Earthquake Behavior Research Articles

Energy-based damage assessment of RC frames with non-seismic beam-column joint detailing using crack image processing techniques

Quantitative post-earthquake failure safety assessment of RC framed buildings with non-ductile joints, as one of the most vulnerable structures, is presented in this study utilizing crack image analysis. For this purpose, energy-based damage indices, as the representatives of the cyclic behavior of earthquakes, are considered to quantify seismic damage. The complexity and irregularity of the crack images are quantified through the generalized fractal dimensions of the crack maps for the damaged RC beam-column joints with non-seismic details. The presented method takes advantage of a collected databank by the authors, including 255 images of surface crack maps of 56 beam-column joint specimens under cyclic loading covering a wide range of energy-based damage indices. In this study, a basic damage index based on energy dissipation along with a combined damage index based on deformation and energy dissipation are used to estimate the extent of the damage. Five symbolic regression-based predictive equations for each of the damage indices are presented based on the after-event access of the structural details. Finally, the efficiency of the proposed method is evaluated for a sample seismically damaged RC beam-column joint specimen. The post-earthquake estimation of the presented damage indices can be used for quantitative failure safety assessment of seismically damaged buildings against aftershocks, secondary numerical seismic analysis, and providing strengthening solutions for damaged RC buildings with non-seismic detailing.

Clustering of earthquakes along the Pidima-Anthia normal fault: New data from palaeoseismology and tectonic geomorphology and their significance on the earthquake's regularity and recurrence across southern Greece

The Pidima-Anthia Fault provides an opportunity to unravel the long palaeoseismic records of the Eastern Messinia Fault Zone (EMFZ) that defines the western border of the Taygetos Mtn range in Peloponnese (southern Greece). This fault zone is segmented and includes a complex system of primarily normal fault segments dipping westwards with a strike of NNW-SSE to N–S, with a traceable length from 6 to 10 km. We applied geomorphological and palaeoseismological analysis across the Pidima-Anthia Fault. The palaeoseismological trench performed across the Pidima-Anthia Fault provide evidence for five M > 6.4 earthquakes hosted on this fault and indicate an apparent slip rate of 0.23 mm/a. Geomorphologically, based on modelling the triangular facets, we estimated the slip rate as 0.28–0.44 mm/a. These data highlight that the slip rate of the fault is remarkably stable for the approximately 17 ka period, and that this duration is enough for a morphogenic active fault to create seismic landscapes. The earthquake history of the Pidima-Anthia Fault allows its comparison with six other known faults that dominate the earthquake history of southern Greece. The pattern of earthquake history in southern Greece shows clustering features (“Wallace-type” behaviour) during Late Quaternary. In particular, the Pidima-Anthia Fault's seismic history resembles with time predictable earthquakes and clustering during the Holocene. Overall, clustering appears prevalent in earthquake behaviour in southern Greece. However, the Pidima-Anthia Fault during the current period (i.e., post 1 ka A.D.)does not display cluster time-predictable behaviour and a strong earthquake can happen at any time.

Paleoearthquakes at the junction of the Tokomaru and Northern Ōhāriu faults, implications for fault interactions in the southern North Island, New Zealand

ABSTRACT The Tokomaru Fault extends along the west side of the southern North Island of New Zealand. Given the fault’s proximity to major and expanding population centres, new work was undertaken to understand its contribution to seismic hazard in the Wellington-Levin corridor. Two paleoseismic trenches excavated across the southern end of the Tokomaru Fault, close to its junction with the Northern Ōhāriu Fault, show that it and the Northern Ōhāriu Fault are more active than previously thought. Ages of the two youngest events on the Tokomaru Fault are 93–220 and 1179–1254 cal yr BP, and result in a recurrence interval of 470–2300 years. These ages agree with the two youngest events on the Ōhāriu Fault and the timing of some events on the Wellington Fault. This suggests that the Tokomaru, Northern Ōhāriu, Ōhāriu, and Wellington faults may have ruptured together in the past, have triggered earthquakes on each other, or host slip that is triggered by larger nearby earthquakes. The results of this work illustrate the importance of fault interactions in the southern North Island and show that even if faults here do not rupture together, they likely play a key role in influencing the earthquake behaviour of each other.

Linear and Nonlinear Dynamic Analysis of Reinforced Concrete Building with V Shape Steel Bracing

In this study, the RC-MRCBFs were used with V braced frame. The core objective of this examination is to understand the earthquake behavior of the RC-MRCBFs in steel V braced frames. Response spectrum analysis (RSA) is used to understand the seismic performance of the steel braced and un-braced RC frames. Total 12 steel braced RC frames and 12 un-braced frames for all 4 story, 8story, 12 stories and 16 stories are studied and observed the seismic parameter such as fundamental time period (FTP), top story displacements, inter-story drift, base shear and story stiffness of the structures. After studying the parametric study of the 4 to 16 story buildings with a linear and nonlinear analysis tool it was observed that to get the effective braced frame with expected failure mechanism, ductility, the columns should be designed such that, they resist at least 50% base shear contributions. It is observed that using the steel V bracing in the low rise to mid-rise buildings, improves the seismic behaviors of the structures. The steel bracing reduces the maximum top story displacements, drift and time period of the building and increases the seismic base shear demand, stiffness of the structures. The result shows that as increasing the base shear contribution in the columns, the drift and displacement of the story increases and base shear decreases. Key Words: Response Spectrum Analysis, displacement, Maximum storey drift, Storey shear, Storey stiffness, braced frame, RC buildings.

Stress state and waves in the lithospheric plate simulation: A 3rd generation AI architecture

Natural disasters present ongoing risks to human life and the global economy, with climate change and environmental factors exacerbating these threats. This article introduces an innovative approach to earthquake prediction and modeling, utilizing a combination of modern mathematical techniques, data-driven methodologies, and artificial intelligence (AI). By integrating the finite element method and wavelet collocation method, our approach enables the solution of complex partial differential equations involving fractional derivatives. This integration provides a more accurate prediction of earthquake behavior by leveraging AI analysis of the resulting numerical solutions.Our advanced modeling technique enables three-dimensional earthquake modeling, surpassing the limitations of traditional methods and offering unprecedented insights. The comprehensive AI approach shows great potential for improving our understanding of earthquake behavior, facilitating the design of earthquake-resistant structures, and effectively mitigating the devastating impacts of earthquakes.This research significantly contributes to the field of disaster risk reduction and offers practical applications for both researchers and practitioners. By combining mathematical rigor, data-driven insights, and the power of AI, our next-generation approach opens new avenues for enhancing our preparedness and response to seismic events.

The IDA Very Long Period and Very Broadband Networks

Abstract This article describes the rich global digital seismic data set that has been collected from 1975 to the present using a variety of instruments and progressively updated equipment and communication systems. The original IDA very long period (VLP) network operated from 1975 to 1995. The successor IRIS/IDA very broadband network began in 1986 and continues to the present. Collection of these data has supported advances in our understanding of the structure of the Earth’s deep interior and of the long wavelength heterogeneous structure of the mantle; the detailed behavior of large earthquakes; and the discovery of nontraditional seismic sources such as slow earthquakes, glaciers, and landslides. Near-real-time transmission of the data to hazard warning centers has expanded the network’s usefulness as a tool for rapid response to earthquakes, warning to communities affected by tsunamis, and for monitoring compliance with nuclear test ban treaties.

Seismic behavior of subway station in the soft clay field before and after freeze-thaw cycle

The artificial ground freezing method (AGF) is becoming increasingly popular in the construction of subway stations surrounded by soft soil foundations. However, the freeze and thaw lead to the deterioration of the soil properties, causing a huge risk to the subway station subjected to earthquakes. Based on the dynamic triaxial test, the damping ratio and dynamic shear modulus of the soft clay before and after the process of freeze-thaw were obtained. Moreover, the finite element model was conducted to investigate the earthquake behavior of the station structure in the unfrozen and freeze-thaw clay fields. The research results illustrate that there exists a significant difference in the characteristics of the ground settlement and structural displacement between these two soft clay fields subjected to the seismic wave with the peak ground acceleration (PGA) of 0.3 g. Compared with the unfrozen clay field, the surface settlement induced by the earthquake in the freeze-thaw clay field is larger. The damage degree of the subway station is more severe in the freeze-thaw clay field.

Effects of Diagonal Friction Dampers on Behavior of a Building

In this study, the effect of the friction damper location on the earthquake behavior of a building was investigated. Diagonal braced friction dampers were placed on different floors, and the changes in building behavior were examined. For this purpose, a scaled experimental building model with five floors, with a single span in the x and y directions, was used. Numerical model validation was carried out by taking into account the experimental and numerical period values obtained via the effect of free vibration. The period, peak displacement, and maximum shear force of the friction dampers, arranged in various configurations, were compared using the numerical model in conjunction with three different earthquake acceleration records. According to the investigations, the damper performance of the design changes depending on the earthquake acceleration that is affecting the building. Friction dampers located on the lower floors are more effective at reducing period, peak displacement, and floor shear forces than those located on the upper floors.

Rubber effect on metallic dampers used on the supports of steel cross members

SummaryThere are many strengthening methods made with steel cross members for strengthening the structures with inadequate earthquake behavior. This type of strengthening methods is also effective in buckling of the cross members in the behavior of the structural frames. This buckling may cause partial or complete collapse of the structure. Thus, it is quite important to prevent and limit the formation of buckling in steel crosses. At the TEC 2018, the insulation unit is defined as the elements that can exhibit flexible behavior on the horizontal direction and rigid behavior on the vertical direction under the effect of earthquake loads. The basic principle of using insulation units is that these members can dissipate energy in the carrier system. The originality of this study is to experimentally investigate the damper behavior created by using cylindrical rubber wedges, which can be easily found in the automotive industry, in combination with steel plates and bolts. In this experimental study, the contribution of seismic insulators to the structural element to be strengthened was investigated. The insulators used in this study are considered by analogy with lead‐core rubber insulators. As such seismic lead‐core rubber insulators move under the influence of lateral loads, the lead core inside makes plastic deformation, thus increasing the damping rate. In this insulator study, it is aimed to use U plates or bolts instead of lead core. While vertical loads are covered by rubber support, horizontal loads will be damped due to plastic deformation of U plates or bolts. The five types of seismic dampers were used as 10 B‐type rubber wedge mounted damper (SR), 2 U‐type steel plates damper (SP), 10 M6 steel bolted damper (SB), 2 U‐type steel plates and 10 B‐type rubber wedge mounted damper (SPR), 10 M6 steel bolted, and 10 C‐type rubber wedge mounted damper (SBR). These specimens were tested under lateral loading and constant vertical loading. The results obtained at the end of the tests shall be compared considering the strength, stiffness, and dissipated energy capacities of the specimens.

Factors influencing disaster response behavior of international tourists under the Tokyo Metropolitan Earthquake scenario

As Japan continues to become a popular global tourism destination, its vulnerability to disasters cannot be overlooked. Although the Japanese government has implemented different disaster prevention policies and practices, there is a lack of investigation into disaster response behaviors, such as information seeking, evacuation, and the factors affecting these. This study clarified the factors influencing the disaster response behavior of international tourists in the context of the anticipated Tokyo Metropolitan Earthquake scenario. A questionnaire survey was conducted, and the logistic regression model was used to understand the causative factors. The results revealed that the variable knowledge on disaster response behavior in earthquakes influences individuals' evacuation decisions, especially when people choose to follow others. These findings will be beneficial for tourism stakeholders and policymakers to establish effective tourism crisis management planning, including information provision, shelter allocation, and collaborative initiatives.

Assessing Seismic Crack Performance of Diyarbakır Çüngüş Masonry Stone Bridge Considering 2023 Kahramanmaraş, Hatay, Malatya, Gaziantep Earthquakes

Examination of the creep behavior of historical buildings and interpretation of seismic failures in historical buildings are of great importance for the safety and future of these important structures. In this study, time-dependent settlement and three-dimensional (3D) seismic analyzes of a historical stone bridge are investigated using the 3D discrete element modeling technique. For the settlement and seismic analyses, the historical single-span Çüngüş bridge which was built in the 18th century in Diyarbakır-Turkey by Ottoman Empire is used. Since Diyarbakır is in a dangerous zone according to the Turkey seismic map, the examination of this structure is very critical for the history of Turkey. The 3D model of the bridge is created using the FLAC3D program based on the finite difference method and all the stone elements in the historical bridge are modeled separately as blocks. Special interaction elements are defined between the discretely modeled stones. For settlement creep analyses, the Burger-creep material model, which was not used for the creep behavior of historical buildings in the past, is utilized. Firstly, the 500-year long-term creep behavior of the bridge is examined by considering the fix boundary condition and full reservoir condition. According to the creep analyses, it is seen that the most deformation and failure section of the bridge is the arch section. Then, for the seismic analyses of the bridge, free-field and quiet non-reflecting boundary conditions are defined in the model. Furthermore, hysteresis damping coefficients are taken into account in seismic analyzes with the help of special fish functions. 10 various earthquakes are considered for seismic analyses. According to the earthquake analyses, the earthquake behavior of the Çüngüş historical bridge is assessed by considering the full reservoir condition and it is understood that 2023 Kahramanmaraş, Hatay, Malatya, Gaziantep earthquakes significantly changed the seismic safety behavior of Çüngüş single-span historical bridge.

A study of the influence of water level fluctuations on the geodynamic situation in the natural and technical geosystem of the Dniester HPP and PSPP cascade

Purpose. Statistical information for the period from 2016 to 2021 was used to analyze seismic activity. Objective. The aim of the study is to identify the relationship between changes in water level and local seismic activity in the region. Using HPP and Psing filtering, the hypocenters of earthquakes within a radius of 30 km from the seismic station with the NDNU index were selected, and using geographic information technology tools, the hypocenters of earthquakes were compared with the geological structure of the region. Methodology. Statistical information for the period from 2016 to 2021 was used to analyze seismic activity. Using filtering, the hypocenters of earthquakes within a radius of 30 km from the seismic station with the NDNU index were selected, and using geographic information technology tools, the hypocenters of earthquakes were compared with the geological structure of the region. Results. The studies revealed a correlation between seismic events and water level fluctuations in the reservoir. The paper also established the density of episodes concentrated in the reservoir operation area, as well as the magnitude and shallow depth, indicated the probability of activation of faults located in geological layers close to the ground surface. The stresses in the soils were assessed. Using the Coulomb-Mohr theory, the ultimate stresses leading to the destruction of structural ties were calculated approximately, and the optimal modes of operation of the reservoir were determined. Originality. The research in the article allows us to more accurately assess the effect of the stress gradient in the soils on the background seismicity in the reservoir operation area. Practical significance. The practical significance of this study is understanding the effect of the stress gradient on induction earthquakes. The described method, which is based on the principles of Coulomb's law and Mohr's theory, allows us to remotely study the behavior of the material under different loading conditions. This study and the development of a geomechanical model helps to better understand and predict earthquake behavior and determine safe loading zones. This has practical implications for the design and construction of structures, as well as for risk assessment and appropriate safety measures.

High seismic velocity structures control moderate to strong induced earthquake behaviors by shale gas development

Moderate to strong earthquakes have been induced worldwide by shale gas development, however, it is still unclear what factors control their behaviors. Here we use local seismic networks to reliably determine the source attributes of dozens of M > 3 earthquakes and obtain a high-resolution shear-wave velocity model using ambient noise tomography. These earthquakes are found to occur close to the target shale formations in depth and along high seismic velocity boundaries. The magnitudes and co-seismic slip distributions of the 2018 Xingwen {M}_{{{{{{rm{L}}}}}}}5.7 and 2019 Gongxian {M}_{{{{{{rm{L}}}}}}}5.3 earthquakes are further determined jointly by seismic waveforms and InSAR data, and the co-seismic slips of these two earthquakes correlate with high seismic velocity zones along the fault planes. Thus, the distribution of high velocity zones near the target shale formations, together with the stress state modulated by hydraulic fracturing controls induced earthquake behaviors and is critical for understanding the seismic potentials of hydraulic fracturing.

Tsunami Genesis of Strike-Slip Earthquakes Revealed in the 2018 Indonesian Palu Event

The devastating tsunami after the 2018 Indonesian Sulawesi-Palu strike-slip earthquake was a surprise because strike-slip faulting was a known phenomenon of primarily lateral movement of land, while tsunamis were believed to be caused by vertical movements of seafloor or landslides. Here we demonstrated how the strike-slip faulting could have pushed waters from outside and inside the Palu Bay to form a powerful tsunami in the Palu Bay. We constructed three earthquake inversions from seismographs, satellite radar and optical imagery, and used an open-source ocean circulation model to replicate the tsunami. Our experiments revealed that: (1) the southward horizontal displacement of deeper-water slopes along the Makassar coast generated a long-wave tsunami of 40 km, propagating southward into the Palu Bay and consisting with the two distinguished tsunami-peaks in the Pantoloan tide-record, twice higher than the local resonance waves; (2) the two types of tsunamis in the Mamuju tide-record—the “early arrival” tsunami and the late larger tsunami—were originated from the outside and inside sources; and (3) the eyewitness account of the whirlpool circulation in the Palu Bay could be explained by the horizontal strike-slip forcing of the two involved tectonic plates. The east plate was largely responsible for pushing the long-wave tsunami southward that inundated the Palu City and resulted in the devastation. Our findings suggest that the tsunami’s behavior of strike-slip earthquakes is more complex than previously thought and should be considered in future tsunami early warnings.

Probabilistic prediction of post-earthquake rubble range for RC frame structures

In the post-earthquake environment, the rubble generated by the collapse of buildings will seriously affect the functionality of the transportation system, like post-disaster medical rescue, personnel evacuation, and material transport. A reasonable prediction of the distribution range of rubble from building structure collapses is vital for assessing city seismic resilience. This paper focuses on this topic from a probabilistic perspective. Twenty-two ground vibrations are the first input for reinforced concrete (RC) frame structures at different floors to simulate their collapse behavior in earthquakes. The model of rubble distribution range is then proposed to comprehensively consider the uncertainties of the ground motions and structures. The corresponding risk model is finally developed. Building heights, uncertainty associated with ground motions, the likelihood of structural collapse, and the likelihood of the interval distribution of debris are all taken into consideration by the model. The statistical analysis indicates that the proposed model can provide a reasonable prediction of the simulate results. The results can be used as a reference for city government decision-makers to develop emergency plans and as a basis for assessing the road network's capacity after an earthquake.

Earthquake Behavior of Concrete Gravity Dams During Ground Motions

Abstract The stability evaluation of the dams subjected to seismic excitations is really very complex as the earthquake response of the concrete gravity dam depends upon its connection joints with foundation rock. This study presents the seismic response of concrete gravity dams considering welded contact and friction contact and along dam-foundation rock interface. Friction contact is provided using contact elements. Two-dimensional finite element model of Oued Fodda concrete gravity dam, located in Chlef at the northwestern part of Algeria, is used for this purpose. Nonlinear analyses of dam-foundation rock system are performed using ANSYS software. The reservoir water is modeled as added mass using the Westergaard approach. The Druker-Prager model is employed in the nonlinear analysis for dam concrete. The surface-to-surface contact elements based on the Coulomb's friction law are used to describe the friction. These contact elements use a target surface and a contact surface to form a contact pair. According to this study, when the friction contact is considered in joints, sliding displacement of dam base occurs along the dam-foundation rock interface. The dam sliding along its foundation decreases the deformation response; principal stresses in the dam body and shear force at both the heel and toe of the dam.

Nonlinear Radiation Damping: A New Method for Dissipating Energy in Dynamic Earthquake Rupture Simulations

Abstract Dynamic earthquake rupture simulations are used to understand earthquake mechanics and the ground shaking that earthquakes produce. These simulations can help diagnose past earthquake behavior and are also used to generate scenarios of possible future earthquakes. Traditional dynamic rupture models generally assume elastic rock response, but this can lead to peak on-fault slip rates and ground shaking that are higher than those inferred from seismological observations. Some have approached this challenge using inelastic off-fault rock behavior to dissipate energy, but the addition of inelasticity can make it difficult to select parameters and establish suitable initial conditions, and increases the model’s complexity and computational cost. We propose a new method that works by adding a nonlinear radiation damping term to the friction law, with the surrounding rocks remaining linear elastic. Our new method results in lower peak slip rates, reduced seismic radiation, and an increasing slip-weakening critical distance with increasing rupture propagation distance, all within a linear elastic model. In addition, it is easy to implement.

Influences of across-strike heterogeneous viscosity on the earthquake cycle in a three-dimensional strike-slip fault model

Geodetic observations have shown that there exist large differences in the viscosity of the deep lithosphere across many large strike-slip faults. Heterogeneity in lithospheric viscosity structure can influence the efficiency of stress transfer and thus may have a significant effect on the earthquake cycle. Until now, how the lateral viscosity variation across strike-slip faults affects the earthquake cycles is still not well understood. Here, we investigate the effects of across-strike viscosity variation on long-term earthquake behaviors with a three-dimensional strike-slip fault model. Our model is a quasi-static model which is controlled by the slip-weakening friction law and power-law rheology. By comparing with the reference case, we find that low viscosity on one side of the fault results in a smaller rupture area but with a higher Coulomb stress drop on the ruptured fault region. In addition, low viscosity also leads to a small Coulomb stress accumulation rate. These combined effects increase the earthquake recurrence interval by approximately 10% and the earthquake moments by about 30% when the low viscosity is related to a geothermal gradient of 30 ​K/km. In addition, across-strike viscosity variation causes asymmetric interseismic ground surface deformation rate. As the viscosity contrast increases, the difference in the interseismic ground surface deformation rate between the two sides of the fault gradually increases, although the asymmetric feature is not pronounced. This asymmetry of interseismic ground deformation rate across a strike-slip fault is supposed to result in asymmetric coseismic deformation if the long-term plate motion velocity is invariant. As a result, this kind of asymmetry of interseismic deformation may influence the evaluation of potential earthquake hazards along large strike-slip faults with lateral viscosity contrast.

Nonlinear Seismic Assessment of Historical Masonry Karaz Bridge Under Different Ground Motion Records

The most significant artifacts that transfer the cultural heritage of past civilizations to the present are historical structures. Historical bridges are of great importance in terms of transportation, trade and architecture from past to present. Some of these structures have been destroyed by natural disasters or have suffered significant structural damage. Especially earthquakes cause damage to these structures. In this study, the earthquake behavior of the Historical Karaz Bridge was investigated. The structural elements of the bridge and the materials connecting the bearing elements were evaluated together with the macro modeling approach. For this purpose, a 3D finite element model of the bridge was generated and its seismic behavior under different ground motion records was investigated by nonlinear analysis. Analyzes were carried out using the ground motion records of Bingöl, Elazığ, Erzincan, Van and Gölcük, and the results were evaluated mutually. In the analysis results, the dynamic behavior of the bridge was evaluated over the distribution of displacements and stresses and the earthquake behavior was investigated.

Segmentation characteristics of deep, low-frequency tremors in Shikoku, Japan using machine learning approaches

Shikoku island, southwestern Japan lies in the western Nankai Trough and showcases along-strike segmentation of slow earthquake behavior. Whether the spatial variation of tremor behavior reflects the regional differences in structure/source properties and how much such differences can be recognized by the seismic signals themselves are two questions addressed in this paper. Taking advantage of advanced methods in recognizing and classifying signals using machine learning approaches, we attempt to answer them by conducting signal classification experiments in Shikoku. Based on the tremor catalog from 1 June 2014 to 31 March 2015, the tremors recorded in four different areas were treated as different classes and segmented into 60-s-long signals. The number of tremors in four different areas (A to D, from west to east) reached 15,000, 31,000, 10,000, and 16,000, respectively. To efficiently distinguish between tremors from different areas, we applied a k-nearest neighbor (k-NN) classifier with Fisher’s class separability criteria to select the optimal feature subset. The resulting classification performance reached more than 90% at all 12 stations. We further designed a triangle test to select the features that can better represent the differences in source properties between areas. We found that the most efficient features were associated with (1) the number of peaks in the temporal evolution of discrete Fourier transforms and (2) the energy distribution in the autocorrelation function (ACF). To match the difference in behavior revealed by the ACF, the size of the tremor zone, which mainly controls how long the seismic energy lasts in a tremor episode, was determined to be largest in Area B and smallest in Area C. The heterogeneity of the asperities in a tremor zone, which may control how spiky the tremor signals developed over time, was determined to be strong in Areas B and C. Together with previously documented variations in slow earthquake behavior in the same area, we finally propose a conceptual model that provides a better understanding of the regional differences in the tremor source properties in Shikoku, Japan.Graphical