building damage percentage is up to 80% and 50% of the surrounding area may potentially experience a complete damage. The pseudo-spectral acceleration (PSV) at 0.3s, 1.0s, and 3.0s also show a potential damage that can be found at low-moderate building structure with 8% - 16% gal. The ground parameters show an empirical relationship that can be used to assess the possible of geologic units in the Tarutung region. Furthermore, our result benefits can be applied to support the mitigation program and environmental planning in Tarutung region in the near future.

Influences of regional site condition and grid size on seismic damage assessment of water distribution systems

In this study, the influences of regional site condition and grid size on the seismic damage assessment of water distribution systems (WDSs) are quantitatively examined. A water distribution system, termed M-WDS, is employed as the demonstrated system. With an assumed strike-slip linear fault in the vicinity of M-WDS, a number of spatially correlated peak ground velocity fields are realized for scenario earthquakes for each combination of grid size and regional site-condition parameter. Seismic damage analyses are then conducted for both scenario-based and probabilistic-based earthquake cases. Comparative results under scenario earthquakes indicate that increasing grid size notably increases the uncertainty of the seismic damage estimates of M-WDS, and such grid-size influence is more pronounced for more heterogeneous regional site conditions. It is also found that using a large grid size results in overestimated risk-based assessment for the probabilistic damage estimates of M-WDS, and the annual rates of exceeding large numbers of damaged pipelines are higher as the regional site conditions become more homogeneous. Additional analyses are conducted to investigate such influences on the seismic damage assessment of large-city scale WDSs. The ratio of the grid area to the whole WDS area being 0.02 is generally recommended for choosing an appropriate grid size for WDSs with different scales. A further reduced grid size is recommended for study areas exhibiting heterogeneous regional site conditions.

Permissible Scale Factors for Various Intensity Measures in Aftershock Ground Motion Scaling

This manuscript investigates the bias introduced by scaling aftershock ground motions when evaluating the performance of structures subjected to earthquake sequences. The study focuses on different hysteretic behaviors exhibited by structures and selects eight intensity measures as scale indicators. A benchmark database comprising 274 recorded mainshock–aftershock ground motions is utilized for analysis. The findings reveal that scaling aftershock records using intensity measures such as SI (seismic intensity), PGV (peak ground velocity), IC (Arias intensity), and Sa (spectral acceleration) relative to mainshock records effectively controls the mean bias within 30% throughout the entire period range, given a maximum scale factor of 10.0. However, it is observed that the additional damage in systems exhibiting un-degrading hysteretic behavior is more significantly affected by aftershock ground motion scaling compared to systems with degrading hysteretic behavior. Furthermore, scaling aftershock ground motions upwards using relative Sa tends to overestimate the additional damage incurred by structures. These results emphasize the importance of considering the specific hysteretic behavior of structures when applying aftershock ground motion scaling, as well as selecting appropriate intensity measures for accurate evaluation of structural performance.

Seismic fragility analysis of water supply pipelines retrofitted with corrosion-protection liner buried in non-uniform site

The corrosion-protection liner (CPL) technology consists of installing flexible plastic liners with anchoring studs inside existing pipelines and subsequently filling cement mortar to the gap between the waterproof liner and the pipeline. With the excellent chemical resistance, impermeability and fast construction speed, CPL provides an economical and environmentally friendly alternative for pipeline rehabilitation without large-scale excavation. However, the seismic performance of water supply pipelines after being retrofitted with CPL has not been well studied yet. In this study, a series of full-scale quasi-static experiments were firstly conducted on ductile-iron push-on joints before and after reinforcement with CPL to investigate the nonlinear behavior of the joints under longitudinal load and transverse bending. Simplified numerical models of straight pipelines with joints before and after retrofitting in the non-uniform site were then developed in the OpenSees platform, and incremental dynamic analysis (IDA) were performed with consideration of nonlinear soil-pipeline interaction. Twenty-eight pairs of ground motions with the peak ground velocities (PGV) collectively scaled from 200 mm/s to 3000 mm/s were used as inputs. Seismic fragility curves of the pipelines before and after retrofitting were developed with respect to the optimum intensity measure, PGV. It can be seen from the experimental results that the longitudinal load and bending moment capacity of the push-on joint increased about 400% and 20% after CPL reinforcement, respectively, and the joint opening and rotation decreased about 20% and 18% after retrofitting. Numerical results show that the CPL reinforced pipelines exhibit better seismic performance and CPL effectively reduces the failure probability of segmented pipelines under earthquake ground excitations.

Offshore near-fault pulse-like ground motions: An insight into the DONET1 seafloor ground motions from the 2016 Mw6.0 Off-Mie earthquake in Japan

Offshore near-fault ground motions were obtained by the DONET1 seafloor seismic network during the 2016 Off-Mie Mw6.0 earthquake that occurred in the Nankai Trough of Japan. These data provide an opportunity for exploring the characteristics of offshore near-fault ground motions, especially pulse-like ground motions. A comparison of the offshore and onshore near-fault ground motions indicates that the recorded offshore spectral acceleration (SA) in the period of 0.5–5.0 s and peak ground velocity (PGV) for this earthquake are higher than those of the onshore values, and the observed maximum spectral value (βmax) of the offshore near-fault ground motions in this event is underestimated by the design spectra in the seismic codes of China, the United States, and Japan. Based on the Hilbert-Huang transform method, eight offshore pulse-like ground motion records are identified and extracted in the Off-Mie earthquake. The primary analysis indicates that the pulse-like ground motion may be caused by the directivity effect and the radiation pattern. Comparing the pulse parameters, time-frequency parameters, and response spectra of offshore and onshore pulse-like ground motions, the findings demonstrate that within the context of this earthquake event, approximately half of the offshore pulse amplitude (Vp) exceeds the predicted values of onshore models; the low-frequency components of offshore pulse-like ground motions of this event are more pronounced, constituting a larger portion of the total ground motion energy; offshore pulse-like ground motions exhibit a tendency to possess higher maximum instantaneous energy (Einst) compared to onshore pulse-like ground motions with similar rupture distances. Moreover, the βmax of offshore pulse-like ground motions is found to be greater than that of onshore pulse-like ground motions in medium to long periods (>0.5 s). The identified and characteristic recognition of offshore near fault pulse-like ground motion revealed by this earthquake event raises new concerns about seismic design for offshore engineering.

Updating proxy-based site amplification map with in-situ data in Osaka, Japan: A Bayesian scheme based on uncertainty projected mapping

Site amplification maps are mostly proxy-based. Often due to the absence of in-situ data at the regional or local scale, a high level of confidence cannot be assigned to the site amplifications. It has often been observed that the in-situ amplifications differ from proxy-based estimates. So, whenever new in-situ data are made available, it is necessary to update the proxy-based estimates. Bayesian frameworks are recently gaining attention as model updating schemes. This study proposes a Bayesian scheme for updating proxy-based maps with in-situ data. This scheme is based on uncertainty projected mapping (UPM), where the significance of local in-situ data variability determines the posterior estimates. The study area is in Osaka, Japan, where discrepancies in proxy-based estimates and observed ground motions were documented during the 2018 Northern Osaka earthquake. Dense borehole data from the Kansai Geo-informatics Network are available in this area. Peak ground velocity (PGV) site amplification evaluations from this dense borehole network are used as likelihoods to update the prior proxy-based Japan seismic hazard information system (J-SHIS) site amplification map. As a result, the posterior map shows updated site amplification estimates which better represent the in-situ data. The updated site amplification map is then used to investigate the role of site amplification in explaining the building damage during the 2018 Northern Osaka earthquake.

Seismic vulnerability of shallow tunnels subjected to far-field long-period ground motions

Extensive documentation and research have highlighted the destructive impact of near-field earthquakes on underground structures, while the effects of far-field earthquakes remain relatively less explored. In regions such as Bangkok and Singapore, where active seismic faults are located at a significant distance, the influence of far-field motions on tunnels tends to be ignored. However, far-field earthquakes are generally less destructive than near-field motions due to their low peak ground acceleration, peak ground velocity, and Arias intensity, resulting in lower energy. Conversely, far-field earthquakes tend to have a longer duration than near-field and a higher probability of containing long-period waves, which can lead to higher responses in the low-frequency region of the response spectrum. When these far-field ground motions are applied to thick layers of soft natural clays, a common geological feature in Bangkok, they can undergo significant amplification in the long-period range, resulting in large soil displacements and shear strains. Consequently, this induces significant forces in the tunnel lining comparable to those generated by near-field earthquakes. This paper presents a comprehensive study of this rarely investigated topic, using advanced numerical simulations to analyse the seismic behaviour of a shallow circular tunnel in Bangkok soft clays subjected to long-period earthquakes. The results show that far-field earthquakes have the potential to generate forces in the tunnel lining that are equally destructive as those induced by near-field motions. Therefore, these far-field effects should be accounted for in the seismic design of tunnels.

ANN-based ground motion model for Turkey using stochastic simulation of earthquakes

SUMMARY Turkey is characterized by a high level of seismic activity attributed to its complex tectonic structure. The country has a dense network to record earthquake ground motions; however, to study previous earthquakes and to account for potential future ones, ground motion simulations are required. Ground motion simulation techniques offer an alternative means of generating region-specific time-series data for locations with limited seismic networks or regions with seismic data gaps, facilitating the study of potential catastrophic earthquakes. In this research, a local ground motion model (GMM) for Turkey is developed using region-specific simulated records, thus constructing a homogeneous data set. The simulations employ the stochastic finite-fault approach and utilize validated input-model parameters in distinct regions, namely Afyon, Erzincan, Duzce, Istanbul and Van. To overcome the limitations of linear regression-based models, artificial neural network is used to establish the form of equations and coefficients. The predictive input parameters encompass fault mechanism (FM), focal depth (FD), moment magnitude (Mw), Joyner and Boore distance (RJB) and average shear wave velocity in the top 30 m (Vs30). The data set comprises 7359 records with Mw ranging between 5.0 and 7.5 and RJB ranging from 0 to 272 km. The results are presented in terms of spectral ordinates within the period range of 0.03–2.0 s, as well as peak ground acceleration and peak ground velocity. The quantification of the GMM uncertainty is achieved through the analysis of residuals, enabling insights into inter- and intra-event uncertainties. The simulation results and the effectiveness of the model are verified by comparing the predicted values of ground motion parameters with the observed values recorded during previous events in the region. The results demonstrate the efficacy of the proposed model in simulating physical phenomena.

Random forest-based multi-hazard loss estimation using hypothetical data at seismic and tsunami monitoring networks

This article presents a novel approach to estimate multi-hazard loss in a post-event situation, resulting from cascading earthquake and tsunami events with machine learning for the first time. The proposed methodology combines the power of random forest (RF) with data that are simulated at seismic and tsunami monitoring locations. The RF model is well-suited for predicting highly nonlinear multi-hazard loss because of its nonparametric regression and ensemble learning capabilities. The study targets the cities of Iwanuma and Onagawa in Tohoku, Japan, where seismic and tsunami monitoring networks have been deployed. To encompass a diverse range of future multi-hazard loss estimation, an RF model is constructed based on 4000 simulated earthquake events with peak ground velocity and tsunami wave amplitude captured at ground-motion monitoring sites and offshore wave monitoring sensors, respectively. The incorporation of 10 ground-motion monitoring sites and five offshore wave monitoring sensors significantly enhances the model’s forecasting power, leading to a notable 60% decrease in mean squared error and 20% increase in the R 2 value compared to scenarios where no monitoring sensors are utilized. By harnessing the capabilities of RF and leveraging detailed sensing data, RF achieves R 2 values over 90%, which can contribute to enhanced disaster risk management.

Recognition of the causative fault of the 2017 MW 4.9 Malard (Tehran, Iran) earthquake from directivity analysis of the recorded ground motions

On December 20, 2017, a light shallow earthquake (Mw 4.9) with a purely strike-slip mechanism occurred on a hidden unknown fault, 30 km west of the city of Tehran. The purpose of this study is to determine the causative fault plane based on the directivity effect that was observed during this shallow crustal depth earthquake, referred to as the Malard earthquake. This was achieved by using data from 96 seismic and accelerometer stations, and employing a variety of methods.For the analysis of the directivity effect, we employed methods including empirical Green's function deconvolution in the frequency domain, inversion of corrected ground motions based on empirical models, and comparison of relative peak ground acceleration and velocity between the mainshock and the largest aftershock. All approaches indicate that the Malard earthquake occurred on a previously unknown fault with a strike of 71°, a steep southward dip, and a confirmed left-lateral strike-slip mechanism, as evidenced by the analysis of aftershock distribution. The earthquake exhibited a strong directivity effect, with rupture propagating unilaterally from the hypocenter to the southwest at a velocity of 2.5 km/s.In addition to enhancing our understanding of active earthquake sources in the densely populated areas of Iran, the findings of this study will also contribute to future earthquake risk assessments in the Tehran region. However, it's important to note that Tehran was situated in the backward zone of the Malard earthquake rupture, where the least ground motion was recorded. Future earthquakes on this fault may exhibit different propagation patterns, toward the city. The determination of a preferred propagation direction can only be achieved probabilistically through the study of a substantial number of earthquakes in the region. The absence of recorded ground motion data will lead to significant uncertainty in predicting the propagation direction of future earthquakes, which must be taken into consideration during hazard analysis.

The Seismic Behavior of Buildings with Flat Slab Systems under Near-Fault Ground Motions

It is well known that structural displacement or ductility demands of structures subjected to near-fault ground motions are generally greater than ordinary ground motions. Therefore, the effect of earthquake records in the near region on the seismic behavior of structures has been widely studied in the last decades. Peak ground acceleration (PGA) is an important key parameter, which determines structural behavior. However, structural behavior depends on the distance of the structure to the fault zone, the ratio of peak ground velocity (PGV) to peak ground acceleration, the velocity pulse duration of ground motion, and the natural period of the structure. In this study, the seismic behavior of buildings with flat slab systems was investigated under near-fault ground motions. Linear time history analysis was performed for a 30-storey building designed according to TBEC-2018 using SAP 2000 finite element analysis software. Results were compared with the behavior of the building with a solid slab system. It is concluded that the ratio of PGV/PGA is very effective on the flat slab systems.

The impact of induced earthquakes on mental health: evidence from the Dutch Lifelines Cohort Study

Abstract Background A growing body of literature demonstrates that exposure to events, such as natural disasters, accidents, or adverse life events, may increase the risk of physical and psychological distress. Despite this understanding, little is known about the health consequences of consistent exposure to human-made crises. To address this issue, we examine the long-term health effects of mining-induced earthquakes in the Northern Netherlands and study the heterogeneity of the effect across socioeconomic status (SES). Methods Large-scale individual health data is from the Dutch Lifelines biobank and cohort study with 148,700 participants from the Northern Netherlands. Earthquake data is from Royal Netherlands Meteorological Institute. The main health outcomes are housing-related stress, depression, anxiety, and self-assessed health. The key independent variable is accumulated peak ground velocity. We use an individual-level fixed effects model to assess the health effects of induced earthquakes by controlling individual heterogeneity, especially migration preference. Further, we add the interaction terms of accumulated PGV and education level into the regression model to analyze the different effects of earthquakes across SES. Results We find an association between living in high-exposure areas and housing-related stress. The results also show that for each additional noticeable earthquake (PGV>0.5 cm/s), the probability of getting anxiety increases by 1.04% on average. Moreover, the number of noticeable earthquakes (PGV>0.5 cm/s) has an adverse impact on self-assessed health. After adding the interaction terms, considerable health effects disparities were observed between SES, with the highest health effects of earthquakes in the lowest SES groups. Conclusions Our results indicate that the long-run effects of sequences of small shocks are more significant than previously believed. The low SES group was the most vulnerable population to induced earthquakes. Key messages • This paper aims to estimate the causal effects of mining-induced earthquakes on health by employing large-scale panel data from the Lifelines biobank and cohort study in the Northern Netherlands. • Our findings suggest that exposure to repeated earthquakes has a negative effect on housing-related stress, anxiety, and self-rated health.

Significance of Pulse-Like Ground Motions and Directivity Effects in Moderate Earthquakes: The Example of the Mw 6.1 Gölyaka-Düzce Earthquake on 23 November 2022

ABSTRACT The 1400 km long North Anatolian Fault Zone in Türkiye runs through numerous densely populated regions, including the city of Düzce that was recently hit by an Mw 6.1 earthquake on 23 November 2022. This was the first moderate event in the region after the devastating Mw 7.2 earthquake in 1999, which cost the lives of over 700 people. Despite its moderate size, the earthquake caused unexpected severe damage to a significant number of buildings, as reported by local institutions (Disaster and Emergency Management Presidency, AFAD). It is well established that ground motions in the near field can lead to increased damage due to near-field domain effects, such as ground-motion pulses and directivity effects (i.e., when the site is aligned with rupture propagation). We examine potential near-field effects using the strong ground motion database of AFAD-Turkish Accelerometric Database and Analysis Systems. To achieve this, we first analyze the behavior of the ground-motion intensities in terms of their spatial distribution and observe higher peak ground velocity than expected by ground-motion models in spatially constrained azimuthal ranges. Furthermore, we find that the majority of the near-fault recordings contain velocity pulses that are primary concentrated on the fault-parallel component. This outcome questions the widely accepted understanding from the previous studies, which mainly suggested that impulsive ground motions that are associated with directivity effects primarily occur on the fault-normal component of large-magnitude events.

Utilising Artificial Neural Networks for Assessing Seismic Demands of Buckling Restrained Braces Due to Pulse-like Motions

Buckling restrained brace frames (BRBFs) exhibit exceptional lateral stiffness, load-bearing capacity, and energy dissipation properties, rendering them a highly promising choice for regions susceptible to seismic activity. The precise and expeditious prediction of seismic demands on BRBFs is a crucial and challenging task. In this paper, the potential of artificial neural networks (ANNs) to predict the seismic demands of BRBFs is explored. The study presents the characteristics and modelling of prototype BRBFs with different numbers of stories and material properties, utilising the OpenSees software (Version 2.5.0) for numerical simulations. The seismic performance of the BRBFs is evaluated using 91 near-fault pulse-like ground motions, and the maximum inter-storey drift ratio (MIDR) and global drift ratio (GDR) are recorded as a measure of seismic demand. ANNs are then trained to predict the MIDR and GDR of the selected prototypes. The model’s performance is assessed by analysing the residuals and error metrics and then comparing the trend of the results with the real dataset. Feature selection is utilised to decrease the complexity of the problem, with spectral acceleration at the fundamental period (T) of the structure (Sa), peak ground acceleration (PGA), peak ground velocity (PGV), and T being the primary factors impacting seismic demand estimation. The findings demonstrate the effectiveness of the proposed ANN approach in accurately predicting the seismic demands of BRBFs.