Earthquake Events Research Articles

Artificial intelligence for assessing the planets' positions as a precursor to earthquake events

Questions about interconnection possibilities between planets’ positions and seismic events on the earth have emerged recently in TV channels, social media, etc. In this study, an Artificial Neural Network (ANN) and Random Forest Regression (RFR) are used to predict the number of earthquakes that can occur on Earth, depending on the Earth’s position relative to other planets and solar positions. Our new integration dataset contains 9809 observations and nine features firstly from the global earthquake archive, which is an authoritative layer by Esri, and secondly from the accurate data web portal “theskylive.com.”.The results obtained from RFR and ANN prove the partial influence of planets positions on sesimic activity on the earth. In other words, quantitatively through the ANN that gets an accuracy of 68.27 %, MAE of 5.36, MSE of 52.78, RMSE of 7.26, R-Squared of 0.65, and also through the RFR that gets an accuracy of 65.06 %, MAE of 5.60, MSE of 58.21, RMSE of 7.63, R-Squared of 0.67, prove the partial influence on one hand. Qualitatively through the curve of the training phase of the ANN, which is a decreasing and convex function, reinforces the aforementioned proof on the other hand. For these reasons, it can be deduced that there is a possible connection between tectonic stress triggers and the positions of the planets in the solar system. Our dataset was uploaded to the github(https://github.com/mouddentarik/Earthquake01.) as well as the code will be publicly available at the github(https://github.com/mouddentarik/PythonCode_Earthquakes-.) to share our results.

A method for analysing the dynamic response of a CWSLT under rainfall and earthquake

ABSTRACT In typical engineering applications of loess tunnels, rainfall has a significant influence on the loess mass of tunnels. In order to explore the influence of rainfall seepage on the tunnel dynamic response, this paper takes the common curved wall section loess tunnel (CWSLT) as an example, employs the finite element method (FEM), considers the effects of earthquakes and rainfall seepage, the CWSLT models are established and the shaking table test was carried out, the variation laws of stress, displacement, and acceleration of the CWSLT under different buried depths, rainfall amounts and earthquake types (near-field with pulse, near-field without pulse) are studied. The results show that with the increase of rainfall, the lining stress increases and the tensile stress in the middle of the inverted arch of the tunnel lining structure increases; Under different earthquakes, the maximum stress of the tunnel appears at the arch foot and the midpoint of the inverted arch; With the increase of buried depth, the settlement displacement of loess tunnel increases gradually. The above research results have important guiding significance for the design and construction of loess tunnels.

Seismicity zoning at Coso geothermal field and stress changes from fluid production and migration

The Coso geothermal field is a major geothermal power production site in the western United States. It has been observed that low-magnitude seismic events (M < 3.71) are unevenly distributed in three distinct zones, namely, nearfield (<3 km), midfield (3–6 km), and farfield (> 6 km) from the Coso geothermal plant. These zones exhibit distinct changes in earthquake location before and during geothermal production episodes that began in 1986. After 1986, the midfield region of the main flank experiences a significantly lower seismicity rate than the surrounding areas before production episodes. During 2014–2019, the farfield earthquakes cluster in the eastern and western parts of the greater Coso area, which is discernably different from how those pre-production earthquake events were distributed along the conjugate NW-SE and SW-NW trending structures across the main flank. Here, we analyze the stage of stress with finite-element-based poroelastic simulations to illustrate how the spatiotemporal evolution of the seismicity is associated with the pattern of stress perturbations caused by fluid migration amid the operations of geothermal power plants. Generally, ∼70% of co-production seismicity is found in zones of increased Coulomb stress between 2014 and 2019 at >99% confidence. Meanwhile, the midfield zone of seismic paucity overlaps with the zone of decreasing pore-fluid pressure. Overall, the results provide a physical explanation of how decadal geothermal operations at Coso have perturbed stress-field changes and contributed to the evolving characteristic seismic pattern, shedding insights into assessing the seismic hazard in other geothermal settings.

The role of liquefaction in the evolution of shallow submarine canyon heads from a geotechnical perspective: A case study of the Garrucha Canyon (SE Mediterranean)

This work aims to establish the role of liquefaction in a shallow submarine environment defined by a canyon head reaching the coast. The study area is the Garrucha submarine canyon head, which is located in the western Mediterranean Sea.The potential of liquefaction is approached empirically by two methods in parallel, undrained cyclic direct simple shear (UCDSS) test and piezocone penetration test (CPTu) analyses. For both approaches, considering the regional earthquake records, a cyclic load linked to Mw ≤ 6.5 earthquake events or a maximum ground surface acceleration amax of 0.25 g is considered.The sediment samples analysed are nonplastic sands with low silt/clay contents and can be defined as liquefiable. Geotechnical analysis reveals a high probability of triggering liquefaction in this kind of sediment at depths greater than 3 m below the seafloor. CPTu records are used to assess and improve the liquefaction model for the study area by defining 3 different stratigraphic configurations or liquefiable conditions: uniformly liquefiable, interbedded liquifiable and nonliquefiable.This work highlights the importance of liquefaction—a process normally underestimated in submarine environments—in the downslope transport of sediment from the upper part of a canyon and, more generally, in canyon head evolution with different potential morphosedimentary consequences.

Inhomogeneity effects on earthquake fault events.

We present a detailed analysis of the dynamical behavior of an inhomogeneous Burridge-Knopoff model, a simplified mechanical model of an earthquake. Regardless of the size of seismic faults, a soil element rarely has a continuous appearance. Instead, their surfaces have complex structures. Thus, the model we suggest keeps the full Newtonian dynamics with inertial effects of the original model, while incorporating the inhomogeneities of seismic fault surfaces in stick-slip friction force that depends on the local structure of the contact surfaces as shown in recent experiments. The numerical results of the proposed model show that the cluster size and the moment distributions of earthquake events are in agreement with the Gutenberg-Richter law without introducing any relaxation mechanism. The exponent of the power-law size distribution we obtain falls within a realistic range of value without fine tuning any parameter. On the other hand, we show that the size distribution of both localized and delocalized events obeys a power law in contrast to the homogeneous case. Thus, no crossover behavior between small and large events occurs.

Seismic design parameters of double-layer diamatic domes

The effect of past earthquakes (e.g., the 1995 Kobe and 2016 Kumamoto earthquakes) on the space structures revealed the fact that the assumption of the invulnerability of these structures is incorrect despite their light self-weight and high degree of redundancy, and space structures may suffer severe damage during strong ground motions. Therefore, special attention should be paid to the design of this type of structure in high seismic-risk regions. Nevertheless, the existing seismic design codes have not provided the seismic design parameters (i.e., the seismic response modification factors), including the behavior factor, R, and the displacement amplification factor, Cd for space structures. This research aims to extract the seismic design parameters of double-layer diamatic domes (DLDDs) to answer the challenges that structural engineers face in the design of this type of structure. For this purpose, 16 DLDD models with different rise-to-span ratios (RSRs) and span lengths were considered. After designing the models and performing the nonlinear time history analysis using the simultaneous effect of the three transitional components of ground motions, the target displacement at the control node was determined. Then, the pushover analysis was carried out to derive the capacity curve of the structures and calculate the seismic response modification factors in both horizontal and vertical directions. The results indicate that the domes with RSRs of 1/7 and 1/5 should be designed such that they remain in the elastic state in the horizontal direction. Then, with the growth of RSR, the value of R increases and reaches 1.792. Finally, equations were presented in this study for the period, behavior factor, and displacement amplification factor of DLDD structures in both horizontal and vertical directions using the nonlinear regression analysis.

Cascade processes of induced and triggered earthquakes-Case study in the Weiyuan shale gas development area in Sichuan Basin, China

Identifying accurate seismogenic faults is critical for studying the mechanisms of induced earthquakes. On February 24th and 25th, 2019, three moderate earthquakes with magnitudes of MS 4.7, MS 4.3, and MS 4.9 occurred successively in the shale gas development area of Weiyuan, China. We utilized high-resolution three-dimensional (3D) seismic data to identify two pre-existing faults (F1 and F2) that were responsible for the three moderate earthquakes. InSAR data were used to validate the rationality of the two seismogenic faults. Furthermore, we analyzed the impact of fluid diffusion on fault F1 near the fracturing well and calculated the Coulomb failure stress (CFS) generated on fault F2 by the MS 4.7 and MS 4.3 earthquakes to analyze the interactions between these events. The results indicated that fluid diffusion caused by hydrofracturing induced the MS 4.3 and MS 4.7 earthquakes on F1. The static Coulomb stress changes from these two earthquakes subsequently triggered the larger MS 4.9 earthquake on F2. This study provides a case of a cascading process in which induced earthquake events triggered a more distant and higher-magnitude earthquake. This triggering scenario reminds us that earthquake-to-earthquake interactions may be more hazardous than a “typical” inducing mechanism and challenges current risk management practices.

Seismic analysis of Islamic Egyptian minarets through 3D scanning and dynamic simulation

Recently, Egypt had seismic activity. These seismic events have affected the stability of minarets, especially historical ones. Weight is one of the minaret's main stability factors. The main objective of the current research is to perform a three-dimensional (3D) assessment of an existing minaret, determine its accurate spatial model, document its current condition, examine its stability in the event of earthquakes, and identify the requisite measures to safeguard the minaret from any potential damage. The masonry to construct the minaret was used by extracting and examining specimens of this substance to determine its physical characteristics. The current work created three-dimensional models of the Abou-Ghanam El-Bialy minaret using a terrestrial laser scanner (TLS) to document its current condition, as well as minaret was subjected to a free vibration analysis using 3D finite element modeling. Finally, the minaret's seismic behavior was assessed utilizing mode forms, base responses, and normal stresses. The surveying method effectively documented the Minarets' existing case. The 3D seismic analysis showed that the minaret responded dynamically to earthquake loading, with mode shapes, base reactions, and normal stresses being crucial characteristics. Based on these data, we may suggest procedures to protect the minaret during seismic events.

Acceleration waveform reproduction control of hypergravity centrifugal shaking table based on data driven iterative learning control and two-degree-of-freedom control

The hypergravity centrifugal shaking table (HCST) is the most effective means for studying the disaster effects of rock and soil earthquakes, and the accurate control of acceleration waveform recurrence is the critical problem. This paper compares the dynamic characteristics of the normal gravity shaking table (NGST) and the HCST, highlighting the latter’s particularities, and analyzes the limitations of the existing control strategy. Meanwhile, a hypergravity unidirectional airborne shaking table (HUAST) is designed, and a data-driven iterative learning control and two-degree-of-freedom control-based acceleration waveform reproduction strategy is proposed and experimentally verified.

Dynamic responses of steep bedding slope-tunnel system under coupled rainfall-seismicity: Shaking table test

The coupling effects of rainfall, earthquake, and complex topographic and geological conditions complicate the dynamic responses and disasters of slope-tunnel systems. For this, the large-scale shaking table tests were carried out to explore the dynamic responses of steep bedding slope-tunnel system under the coupling effect of rainfall and earthquake. Results show that the slope surface and elevation amplification effect exhibit pronounced nonlinear change caused by the tunnel and weak interlayers. When seismic wave propagates to tunnels, the weak interlayers and rock intersecting areas present complex wave field distribution characteristics. The dynamic responses of the slope are influenced by the frequency, amplitude, and direction of seismic waves. The acceleration amplification coefficient initially rises and then falls as increasing seismic frequency, peaking at 20 Hz. Additionally, the seismic damage process of slope is categorized into elastic (2-3 m/s2), elastoplastic (4-5 m/s2) and plastic damage stages (≥ 6.5m/s2). In elastic stage, ΔMPGA (ratio of acceleration amplification factor) increases with increasing seismic intensity, without obvious strain distribution change. In plastic stage, ΔMPGA begins to gradually plummet, and the strain is mainly distributed in the damaged area. The modes of seismic damage in the slope-tunnel system are mainly of tensile failure of the weak interlayer, cracking failure of tunnel lining, formation of persistent cracks on the slope crest and waist, development and outward shearing of the sliding mass, and buckling failure at the slope foot under extrusion of the upper rock body. This study can serve as a reference for predicting the failure modes of tunnel-slope system in strong seismic regions.

Seismic Vulnerability Assessment of Non-Overflow Concrete Gravity Dam Section

Abstract As the economy advances, there is a growing need for energy. Harnessing hydroelectric energy has emerged as a crucial strategy for addressing the energy crisis. To promote hydropower development, numerous tall concrete dams are either under construction or in the planning stages. These dams are frequently situated in areas with elevated water levels and face the challenge of being located in regions with high seismic intensity. An accident resulting from the failure of concrete dams can pose significant threats to both economic development and public safety. Therefore, it is of crucial importance to investigate the stability of such dams, particularly under conditions of high water levels and seismic activity. The finite element program Geostudio is being undertaken to evaluate a complete numerical analysis of the dam. In this paper, Longtan Dam has been selected as the case study for the research. This study is applied in two cases: seismic and static conditions. A two-dimensional seismic numerical analysis was carried out using the Koyna earthquake acceleration time records in 1976. The results of the FEM model concluded that the dam is unsafe under sesmic conditions. The concrete-rock interface, particularly susceptible to sliding, was identified as the most critical part of the dam, presenting the most likely failure mode. The study highlights the significance of its methodology in investigating earthquake effects on dams, prioritizing it over the achieved results. The aim is for the conclusions and recommendations to provide valuable guidance for future studies and initiatives focused on enhancing safety at hydropower dams.

The effects of earthquakes on midwifery students’ fear of death, anxiety and sense of life meaning

The effects of earthquakes on midwifery students’ fear of death, anxiety and sense of life meaning

Seismic evaluation of concrete gravity dam under the effect of far and near field earthquakes considering dam saturation

Seismic evaluation of concrete gravity dam under the effect of far and near field earthquakes considering dam saturation

Practice-oriented numerical model for seismic response of cold-formed steel-framed mid-rise buildings

Cold-formed steel (CFS) framed buildings are becoming increasingly common, notably in the high seismic regions of the United States (US). However, research to understand the seismic performance of CFS-framed buildings specifically using large-scale (building-level) specimens has begun only recently. Therefore, efforts to validate and improve numerical modeling of whole building systems have been limited due to this lack of experimental data. A recently completed experimental program, conducted at the Large High-Performance Outdoor Shake Table at the University of California, San Diego, involved earthquake testing of a full-scale 6-story CFS-framed building. The test building adopted an assembly of continuous tie-rod and built-up compression stud pack at the ends of individual shear walls to resist seismic overturning moment and uplift forces within the building. The objective of this paper is to present a practice-oriented phenomenological finite element modeling approach intended for design engineers and compare the predictions from this model against the measured seismic response of the 6-story building. The model aims to provide a robust, yet computationally efficient approach, with minimal degrees-of-freedom, while also capturing the salient features of seismic response of mid-rise CFS-framed buildings suitable for nonlinear time history analyses-based design. The building model, developed within the OpenSeesPy finite element platform, includes the shear walls and gravity walls as well as the lateral strength and stiffness contribution from exterior and interior gypsum sheathing. The continuous tie-rod system is also modeled to capture the cumulative floor displacements caused by the axial elongation in the steel rods. The effect of built-up compression stud packs on the lateral behavior of a shear wall was estimated using available experimental data and a detailed numerical model of an isolated shear wall, then subsequently incorporated in the nonlinear hysteretic material model. The numerical model captured the natural frequencies of the translation modes of the building in its undamaged state with <3% error. It also predicted the peak roof drift ratio within an error of 0.03% drift ratio under the design earthquake event. These results provide confidence in the proposed numerical modeling approach as a tool for seismic response prediction of mid-rise CFS-framed buildings with similar structural detailing features.

Assessment of the spatial and temporal dynamics of food system resilience and its response to natural hazards

Increasingly frequent natural hazards put food systems under constant stress, and there is an urgent need to improve the resilience of food systems. Quantitative assessments of food system resilience (FSR) and research on the factors that influence it are important ways to achieve this goal. In this research, we use probabilistic modeling to quantitatively assess the FSR of forty counties in the southeastern Tibetan Plateau from 2000 to 2020, and explore the spatiotemporal dynamics characteristic of FSR. The Geographically and Temporally Weighted Regression (GTWR) model is then used to examine the drivers of FSR from four dimensions: shocks, natural ecology, production conditions, and socioeconomics. The focus is on the spatial and temporal characteristics of the effects of drought, flood, wind hail, snow disaster, earthquake, and geological hazards on FSR. The results of this study highlight the spatiotemporal heterogeneity of FSR and its differential response to different hazards: 1) the assessment of FSR accurately pinpoints areas of low resilience at both spatial and temporal scales, and reveals a significant temporal phase characteristic, with most regions experiencing a notable increase in FSR since 2010; 2) High-intensity droughts and snow disasters, and frequent floods and wind hails significantly affect FSR, so it is necessary to plan targeted measures to mitigate the negative impacts of different natural hazards on food production systems. Our findings enhance the understanding of the relationship between food systems and natural hazards, and contribute to the planning of measures to safeguard food system stability and improve food system resilience to natural hazards in natural hazard-prone regions.

The Impact of Buckling Restrained Braces in Strengthening Deficient Reinforced Concrete Structures

Seismic strengthening for existing structures is a sustainable solution that is utilized to enhance building safety, reduce damages, and prevent failure in a future earthquake event. The choice of seismic strengthening techniques has to be accurate, efficient, and adjusted to make RC structures stronger in the building sector. Buckling-restrained brace (BRB) system is one of the successful strengthening strategies, that it is possible to utilize in both RC and steel structures. Therefore, this paper explores the possibility of employing buckling restrained braces in existing RC buildings and assesses the impact of different BRB bracing distributions and positions on seismic force resistance. In this work, a five-story RC building was considered, and to upgrade their performance seismic was modeled using four types of BRB systems, consisting of two types of bracing configurations with two arrangements: diagonal in the central bay, diagonal in the corner bays, chevron in the central bay, and chevron in the corner bays. To assess the efficiency of the four proposed BRB systems, firstly, the nonlinear static pushover method was conducted to investigate the lateral strength of structures. Secondly, a parametric study was undertaken using dynamic time history analysis to study various factors such as roof displacement, shear force, and roof acceleration of the original and strengthened models. The numerical study was executed using the Seismostruct software. The results and different performance levels were examined and compared. The obtained results indicate that the BRB and concrete structures can successfully work together to resist the reliability of strengthening RC structures. It was observed that the four prediction systems of the BRB models were excessively effective at upgrading the seismic resistance of the existing structure and provided significantly less damage, especially when using the chevron BRBs with the corner arrangement compared to the other models.

Simulation of January 22, 2024 Mw=7.0 Uqturpan earthquake consequences with the "Extremum" system application

This paper reports the use of intensity attenuation equations for the territory of the Northern Tien Shan by modeling the impact of a powerful destructive earthquake of January 22, 2024 in China. The relevance of the study follows from the needed reliable estimates of possible losses due to earthquakes in order to aid the decision making process for the response and the proper choice of a search and rescue strategy for the heavily affected settlements. The paper has as its goal the calibration of the Extremum system models for the territory of the Northern Tien Shan. Our study is the first to analyze the seismic intensity attenuation equations obtained by researchers at different times with a view to their applicability to near real time loss assessment for strong events occurring in the area of study. We investigate how the results of seismic attenuation modeling are affected by the ellipse compression factor k. and the source parameters of a strong event as determined by different seismological agencies in the alert mode. Computer simulation was applied to assess the possible impact of the January 22, 2024 earthquake using the "Extremum" system developed with our participation. This paper provides results of modeling the impact of the 2024 Uqturpan earthquake, as well as an assessment of the convergence achieved by calculated and observed intensities for various intensity prediction equations obtained before for China, Kyrgyzstan and adjacent areas within the Gissar-Kokshaalsky seismically active belt.

Result Comparison of Spectral Matching Between &amp;lt;i&amp;gt;Seismomatch&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Specmatch &amp;lt;/i&amp;gt;Computer Program

The earthquake ground motion, or acceleration time history, caused by an earthquake event, is an earthquake acceleration wave that can be utilized as a basis to design earthquake-resistant civil engineering buildings. The earthquake acceleration time history is needed as a basis to determine the earthquake loading for the building structure design. A time history can be developed from recorded data using spectral matching software. In this process, the response spectra of the recorded time history are matched to a specific target spectrum. The target spectrum is developed based on the Indonesian National Standard known as SNI 2012 (SNI code). The response spectra derived from this standard are referred to as the design response spectrum. These response spectra adopted by the SNI code are based on the ASCE code from the US. Two spectral matching software programs, namely Seismomatch and Specmatch, are employed for this purpose. In this study, both of software programs are utilized to match the response spectra of a time history to a predefined response spectrum. The results of the matching process indicate that Seismomatch does not produce a satisfactory match between the response spectra of the time history and the target spectrum, whereas Specmatch provides a matching result where the response spectra of the time history nearly perfectly align with the target spectrum.

Characteristic Ddepth distribution of crustal earthquakes in Southern Siberia

The key parameters of an earthquake are magnitude, epicenter coordinates, and depth. Depth often has a decisive influence on the macroseismic effect of certain earthquakes. In this regard, for example, to assess seismic risk, one should know information on the statistics of earthquake occurrence at certain depths. In this work, catalogs of continental crustal earthquakes in the Southern Siberia are analyzed. The distributions of earthquake depths are approximated by various functions. The Weibull distribution, with a maximum at 8 km, is shown to describe the depth distribution of these crustal earthquakes most accurately. When the western (Altai–Sayan) and eastern (Baikal Rift Zone) parts of the region are considered separately, the Weibull distribution is also preferable. The maximum of the distribution is found to be at 9 km for the Baikal rift zone and at 7 km for the Altai–Sayan zone.

Clutching inertial system for base-isolated liquid storage tanks: Seismic performance and optimal parameters

Liquid storage tanks (LSTs) are susceptible to significant damage during earthquake events, necessitating their continued functionality and additional protection through isolation techniques. The sloshing response and overall base shear of LSTs are critical factors, particularly in base isolated (BI) tanks. This study aims to enhance the seismic resilience of LSTs by leveraging a newly developed advanced inerter-based vibration control methodology for structures. This innovative approach integrates a supplemental clutching inertial system (CIS) with a laminated rubber isolator (LRB). Utilizing an equivalent linearization technique, the study evaluates the equivalent damping and inertance constants to account for the nonlinear behavior of the CIS. These equivalent parameters are then used to assess the stationary peak response of the isolated tank structure, which encompasses sloshing and bearing displacements, forces within the CIS and the isolator, and the total base shear. Further, the analysis employs the stationary power spectral density function (PSDF) model of earthquake excitation by Kanai-Tajimi and the performance of the inerter-based hybrid control strategy is examined by varying system parameters, such as isolation period, isolation damping, CIS inertance mass ratio, and the tank's aspect ratio (i.e., broad or slender). An optimal inertance of the CIS is identified, leading to the least overall base shear for both isolated tank configurations. The impact of these parameters inertance mass ratio of the CIS is also investigated. Subsequently, the isolated tanks are exposed to eleven near-fault (NF) and far-field (FF) real-time earthquake excitations. The study evaluates the CIS's performance as an auxiliary system during these seismic events and contrasts the outcomes with the seismic response under stochastic excitations. The results highlight the effectiveness of the advanced inerter-based hybrid control strategy in reducing the seismic response of isolated tank configurations.