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25 pages, 9969 KB

Open AccessArticle

Multi-Hazard Exposure Prioritization with Time-Varying Population: Integrating Seismic Amplification Susceptibility and Flood Hazards in Seoul

by Youngsuk Lee and Jihye Kim

Appl. Sci. 2026, 16(7), 3513; https://doi.org/10.3390/app16073513 - 3 Apr 2026

Viewed by 171

Abstract

Urban disaster management frequently relies on isolated single-hazard assessments and static census data. This conventional approach systematically obscures the highly dynamic, time-varying nature of population exposure to co-located environmental hazards. This study develops an observation-based, time-adaptive multi-hazard exposure prioritization framework to quantify these [...] Read more.

Urban disaster management frequently relies on isolated single-hazard assessments and static census data. This conventional approach systematically obscures the highly dynamic, time-varying nature of population exposure to co-located environmental hazards. This study develops an observation-based, time-adaptive multi-hazard exposure prioritization framework to quantify these spatiotemporal variations. We integrate seismic amplification susceptibility, derived from shear-wave velocity estimates, and empirical pluvial flooding footprints with hourly dynamic living population data at a 250 m grid resolution in Seoul, South Korea. Results indicate that multi-hazard integration refines spatial prioritization, with 11% of high-priority areas diverging from single-hazard models, primarily driven by highly amplifiable alluvial deposits. Furthermore, dynamic living population data revealed clear diurnal exposure shifts. Business districts exhibited a daytime-to-nighttime exposure ratio of 3.35, whereas residential areas showed an inverse ratio of 0.69, demonstrating that identical physical conditions generate markedly different exposure patterns depending on the daily urban rhythm. Based on these temporal dynamics, we classified high-priority zones into Persistent (79.4%), Day-peak (10.3%), and Night-peak (10.3%) transition types. These findings suggest that urban exposure must be managed as a time-varying attribute rather than a static feature. The proposed classification supports targeted mitigation: structural improvements for Persistent areas, dynamic crowd management for Day-peak zones, and localized alerts for Night-peak zones. Driven by globally accessible mobile data, this framework provides a transferable foundation for exposure-informed urban resilience planning across diverse metropolitan environments. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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40 pages, 8586 KB

Open AccessArticle

An Integrated Geotechnical Ground–HAZUS Framework for Urban Seismic Vulnerability Assessment in Seoul, Korea

by Han-Saem Kim and Ju-Hyung Lee

Appl. Sci. 2026, 16(3), 1349; https://doi.org/10.3390/app16031349 - 29 Jan 2026

Viewed by 446

Abstract

This study presents an integrated framework that couples three-dimensional geotechnical ground modeling with a HAZUS-based urban seismic vulnerability assessment for Seoul, Korea. Over 63,000 boreholes, in situ seismic tests, and building inventory records were compiled into a unified relational database following rigorous multi-stage [...] Read more.

This study presents an integrated framework that couples three-dimensional geotechnical ground modeling with a HAZUS-based urban seismic vulnerability assessment for Seoul, Korea. Over 63,000 boreholes, in situ seismic tests, and building inventory records were compiled into a unified relational database following rigorous multi-stage quality control. A multi-parameter N–Vs regression model was calibrated to supplement missing shear-wave velocity (Vs) data, reducing prediction errors by more than 20% relative to conventional empirical equations. Based on the quality-controlled Vs dataset, a high-resolution three-dimensional Vs–ground model was constructed to represent subsurface heterogeneity and associated uncertainty across the metropolitan area. The building inventory, comprising approximately 700,000 structures, was standardized according to the HAZUS structural taxonomy and mapped to Korean seismic design eras, enabling a Seoul-adapted vulnerability assessment in which exposure characterization and seismic demand are localized. Site-specific ground-motion amplification and response spectra derived from the 3D ground model were used to modify the spectral acceleration input to the HAZUS fragility functions. Results reveal pronounced spatial variability in site conditions, with northern mountainous zones corresponding primarily to NEHRP Site Class B, central districts to Class C, and southern alluvial basins to Classes D–E, producing amplification differences of up to 1.7 under identical input spectral accelerations. High-risk zones such as Gangnam, Songpa, and Yeouido exhibit concentrated expected damage where thick alluvial deposits coincide with dense stocks of mid-rise reinforced-concrete buildings. Overall, the study demonstrates that integrating high-resolution 3D geotechnical ground models with HAZUS-based fragility analysis provides a physically consistent and data-driven basis for urban-scale seismic risk assessment and resilience planning. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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18 pages, 16226 KB

Open AccessArticle

Liquefaction Hazard Assessment and Mapping Across the Korean Peninsula Using Amplified Liquefaction Potential Index

by Woo-Hyun Baek and Jae-Soon Choi

Appl. Sci. 2026, 16(2), 612; https://doi.org/10.3390/app16020612 - 7 Jan 2026

Cited by 1 | Viewed by 504

Abstract

Liquefaction is a critical mechanism amplifying earthquake-induced damage, necessitating systematic hazard assessment through spatially distributed mapping. This study presents a nationwide liquefaction hazard assessment framework for South Korea, integrating site classification, liquefaction potential index (LPI) computation, and probabilistic damage evaluation. Sites across the [...] Read more.

Liquefaction is a critical mechanism amplifying earthquake-induced damage, necessitating systematic hazard assessment through spatially distributed mapping. This study presents a nationwide liquefaction hazard assessment framework for South Korea, integrating site classification, liquefaction potential index (LPI) computation, and probabilistic damage evaluation. Sites across the Korean Peninsula were stratified into five geotechnical categories (S1–S5) based on soil characteristics. LPI values were computed incorporating site-specific amplification coefficients for nine bedrock acceleration levels corresponding to seismic recurrence intervals of 500, 1000, 2400, and 4800 years per Korean seismic design specifications. Subsurface characterization utilized standard penetration test (SPT) data from 121,821 boreholes, with an R-based analytical program enabling statistical processing and spatial visualization. Damage probability assessment employed Iwasaki’s LPI severity classification across site categories. Results indicate that at 0.10 g peak ground acceleration (500-year event), four regions exhibit severe liquefaction susceptibility. This geographic footprint expands to seven regions at 0.14 g (1000-year event) and eight regions at 0.18 g. For the 2400-year design basis earthquake (0.22 g), all eight identified high-risk zones reach critical thresholds simultaneously. Site-specific analysis reveals stark contrasts in vulnerability: S2 sites demonstrate 99% very low to low damage probability, whereas S3, S4, and S5 sites face 33%, 51%, and 99% severe damage risk, respectively. This study establishes a scalable, evidence-based framework enabling efficient large-scale liquefaction hazard assessment for governmental risk management applications. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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19 pages, 8024 KB

Open AccessArticle

Earthquake Ground Motion Characteristics as a Function of a Preprocessing Procedure

by Bongseok Ryu, Soyoung Bang and Dongyoup Kwak

Appl. Sci. 2025, 15(23), 12453; https://doi.org/10.3390/app152312453 - 24 Nov 2025

Viewed by 911

Abstract

To enable the engineering application of earthquake ground motion records, this study establishes a standardized preprocessing procedure and systematically analyzes how each preprocessing step affects the characteristics of the ground motion data. Due to recent expansion of seismic networks in South Korea, low- [...] Read more.

To enable the engineering application of earthquake ground motion records, this study establishes a standardized preprocessing procedure and systematically analyzes how each preprocessing step affects the characteristics of the ground motion data. Due to recent expansion of seismic networks in South Korea, low- to mid-amplitude seismic ground motions become abundant. However, raw ground motion recordings contain instrument responses and ambient noise and are often affected by baseline drift, which leads to divergence in the integrated displacement time histories. Therefore, reliable use of these records in engineering analysis requires a comprehensive preprocessing procedure that includes instrument response correction, signal windowing, filtering, and baseline correction. In this study, we performed a sensitivity analysis on ground motion data recorded in South Korea to quantitatively assess how key preprocessing parameters influence ground motion characteristics. Based on the findings, a standardized preprocessing workflow is proposed to support the effective use of ground motion records in site response analysis, dynamic structural analysis, and seismic hazard assessments. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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16 pages, 9022 KB

Open AccessArticle

Influence of Ground Conditions on Vibration Propagation and Response Under Accidental Impact Loads

by Jae-Kwang Ahn, Yong-Gook Lee, Sang-Rae Lee, Mintaek Yoo, Cheolwoo Park and Jae Sang Moon

Appl. Sci. 2025, 15(22), 12068; https://doi.org/10.3390/app152212068 - 13 Nov 2025

Viewed by 985

Abstract

Vibrations of unknown origin can cause fear and confusion when their sources are unrecognized. In modern construction environments, such vibrations may result not only from earthquakes but also from accidental impacts during industrial operations. However, due to the absence of established safety standards, [...] Read more.

Vibrations of unknown origin can cause fear and confusion when their sources are unrecognized. In modern construction environments, such vibrations may result not only from earthquakes but also from accidental impacts during industrial operations. However, due to the absence of established safety standards, evaluating and compensating for the effects of short-duration, high-intensity vibrations has remained difficult. This study investigates the characteristics of ground motions induced by accidental impact loads through finite element-based numerical simulations. The analyses identify key factors that control vibration propagation under various subsurface conditions. The results show that an impact load produces a single impulsive motion dominated by a vertical component, which decays exponentially with time. The amplitude of vibration increases with drop height and girder mass, confirming the relationship between potential energy and vibration intensity. The attenuation of peak particle velocity (PPV) follows a logarithmic pattern with distance, and the variation in attenuation depends on soil thickness and the presence of a weathered-rock layer. These results demonstrate that both the magnitude of impact and the ground composition control the amplitude, frequency content, and duration of impact-induced vibrations, providing a basis for assessing unmonitored accidental events. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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19 pages, 4815 KB

Open AccessArticle

High-Resolution Seismic Susceptibility Assessment Integrating Vulnerability and Exposure Indicators: Application to Seoul

by Youngsuk Lee and Jin-Kwon Yoo

Appl. Sci. 2025, 15(22), 11942; https://doi.org/10.3390/app152211942 - 10 Nov 2025

Cited by 2 | Viewed by 867

Abstract

Seismic risk assessment in megacities requires a high-resolution spatial framework that can capture the intrinsic heterogeneity of local geology, building distribution, and population characteristics beyond conventional administrative boundaries. This study develops a hazard-independent seismic susceptibility framework for the Seoul Metropolitan Area, a megacity [...] Read more.

Seismic risk assessment in megacities requires a high-resolution spatial framework that can capture the intrinsic heterogeneity of local geology, building distribution, and population characteristics beyond conventional administrative boundaries. This study develops a hazard-independent seismic susceptibility framework for the Seoul Metropolitan Area, a megacity of approximately 9.5 million residents (as of 2024), where historical and instrumental earthquake records are limited. The proposed framework integrates nine standardized indicators across geotechnical, structural, and social domains within a vulnerability–exposure model, analyzed on a 250 m grid—approximately 300 times finer than district-level assessments. Domain-specific indices and the integrated Seismic Susceptibility Index (SSI) were derived using Analytic Hierarchy Process (AHP)-based weighting to quantify the relative importance of indicators. Results show a highly concentrated spatial pattern of susceptibility: only 2.2% of Seoul (229 grids, 14.3 km²) falls within the high-to-very-high categories, primarily in northern and southwestern residential zones characterized by soft soils, aging buildings, and vulnerable populations. The proposed framework supports targeted risk-reduction strategies by providing a practical basis for pre-disaster decision-making and efficient allocation of mitigation resources in data-scarce urban environments. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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19 pages, 5474 KB

Open AccessArticle

Evaluation of Railway Bridge Responses to Blast Vibrations and Earthquake Ground Motions Based on Numerical Simulation

by Jae Sang Moon, Mintaek Yoo, Sunnie Haam and Yu Seong Lee

Appl. Sci. 2025, 15(21), 11479; https://doi.org/10.3390/app152111479 - 27 Oct 2025

Viewed by 657

Abstract

In this study, the dynamic responses of railway bridges generated by both blast motions and earthquakes are comparatively studied. A numerical model of a three-span continuous prestressed concrete (PSC) box girder bridge, a representative type of railway structure, was developed to investigate its [...] Read more.

In this study, the dynamic responses of railway bridges generated by both blast motions and earthquakes are comparatively studied. A numerical model of a three-span continuous prestressed concrete (PSC) box girder bridge, a representative type of railway structure, was developed to investigate its dynamic performance. Dynamic analyses were conducted under two blast-induced ground motions and four earthquake ground motions, and the structural responses at the girder top were employed to evaluate the dynamic behavior of the railway bridge. The results indicate that the blast-induced bridge responses are relatively small compared to the earthquake-induced bridge responses (2–3% of the bridge response). This implies that the blast vibration limit provided in the Korean standard manual could be excessively conservative when applied to the railway bridges. Also, the results show that the blast vibration limit should be revisited, with a consideration of different structures and conditions. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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24 pages, 14889 KB

Open AccessArticle

A New Ground-Motion Prediction Model for Shallow Crustal Earthquakes in Türkiye

by Ulubey Çeken, Fadime Sertçelik and Abdullah İçen

Appl. Sci. 2025, 15(7), 3442; https://doi.org/10.3390/app15073442 - 21 Mar 2025

Cited by 2 | Viewed by 1870

Abstract

The recent expansion of the strong-motion observation network, along with the increase in data obtained during major earthquakes and efforts to create consistent metadata for source, path, and site effects for both old and new records, has significantly improved the quality of data [...] Read more.

The recent expansion of the strong-motion observation network, along with the increase in data obtained during major earthquakes and efforts to create consistent metadata for source, path, and site effects for both old and new records, has significantly improved the quality of data and the level of modeling in Türkiye. The mainshock and aftershock records of the 6 February 2023 Kahramanmaraş earthquake doublet (M_W 7.8 and 7.7), which are among the most destructive earthquakes in world history, constitute an up-to-date and important data source for this study. In this study, we present new ground-motion prediction models (GMPMs) for shallow crustal earthquakes using strong-motion data recorded in Türkiye. Our GMPMs are calibrated using 20,173 strong-motion records from 1565 shallow crustal earthquakes with depths of less than 35 km that occurred in Türkiye and its vicinity between 1976 and 2023. Our model is valid for magnitudes ranging from 4.0 to 7.8 (M_W), and for the time-averaged 30 m shear wave velocity (V_S₃₀) values of 975 stations, which ranged from 131 to 1862 m/s. In the analyses performed, using the recently developed site amplification model, we calculated the model coefficients using the mixed-effects regression algorithms used by the GMPM developers. Additionally, a heteroscedastic model was created for aleatory variability as a function of M_W. The closest distance to the surface projection of the fault plane (R_JB) is between 0 and 350 km. Using the metadata prepared according to these criteria, we derived up-to-date ground-motion prediction models for horizontal-component peak ground velocity (PGV), peak ground acceleration (PGA), and 5% damped pseudo-spectral acceleration (PSA) response spectra, at 36 periods ranging from 0.01 to 10 s. The variability in the predictions was decomposed into within-event, between-event, and site-to-site deviations to determine the total standard deviations (σ). Compared to previous models, the proposed GMPMs were developed using a much richer database with recent major earthquakes, and the consistent estimates and lower residuals in the comparisons support the reliability of the models. Full article

(This article belongs to the Special Issue Soil Dynamics and Earthquake Engineering)

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