Earthquake Risk Research Articles

Seismic Risk Assessment for the City of Sofia, Bulgaria

An earthquake is the most destructive natural phenomenon, with its sudden onset and rapid spread impacting large areas. Among the various geohazards, seismic ones dominate in terms of their social and economic effects on human life and the urban environment. In the present study, a deterministic earthquake ground motion scenario for the city of Sofia (the capital of Bulgaria) is presented. The earthquake risk posed to Sofia is quantified by considering the city’s seismic context, which contributes to its hazard and risk. The assessment of seismic hazards and the generation of earthquake scenarios make up the first step of seismic risk evaluations, as risk reduction strategies can only be developed with a better understanding of these threats. Risk assessment and its associated management comprise the most effective approach to estimating the impact of seismic hazards on the city of Sofia, which exhibits high seismic activity. Our findings provide a basis for local governments to review their susceptibility and preparedness. The consideration of earthquake scenarios in the creation of policies for seismic risk reduction will allow us to focus on the prevention of earthquake effects rather than on the activities following these disasters.

Analysis of deformation evolution characteristics of the northern Lajishan fault before the Jishishan MS6.2 earthquake based on GNSS observations

A MS6.2 earthquake struck Jishishan Country in Gansu Province on 18 December 2023. The earthquake occurred on the eastern branch of the Northern Lajishan fault (NLJSF) which has never experienced such a violent seismic event in recorded history. In this study, multiple periods of GNSS campaign observation data and continuous observation data are collected to reveal the crustal deformation evolution characteristics of the eastern branch of the NLJSF before the earthquake, focusing on the dynamic behavior of the causative fault, regional strain parameter features, and the variation of GNSS baselines across the NLJSF. Velocity field data show that the differential movement on both sides of the fault zone before the earthquake accumulated energy for the occurrence of the earthquake. Cross-fault profile analyses indicate a noticeable weakening of horizontal shortening on both fault flanks, suggesting a nearing fault lockup. The baseline time series and strain parameter time series results both show that the study area is mainly NEE-trending compression deformation. In addition, before the earthquake, multiple baseline results and strain parameter time series deviated from the linear trend and gradually flattened, indicating a strain accumulation in the study area. The overall crustal deformation evolution shows a relatively high earthquake risk before the Lajishan earthquake.

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

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

Earthquake disaster-induced urban policies: paradoxes and challenges in Turkey

ABSTRACT Over 92% of Turkey’s land is exposed to earthquake risk: from historical earthquakes to the recent Kahramanmaras disaster, earthquakes created dramatic consequences. Consequently, there is a pressing need for urban policies aimed at mitigating earthquake risk and implementing a nation-wide urban transformation. In this regard, the central government enacted Law 6306, the ‘Law on Transformation of Areas under Disaster Risk’, in 2012. This paper analyses earthquake-oriented restructuring policies that are authorised by this law. It is argued that the law introduces a new set of risks due to its centralised, discretionary, non-transparent and non-participatory approach. While the constant threat of earthquake still endangers the lives of millions, it also creates an opportunity to exploit the urban space for speculative interest.

KAJIAN RENCANA TATA RUANG WILAYAH BERDASARKAN RISIKO BENCANA GEMPA BUMI DI KOTA JAYAPURA

A study has been conducted on the typology of earthquake disaster-prone areas in the city of Jayapura and the suitability of Regional Spatial Planning (RTRW) for land use capacity in the city of Jayapura. The study onearthquake disaster-prone area typology aims to determine the distribution of stability levels of the area againstthe risk of earthquakes. This study employs a weighting matrix method for area stability based on the Minister ofPublic Works Regulation No. 21 of 2007 concerning Guidelines for Spatial Planning of Volcanic Eruption andEarthquake-Prone Areas (Department of Public Works, 2007). The research results indicate that the final score forthe city of Jayapura is between 30 - 45, which falls into all stability categories: stable and less stable. Thepercentage of area for each category is 97.81% for Stable Type A, 1.91% for Stable Type B, and 0.28% for LessStable Type C. The typology of earthquake disaster-prone areas in Jayapura based on stability scores falls intocategories A, B, and C. The study on the suitability of the Regional Spatial Planning (RTRW) for 2013-2033 with the land usecapacity in Jayapura was assessed by scoring data on land capacity and land use, followed by an overlay analysis.This resulted in a land capacity suitable for development of 57,039.39 hectares, or about 60.48% of the study area,while approximately 37,272.96 hectares, or around 39.52%, were deemed unsuitable.

Earthquake Anxiety & Self-Compassion Skill: A Study on Their Demographic Differences & Relationships

This study aims at analyzing the relationship between earthquake anxiety and self-compassion skill, while evaluating gender differences. Data from a total of 273 participants were used to assess the earthquake anxiety and self-compassion skill levels of the participants. The findings indicate that the earthquake anxiety is higher among women but the self-compassion skill is more apparent among men. In the reliability analysis performed for the earthquake anxiety and self-compassion skill measurements; Crohnbach’s alpha coefficients were used. Accordingly, the coefficients were calculated as (0.98) for earthquake anxiety scale and (0.84) for self-compassion scale. It was revealed that both scales had high reliability coefficients. Correlation analysis results indicate that the individuals with high earthquake anxiety have lower self-compassion skill. In addition, it was observed that the earthquake anxiety increased according to the risk magnitude, that is to say, it was found that the earthquake anxiety were more apparent in the individuals residing in the areas at high earthquake risk. The regression model established between self-compassion scale and earthquake anxiety scale were also found significant. These findings shed a light to the further studies to be performed to better understand the complex relationship between earthquake anxiety and self-compassion skill. This study makes an important contribution to the fact that psychological support services and crisis intervention programs can reach to the individuals more efficiently, taking the relationship between earthquake anxiety and self-compassion skill.

Investigation of local soil properties of Erzurum province (Eastern Türkiye) by Horizontal/Vertical Spectral ratio method

Erzurum province is a basin developed under the effect of strike-slip faults in the Eastern Anatolia region. Erzurum province is generally influenced by the left strike-slip Erzurum Fault Zone, the left- strike-slip Aşkale fault, and the Başköy-Kandilli reverse fault. It is also located approximately 80 km from the Karlıova joint, which is the intersection of the North Anatolian and East Anatolian Faults. When the earthquakes of the instrumental and historical periods are analyzed, it is seen that many damaging earthquakes of medium to large magnitude have occurred in Erzurum province. Erzurum basin is generally covered with old alluvium at the edges of the plains, while the flat areas in the central parts are covered with new alluvium. Determination of local soil properties in regions with high earthquake hazard plays an important role in reducing earthquake risks. For this purpose, single station microtremor measurements were applied at 25 sites in Palandöken and Yakutiye districts of Erzurum province. The measurements were taken for at least 30 minutes and evaluated according to the Horizontal/Vertical Spectral Ratio method. As a result of the analysis, the dominant period, H/V ratio and vulnerability index (Kg) values of the measurement points were calculated. The period values obtained vary between 0.15 s and 3.7 s, while the H/V ratios vary between 2.2 and 8.5. The Kg value obtained using these parameters is defined as the vulnerability of the soil. It is concluded that high period, high H/V and high Kg values are obtained in areas with recent alluvium and multidisciplinary analyses should be performed in soil investigations in these regions.

Dam impoundment near active faults in areas with high seismic potential: Case studies from Bisri and Mseilha dams, Lebanon

Reservoir induced seismicity is caused by stress changes due to the impoundment of water behind dams. In seismically active areas, the presence of critically located active faults makes the impoundment of water behind dams a seismic safety risk. Dam projects in Lebanon have become a soaring example of complacency and negligence that has overlooked the concerns for seismic safety raised over the projects and their high potential of inducing seismicity. In this paper, we use 2D and 3D fully coupled poroelastic modeling to assess the risk of dam impoundment on seismogenic faults located near dam sites in Lebanon. The coulomb failure stresses are calculated along the faults, and their variations are observed in relation to changes in pore pressures and normal stresses. In addition, the expected maximum earthquake magnitudes are computed along those faults. Our results show a high risk for reservoir induced seismicity on faults that are either underneath the reservoir or hydraulically connected to a fault beneath the reservoir. Consequently, the studied dams would present a serious hazard of induced seismicity in time where the region is already at high risk of destructive earthquakes after the catastrophic seismic events that struck Turkey and Syria on 6 February 2023 on the Eastern Anatolian Fault, which is connected to the Dead Sea Transform Fault that passes through Lebanon.

Rupture process of the 2019 Mw 6.8 Davao Del Sur earthquake, Philippines from geodetic and seismic data

Because of its complex tectonic setting, the Philippines experiences vigorous seismic activity. On December 15, 2019, an Mw 6.8 earthquake struck Davao del Sur, the Philippines, severely damaging infrastructure and adversely affecting the population. In this study, we used Interferometry Synthetic Aperture Radar (InSAR) and teleseismic broadband data to explore the earthquake’s source parameters, rupture process, and tectonic characteristics through a Bayesian modeling approach and Coulomb stress analysis. An analysis of InSAR suggested that the mainshock occurred on an NW–SE oriented single plane within the Cotabato fault system, with the Makilala-Malungon fault being the causative fault. The Joint inversion revealed that the rupture initiated in the middle crust (depth: approximately 16.5 km), exhibiting a blind, left-lateral strike-slip fault rupture propagation with minimal reverse slip and no surface rupture. The slip was concentrated in a distinct asperity spanning a depth of 3–24 km, with the peak slip reaching approximately 1.8 m. The source time function of this event indicated a single pulse with a total source duration of approximately 17 s. The static stress drop value was low, which may be related to the brittle condition of the crust. Coulomb stress changes calculations suggested earthquake risk in the future.

Advanced documentation technologies for people-centred preparedness and re-construction in Bela, India

PurposeDespite the recurrence of earthquakes, responses are usually triggered afterwards, lacking mitigation strategies to diminish risks. Damaged dwellings cannot be immediately reinforced to continue inhabitation, generating disruption. Repairs are usually costly, as large numbers of affected constructions make damage assessment difficult, and post-earthquake reconstruction programmes often lack a heritage-specific approach. This research seeks to address these issues through a methodology based on high-end documentation technologies applied to built heritage and local community engagement.Design/methodology/approach The methodology proposed combines different recording tools to capture social and built environment data, such as interviews, mapping, drone capture, photography and 3D laser scanning, in the pilot case study of Bela, a historical settlement in the seismic region of Kutch in Gujarat, India, affected by the 2001 Bhuj earthquake. This paper particularly discusses aspects of community engagement around data capture and representation processes.FindingsThe introduction of advanced documentation technologies can help speed up the process of damage assessment, analyse social aspects that are key to a respectful re-construction, and enhance community engagement through visual representations, which are relevant to social acceptance and understanding towards a meaningful introduction and sustained use in earthquake risk management.Research limitations/implicationsThe methodology proposed can inform similar cases in seismic areas and enhance engagement, helping to develop a sense of awareness in the community regarding the need for preparedness in the face of earthquakes. However, there are technical challenges in using advanced recording technologies in terms of equipment accessibility, skills, knowledge and future uses of the data. Social and cultural aspects, such as caste and gender divisions, also implied disparity in accessing the data and relating it to the research team, bringing forward the need to tailor public engagement to achieve inclusivity. Practical implicationsThis study has practical implications. The most relevant one is how the process of carrying out the research served as a way to raise awareness for future seismic events. In this regard, local academic institutions and non-governmental organisations (NGOs) are critical mediators in reaching the community in greater depth, from which to bridge to external and/or governmental agencies based on existing links and trust.Social implicationsThis study also shows social implications. As a case study-based research, the link developed with the local community will help coordinate actions in case an earthquake occurs and increase cohesion within the community towards a joint aim, in this case, to reduce the risk of disasters due to seismic events.Originality/valueThis paper accounts for a novel approach to documenting buildings in heritage settlements prone to earthquakes that uses the digital record as (1) a basis to assess and intervene in the built environment and better understand how it supports the local community’s ways of living and maintaining buildings; and (2) a platform for local engagement and agency in planning and re-construction as a post-disaster mitigation measure.

The same but different: A cross‐country comparison of national earthquake policies and societal perspectives of seismic risk in Israel and Switzerland

AbstractNational earthquake policies aim to mitigate earthquake risk by minimizing the potential damage to lives, property, and infrastructure and by preparing the population to carry out recommended behaviors when an earthquake is felt or a warning is heard. In this research, we compare two earthquake‐prone countries, Israel and Switzerland, to examine if and how their policies to mitigate seismic risk differ, and how citizens react to the national earthquake policies in terms of their perceived risk of earthquakes and their preparedness. We examine and compare four national‐level earthquake policy components—risk assessment, mitigation regulation, early warning system, and risk communication with the public. We find that centralized national‐level policy in Israel, which includes regulated building codes, a nationwide early warning system, and national awareness campaigns, does lead to higher levels of reported awareness and preparedness. Similarly, in high‐risk cantons in Switzerland, which apply these policies (except for the warning system), citizens were also more prepared than in low‐risk cantons. However, given learning from both countries' policies, we suggest that earthquake policies should include collaboration with local authorities and the population through a more decentralized and localized approach, which includes drills, training, and information dissemination.

The Earthquake Risk Model of Switzerland, ERM-CH23

The Earthquake Risk Model of Switzerland, ERM-CH23

Multiple faces of labour market segmentation within the Turkish construction industry

Abstract This study explores labour market segmentation within the Turkish construction industry, in a developing country context characterised by refugee influxes and heightened earthquake risks. We apply statistical and regression analyses using 2002–2020 Household Labour Force Survey data to explore segmentation with a specific focus on payment, job type and social security enrolment. The findings reveal a segmented labour market where the progress in regular, permanent and registered employment in the 2000s failed to encompass most construction workers. Lower wages, and temporary and unregistered work are more common among the youngest and oldest workers, those with poor education and qualification levels, immigrants, and those employed by micro enterprises. The construction industry lags behind both manufacturing and services in terms of registered and permanent employment rates and average wages. The prevalence of workers in elementary jobs with little education highlights the ongoing challenge of ensuring a highly skilled workforce, while reconstruction activities in earthquake-prone zones and the demand for urban transformation in Türkiye are increasing. We argue that improvements in working conditions constitute an urgent restructuring component in the sector for elevating the status of construction jobs, addressing the shortage of skilled labour and ensuring a high-quality building stock that upholds the right to a secure life in Türkiye.

Experimental and numerical investigation on cyclic behavior of beam‑to‑column connection with a lateral steel slit damper

The objective of this research is to propose an innovative slit damper that can be installed in beam-to-column connections of steel structures as a fuse and energy dissipation device. These devices can be used as an effective and inexpensive way to mitigate earthquake risks to structures, and they can also improve the seismic behavior of building structures. Specifically, structures equipped with these devices can withstand more drift while their main members remain in an elastic state, thereby reducing the cost of rebuilding structures after earthquakes. In this study, four specimens were experimentally tested. Three beam-to-column connections were equipped with the proposed damper, and the fourth one was used as a reference sample. This damper can be referred to as a lateral slit damper (LSD). The test results show that all samples have stable and complete hysteresis curves without pinching. So, the LSDs can improve the ductility of beam-to-column connections. The test results showed that the innovative system can enhance the strength and ductility of the T-stub connection around 73 % and 21 %, respectively. To validate the LSD experimental findings, finite element models were employed for calibration. A numerical study using ABAQUS examined the system's hysteretic behavior under cyclic loading, revealing excellent agreement between the numerical and experimental results. Finally, the proposed LSDs demonstrate exceptional ductility, strength, effective hysteretic curves, and post-earthquake reparability. These qualities position it as a promising and practical damper for mitigating seismic risks in engineering structures.

Rationalizing geosociality: Mexican expert earthquake risk reduction practice

Rationalizing geosociality: Mexican expert earthquake risk reduction practice

NUMERICAL ERROR METHOD TO DETERMINE THE EFFICIENCY OF REDUCING VIBRATIONS DUE TO EARTHQUAKE LOADS ON BUILDINGS USING FLUID VISCOUS DAMPER

According to The Indonesian Earthquake Map, Padang City in West Sumatra is in Earthquake zone 6. This indicates that Padang City is very vulnerable to earthquakes. Meanwhile, developments in the construction of high buildings also continue to show progress all the time. The main problem that is often faced is the issue of structural damage due to earthquakes. Efforts are needed in earthquake engineering on buildings so that collapse can be minimized. The earthquake damping system used is FVD (Fluid Viscous Dampers) with different types. The Type-A damper is FVD-750 kN and the Type-B damper is FVD-1000 kN, and without using a damper. This research aims to analyze the efficiency of reducing earthquake loads such as floor displacement and vibration period of an 18-story building structure 18 meters high from the base.The analysis method used is a numerical method by calculating earthquake load reduction based on numerical error analysis from the two types of dampers used on structures without using dampers. Building planning refers to SNI 1727-2013, SNI 1726-2019, and SNI 2847-2019, and is assisted by ETABS software. Based on SNI 1726-2019, earthquake risk category II, soft soil condition type (SE), earthquake acceleration response value SDS = 0.745g and SD1 = 0.784g are obtained. The earthquake load used is a dynamic load, taking into account that the condition of the building is irregular. Based on the results of the analysis, it was found that the displacement between floors using the Type-AFVD Damper could reduce the displacement by up to 45.72% and with the Type-B FVD Damper it could reduce the displacement by up to 92.72%. Meanwhile, the period of vibration natural using a Type-A FVD Damper can be reduced by up to 12.34% and using a Type-B FVD Damper can be reduced by up to 33.21%.

ANALYSIS OF POST-DISASTER CITY STRUCTURE CHANGES IN INDONESIA: STUDY CASE MATARAM CITY OF LOMBOK (NTB)

Purpose: Research has been carried out on identifying the risk of earthquake disasters in the West Nusa Tenggara. Methodology: Region based on 3 factors: the earthquake hazard factor, namely the maximum acceleration of ground vibrations (Peak Ground Acceleration = PGA), the vulnerability factor, namely the population density of the sub-district, and the resilience factor, namely the HDI (Human Development Index) of the sub-district. in West Nusa Tenggara Province. The PGA value was calculated using the Fukushima and Tanaka attenuation function with earthquake parameter data from 1970 – 2014 with criteria of magnitude ≥ 4.5mB, depth ≤ 60 km and epicenter in the range 7.5O – 12.5O LS and 115O-120O BT, while calculating the earthquake disaster risk index uses the AHP (Analytical Hierarchy Process) method. Results and Conclusion: From the calculation results, it was found that the areas with the highest level of earthquake disaster risk were the southern part of Dompu Regency, Mataram City, Bima City, northern Bima Regency, while the lowest were West Sumbawa Regency and southern Sumbawa Regency.

Seismicity and fractal analysis in Aswan region, southern Egypt

Seismic activity in Aswan is influenced by the complex interactions of tectonic plates, the accumulation of stress, and the presence of geological fault systems. It revealed that epicenters are well distributed along four fault segments in a conjugate pattern, indicating a prominent E-W compressional stress. This research aims to explore the characteristics of seismicity and seismotectonics, with a focus on assessing their implications for risk reduction and disaster management in this densely populated region. A data review from the Egyptian National Seismological Network (ENSN) identified 464 earthquakes occurred between 2000 and 2021, with local magnitudes ranging from 0.3 to 4.4, and depths up to 25 km. The calculated Gutenberg-Richter b-value is approximately 0.87 ± 0.05, indicating a gradual stress accumulation. The current analysis shows a more consistent level of moderate seismic activity, unlike previous studies in Aswan region that reported a wide range of b-values from 0.554 to 1.07. This suggests that while earlier research captured a wider range of seismic behaviors, recent data indicates a stabilization in earthquake frequency and intensity. Additionally, the fractal dimension (Dc) calculated at 1.57 ± 0.04 shows an intermediate level of complexity and reflecting a clustering pattern of earthquakes. The variations in the b-value with different magnitudes and depths signify the involvement of active smaller faults, responsible for earthquakes up to magnitude 2.2, which then transition to fractured zones inducing earthquakes up to magnitude 2.5. This transition is followed by a decline in seismic activity, indicating regions that are potentially more likely to experience larger earthquakes. Moreover, stress disparities at various depths contribute to smaller earthquakes within the 5–10 km depth range. Return period analysis suggests that the earthquakes of magnitude 3.7 or higher are expected to occur approximately once every decade in Aswan. These findings are of utmost importance for earthquake risk reduction, hazard assessment, and the sustainable development of Aswan area.

Managing Induced Seismicity Risks From Enhanced Geothermal Systems: A Good Practice Guideline

AbstractGeothermal energy is a green source of power that could play an important role in climate‐conscious energy portfolios; enhanced geothermal systems (EGS) have the potential to scale up exploitation of thermal resources. During hydraulic fracturing, fluids injected under high‐pressure cause the rock mass to fail, stimulating fractures that improve fluid connectivity. However, this increase of pore fluid pressure can also reactivate pre‐existing fault systems, potentially inducing earthquakes of significant size. Induced earthquakes are a significant concern for EGS operations. In some cases, ground shaking nuisance, building damages, or injuries have spurred the early termination of projects (e.g., Basel, Pohang). On the other hand, EGS operations at Soultz‐sous‐Forêts (France), Helsinki (Finland), Blue Mountain (Nevada, USA), and Utah FORGE (USA) have adequately managed induced earthquake risks. The success of an EGS operation depends on economical reservoir enhancements, while maintaining acceptable seismic risk levels. This requires state‐of‐the‐art seismic risk management. This article reviews domains of seismology, earthquake engineering, risk management, and communication. We then synthesize “good practice” recommendations for evaluating, mitigating, and communicating the risk of induced seismicity. We advocate for a modular approach. Recommendations are provided for key technical aspects including (a) a seismic risk management framework, (b) seismic risk pre‐screening, (c) comprehensive seismic hazard and risk evaluation, (d) traffic light protocol designs, (e) seismic monitoring implementation, and (f) step‐by‐step communication plans. Our recommendations adhere to regulatory best practices, to ensure their general applicability. Our guidelines provide a template for effective earthquake risk management and future research directions.

Buckling contributes to both coseismic uplift and long-term fold growth in active fold-thrust belts

Understanding the interplay among fault slip, fold growth, and earthquakes is crucial for assessing earthquake risk and deciphering the relationship between long-term and short-term deformation in fold-thrust belts. While fault-related folding theories have dominated previous studies, the role of the buckling process—characterized by bed-parallel contraction—in seismicity and fold development has been underreported. Herein, we attempt to address this issue through an examination of the 28 March 2019 M5.0 Mangya earthquake in the Shizigou anticline, western Qaidam Basin (northern Tibetan Plateau), based on 3-D seismic imaging data, interferometric synthetic aperture radar (InSAR) analysis, and borehole loggings. We show that this earthquake was not caused by slip along known faults, but by interbed slip due to buckling in the limb of the anticline, demonstrating for the first time that buckling could result in moderate earthquakes. The buckling process not only leads to coseismic uplift deviating from the folding crest induced by slip on the underlying fault, but also modulates the long-term geometric growth of the Shizigou anticline. Our findings underscore the significance of the buckling process in contributing to short-term coseismic slip and long-term fold growth in active fold-thrust belts.