Historical Earthquakes Research Articles

Probabilistic evaluation of earthquake-induced liquefaction using Bayesian network based on a side-by-side SPT–CPT database

In situ tests such as standard penetration test (SPT) and cone penetration test (CPT) are often conducted to evaluate the probability of earthquake-induced liquefaction. However, the models adopted have seldom attempted to utilize SPT and CPT data simultaneously. In this study, a side-by-side SPT–CPT database at historical earthquake sites is established; then, a Bayesian network model is constructed to predict the probability of soil liquefaction based on this database, with which the SPT and CPT data are utilized simultaneously. Next, comparative studies are undertaken to illustrate the superiority of the Bayesian network-based probabilistic soil liquefaction model developed over other models, in terms of six SPT- and CPT-based conventional liquefaction models in the literature and two Bayesian network-based models. It should be noted that the liquefaction sites with two in situ tests are scarce and side-by-side SPT–CPT data can be incomplete, which leads to challenges in applying the Bayesian network model developed. To address this problem, correlations between SPT and CPT data are analyzed, and these correlations are further included in the Bayesian network model; as a result, a modified Bayesian network model is reached. Finally, the influence of the proportion of missing data in the incomplete SPT–CPT data on the liquefaction prediction accuracy is discussed.

Seismic reinforcement of buildings constructed from unreinforced masonry using shotcrete

Introduction. This work mentions the existence of traditional and non-traditional methods of seismic reinforcement of buildings and structures, including buildings built from masonry and historical architectural monuments. Concrete shotcreting, or other cementbased mortar is considered as one of the methods of seismic reinforcement, which belongs to traditional methods and is regarded the most suitable in this case, since it allows seismic reinforcement of buildings constructed from unreinforced masonry, which includes many historical architectural monuments, increasing their load-bearing capacity and at the same time almost without increasing their weight.
 
 Aim. The research is intended to contribute to the seismic reinforcement of buildings, including architectural monuments, built from unreinforced masonry to withstand future seismic impacts from natural phenomena such as earthquake.
 
 Materials and methods. A review and detailed study of the seismic reinforcement method was carried out, namely shotcrete with concrete, which is a traditional method, its advantages and disadvantages, the essence of the method and the sequence of its implementation. A review of historical earthquakes in different countries and their devastating consequences for buildings constructed from unreinforced masonry was also carried out. The in-plane behavior of unreinforced masonry supports and walls under the influence of seismic lateral forces is considered.
 
 Results. The possible practical application and steps of concrete shotcrete over a metal mesh of unreinforced masonry walls for their seismic reinforcement are proposed and clearly demonstrated.
 
 Conclusions. Conclusions have been drawn about the feasibility of using shotcrete over a metal mesh for seismic reinforcement of buildings built from unreinforced masonry, which makes it possible to save the lives of people living in them in case of earthquakes.

Seismic cycle controlled by subduction geometry: novel 3-D quasi-dynamic model of Central Chile megathrust

SUMMARY Subduction earthquakes show complex spatial and temporal rupture patterns, exhibiting events of varied sizes, which rupture distinct or overlapping fault segments. Elucidating first-order controlling conditions of rupture segmentation and return periods of large earthquakes is therefore critical for seismic and tsunami hazard estimations. The Chilean subduction zone frequently hosts several Mw > 8 earthquakes, with heterogeneous recurrence rates and locations. Here, we implement 3-D quasi-dynamic rate and state frictional models to investigate the role of plate interface geometry on the distribution of interseismic coupling and coseismic ruptures in Central Chile. First, we develop synthetic-parametric models that show how dip and strike variations may increase the probabilities to produce partial seismic barriers, which tend to avoid the production of large earthquake ruptures and modulate rupture lengths. Then, we simulate the subduction seismic cycle processes on Central Chile (25°S–38°S), imposing depth-dependent frictional properties on a realistic non-planar 3-D subduction interface geometry. Similar to results obtained for synthetic-parametric models, after 5000 yr of simulation, regions with abrupt dip or strike changes increase the probabilities of stopping coseismic propagation of simulated Mw 8.0–9.0 earthquakes. Our simulated earthquake sequences on the Central Chile subduction zone delimit rupture areas that match geometrical interface features and historical earthquakes, results that point to the crucial role of fault interface geometry on seismic cycle segmentation along strike.

Recurrence Times of Large Earthquakes: Assimilating the Effect of Seismic Coupling into a Renewal Model

ABSTRACT A renewal model for estimating recurrence times of large earthquakes is presented, which allows one to assimilate data from paleo, historic, and instrumental earthquake data as well as geodetic information in a simple and efficient way using three parameters: the Richter b-value, the mean recurrence time μT of paleo and historic earthquakes, and the seismic coupling coefficient χ. The core of the model is a state variable with linear drift in time reflecting Reid’s elastic rebound theory, decorated with random fluctuations modeling small and intermediate earthquakes. Furthermore, it is assumed that a fraction between 0% and 100% of the average seismic moment is released seismically, and the remaining part corresponds to aseismic processes such as creep. The model extends former renewal models of Matthews et al. (2002) and Zöller et al. (2008). Results for different regions indicate overall good performance and thus suggest that the model provides physically motivated constraints for recurrence time estimations in contrast to the standard fitting of a few data points to an assumed distribution.

Linked and fully coupled 3D earthquake dynamic rupture and tsunami modeling for the Húsavík–Flatey Fault Zone in North Iceland

Abstract. Tsunamigenic earthquakes pose considerable risks, both economically and socially, yet earthquake and tsunami hazard assessments are typically conducted separately. Earthquakes associated with unexpected tsunamis, such as the 2018 Mw 7.5 strike-slip Sulawesi earthquake, emphasize the need to study the tsunami potential of active submarine faults in different tectonic settings. Here, we investigate physics-based scenarios combining simulations of 3D earthquake dynamic rupture and seismic wave propagation with tsunami generation and propagation. We present time-dependent modeling of one-way linked and 3D fully coupled earthquakes and tsunamis for the ∼ 100 km long Húsavík–Flatey Fault Zone (HFFZ) in North Iceland. Our analysis shows that the HFFZ has the potential to generate sizable tsunamis. The six dynamic rupture models sourcing our tsunami scenarios vary regarding hypocenter location, spatiotemporal evolution, fault slip, and fault structure complexity but coincide with historical earthquake magnitudes. Earthquake dynamic rupture scenarios on a less segmented fault system, particularly with a hypocenter location in the eastern part of the fault system, have a larger potential for local tsunami generation. Here, dynamically evolving large shallow fault slip (∼ 8 m), near-surface rake rotation (± 20∘), and significant coseismic vertical displacements of the local bathymetry (± 1 m) facilitate strike-slip faulting tsunami generation. We model tsunami crest to trough differences (total wave heights) of up to ∼ 0.9 m near the town Ólafsfjörður. In contrast, none of our scenarios endanger the town of Akureyri, which is shielded by multiple reflections within the narrow Eyjafjörður bay and by Hrísey island. We compare the modeled one-way linked tsunami waveforms with simulation results using a 3D fully coupled approach. We find good agreement in the tsunami arrival times and location of maximum tsunami heights. While seismic waves result in transient motions of the sea surface and affect the ocean response, they do not appear to contribute to tsunami generation. However, complex source effects arise in the fully coupled simulations, such as tsunami dispersion effects and the complex superposition of seismic and acoustic waves within the shallow continental shelf of North Iceland. We find that the vertical velocity amplitudes of near-source acoustic waves are unexpectedly high – larger than those corresponding to the actual tsunami – which may serve as a rapid indicator of surface dynamic rupture. Our results have important implications for understanding the tsunamigenic potential of strike-slip fault systems worldwide and the coseismic acoustic wave excitation during tsunami generation and may help to inform future tsunami early warning systems.

Seismic risk assessment for the downtown of the city of Blida, Algeria

Blida (Algeria) is characterized by a high level of seismic exposure and vulnerability due to its dense population and the presence of aging buildings. The historical earthquake that occurred in 1825, with a moment magnitude (Mw7.1), underscored the urgent need for a thorough assessment of seismic risk in the area. Here, an extensive study conducted in downtown of the city of Blida to evaluate seismic risk and its consequences is presented. Geounits 141 and 148 emerged as the most severely affected in all the simulated earthquake scenarios indicating severe damage and casualties mainly for closest earthquakes (Blida and Bounaian, both with moment magnitude Mw7.1) but also for furthest earthquakes as Mouzaia El Affroun (Mw6.6), and Hammam Melouane (Mw6.5). The sensitivity analysis demonstrated the importance of the selection of the performance point computation method (improved displacement coefficient method -IDCM, modified capacity spectrum-MADRS, and nonlinear analysis method-N2) and the choice of the ground motion prediction equation. IDCM results are less influenced by the choice of the GMPE, but they provide higher damage results expressed as a mean damage ratio. Moreover, the study estimated potential human impacts in the Blida region, highlighting varying levels of impact on different geounits under different earthquake scenarios. The study's primary findings from seismic risk assessments in the studied region highlight its high susceptibility to earthquakes and can be summarized as follows: The mean damage ratio will be 52.6% ± 1.4%, 50.9% ± 1.6%; 31.8% ± 3.4% and 21.4% ± 3.1% for the Blida, Bounaian, Mouzaia El Affroun and Hammam Melouane earthquakes respectively.

Source parameter inversion of the 2021 MW7.4 Maduo earthquake and stress transfer in the eastern Bayan Har block

In order to explore the constraint degree of GNSS and InSAR data on the Maduo earthquake under the layered earth model structure, and to understand the cause of the Maduo earthquake and the danger of the surrounding area, this paper uses D-InSAR technology to obtain the InSAR co-seismic deformation field of the Maduo earthquake on May 22,2021. Based on GNSS and InSAR data, the co-seismic slip model and fault plane stress distribution of the Maduo earthquake are jointly inverted. This paper calculates the Coulomb stress changes caused by 14 M ≥ 7 strong earthquakes co-seismic, post-seismic viscoelastic relaxation and inter-seismic tectonic stress loading of 19 fault segments in the Bayan Har block research area (96°E-106°E, 29°N-36°N) since 1900. The results show that: (1) The maximum Line Of Sight (LOS) deformation obtained based on the ascending and descending InSAR data was about 0.9 m. The maximum slip amount of GNSS + InSAR joint inversion is 4.87 m, which is located in the Dongcao Along Lake section (∼98.6°E). Combined with the stress drop distribution of the fault surface, it is found that the Maduo earthquake is dominated by strike-slip. (2) The historical strong earthquakes delayed the Maduo earthquake by nearly 103 years. The 1937 Huashixia earthquake, the 1947 Dari earthquake, the 1963 Dulan earthquake, and the 1973 Luhuo earthquake had the greatest stress unloading effect, which was equivalent to delaying the Maduo earthquake by 53 years, 21 years, 11 years, and 17 years, respectively. The cumulative Coulomb stress at the source location of the Maduo earthquake reached 0.0112 MPa. Most area of the fault sections such as the East Kunlun Fault, the Maduo-Gande Fault, the western and eastern sections of the Dari Fault, the western and eastern sections of the Qingshuihe Fault, the Ganzi-Yushu Fault, and the eastern section of the Kunlunshankou-Jiangcuo Fault are in the Coulomb stress loading area, which should be paid attention to.

Characterization of historical megathrust earthquake ruptures in Central Chile using logic tree analysis

Characterization of historical megathrust earthquake ruptures in Central Chile using logic tree analysis

3D fault model and seismotectonics indicate the potential seismic risk in the Daliang Mountains, southeastern Tibetan Plateau

Areas of active tectonics host many active faults and frequently experience moderate to large earthquakes. The possibility of devastating earthquakes makes the development of major infrastructure projects in these areas risky. World-class large-scale step hydroelectric projects have been built along the Jinsha River, such as the Xiangjiaba, Xiluodu, Baihetan and Wudongde reservoirs in the Daliang Mountains of the southeastern Tibetan Plateau. Using the SKUA-GoCAD modelling platform, we created a thorough 3D model of the active faults. Regional geological information, historical strong earthquake catalogues, small earthquakes with fine displacement and 3D seismic tomography are all integrated in this model. The Mabian–Yanjin fault belt consists of a number of discontinuous faults that are either exposed on the surface or concealed, according to the 3D fault model. Some destructive earthquakes, including two enormous M s 7 and many moderate earthquakes, have occurred along this fault belt. Some pre-existing thrust faults, together with numerous immature faults in specific areas, may have been reactivated and changed into strike-slip faults. The Jinsha River basin's seismic and geological concerns must be carefully considered given the existence of such intricate fault networks and seismic activity. Supplementary material: A video of the 3D fault model is available at https://doi.org/10.6084/m9.figshare.c.6949201

Intrinsic and scattering attenuations of the Sichuan-Yunnan region in China from S coda waves

Seismic attenuation is a fundamental property of the Earth's media. Attenuation structure for the complicated geological structures with strong seismicity in the Sichuan-Yunnan region is poorly studied. In this study, we collected 108,399 waveforms of 11,517 local small earthquakes with magnitudes between 1.5 and 3.5 from January 2014 to September 2021 in the Sichuan-Yunnan region and its adjacent areas. We employed an envelope inversion technique for separating the intrinsic and scattering attenuations of the S coda wave, and obtained the intrinsic and scattering attenuation structures for frequencies between 0.25 and 8.00 Hz. The attenuation structures correlate well with the geological units, and some major faults mark the attenuation variations where historic large earthquakes have occurred. The regional average attenuation shows a negative frequency dependence. The average scattering attenuation has a faster descending rate than the average intrinsic attenuation, and is dominant at low frequencies, while at high frequencies the average intrinsic attenuation is stronger. The lateral variation in the intrinsic attenuation is consistent with the variation in heat flow, the scattering attenuation may be related to the scatter distribution and size. The total attenuation is consistent with the previous studies in this region, and the separate intrinsic and scattering attenuation may be useful in understanding regional tectonics and important in earthquake prevention and disaster reduction.

Active Tectonics, Quaternary Stress Regime Evolution and Seismotectonic Faults in Southern Central Hispaniola: Implications for the Quantitative Seismic Hazard Assessment

AbstractPresent‐day convergence between Caribbean and North American plates is accommodated by subduction zones, major active thrusts and strike‐slip faults, which are probably the source of the historical large earthquakes on Hispaniola. However, little is known of their geometric and kinematic characteristics, slip rates and seismic activity over time. This information is important to understand the active tectonics in Hispaniola, but it is also crucial to estimate the seismic hazard in the region. Here we show that a relatively constant NE‐directed shortening controlled the geometry and kinematics of main active faults in southern central Hispaniola, as well as the evolution of the Quaternary stress regime. This evolution included a pre‐Early Pleistocene D1 event of NE‐trending compression, which gave rise to the large‐scale fold and thrust structure in the Cordillera Central, Peralta Belt, Sierra Martín García and San Juan‐Azua basin. This was followed by a near pure strike‐slip D2 stress regime, partitioned into the N‐S to NE‐SW transverse Ocoa‐Bonao‐La Guácara and Beata Ridge fault zones, as well as subordinate structures in related sub‐parallel deformation corridors. Shift to D2 strike‐slip deformation was related to indentation of the Beata Ridge in southern Hispaniola from the Early to Middle Pleistocene and continues today. D2 was locally coeval by a more heterogeneous and geographically localized D3 extensional deformation. Defined seismotectonic fault zones divide the region into a set of simplified seismogenic zones as starting point for a seismic hazard modeling. Highest peak ground acceleration values computed in the Ocoa Bay establish a very high seismic hazard.

Remote Sensing based Early Warning Systems for Detection and Assessment of Landslides: A Case Study of Himachal Pradesh, India

Case studies within the framework of "Remote Sensing-Based Early Warning Systems for Slope Failures" present real-world instances of applying remote sensing technologies in monitoring slopes and detecting changes in elevation. The study focuses on Himachal Pradesh, India, known for its rugged terrain and varying climatic conditions. Himachal Pradesh, situated in North-West India, spans from 30°22'40" to 33°12'20" north latitudes and 75°45'55" to 79°04'20" east longitudes. With altitudes ranging from 271 meters to 6,751 meters, this mountain region exhibits diverse topography and climate. Geospatial data reveals its complexities, combining elevation, slope, hillside and roughness information to offer insights into the terrain's dynamics. The geological map highlights the State's Precambrian formations shaped by the collision of the Indian and Asian landmasses, resulting in the distinctive Himalayan landscape. The region has also experienced concentrated orographic precipitation, glacial activity and rapid erosion. Analyzing historical earthquakes and active faults reveals the seismic activity's correlation with landslides, highlighting their potential to trigger slope failures. The landslide inventory map records 6,289 landslides, outlining their distribution and movement patterns. Further insight is gained from the Landslide sustainability map, classifying regions into susceptibility levels. Integrated geospatial analyses provide a comprehensive understanding of Himachal Pradesh's terrain, offering practical applications in risk assessment, infrastructure planning and environmental conservation.

Sedimentary Records in the Lesser Antilles Fore‐Arc Basins Provide Evidence of Large Late Quaternary Megathrust Earthquakes

AbstractThe seismic potential of the Lesser Antilles subduction zone is poorly known and highly debated. Only two damaging earthquakes have been reported in the historical period, in 1839 and 1843, but their sources and magnitude are still uncertain. Global Navigation Satellite Systems and coral data contradict each other, and no conclusion has been reached on the coupling ratio of the plate interface. Given the threat posed by the possible occurrence of a large megathrust earthquake, it is crucial to gain information on prehistorical events. We present the results of a submarine paleoseismological study that covers an exceptional ∼120 Kyr‐long period. We studied the sediments sampled in six up to 26 m‐long piston cores collected in deep fore‐arc basins located over the epicentral region of the 1843 earthquake. Using a multiproxy approach combining geophysical, geochemical, and sedimentological analysis, biostratigraphy and radiocarbon dating, we identified, characterized, and dated numerous event deposits that we then correlated with the sampled basins over an up to 160 km‐long area. We show that at least 33 earthquakes likely triggered these sediment remobilizations in the last 120 Kyr. Four of these events promoted exceptional deposits of turbidites + homogenites. From peak ground acceleration calculated for potential earthquakes occurring on various faults, and the absence of deposits linked to the historical earthquakes, we propose that the sources are likely megathrust earthquakes. Over the last 60 Kyr, we inferred at least three 15–25 Kyr‐long seismic cycles in which the recurrence times of earthquakes shortens from ∼5 to ∼2 Kyr.

Networks of geometrically coherent faults accommodate Alpine tectonic inversion offshore southwestern Iberia

Abstract. The structural styles and magnitudes of Alpine tectonic inversion are reviewed for the Atlantic margin of southwestern (SW) Iberia, a region known for its historical earthquakes, tsunamis and associated geohazards. Reprocessed, high-quality 2D seismic data provide new images of tectonic faults, which were mapped to a depth exceeding 10 km for the first time. A total of 26 of these faults comprise syn-rift structures accommodating vertical uplift and horizontal advection (shortening) during Alpine tectonics. At the regional scale, tectonic reactivation has been marked by (a) the exhumation of parts of the present-day continental shelf, (b) local folding and thrusting of strata at the foot of the continental slope, and (c) oversteepening of syn- and post-rift sequences near reactivated faults (e.g. “passive uplift”). This work proves, for the first time, that geometric coherence dominated the growth and linkage of the 26 offshore faults mapped in SW Iberia; therefore, they are prone to reactivate as a kinematically coherent fault network. They form 100–250 km long structures, the longest of which may generate earthquakes with a momentum magnitude (Mw) of 8.0. Tectonic inversion started in the Late Cretaceous, and its magnitude is greater close to where magmatic intrusions are identified. In contrast to previous models, this work postulates that regions in which Late Mesozoic magmatism was more intense comprise thickened, harder crust and form lateral buttresses to northwest–southeast compression. It shows these structural buttresses to have promoted the development of early stage fold-and-thrust belts – typical of convergent margins – in two distinct sectors.

Local site effects and seismic microzonation around Suban Area, Curup Rejang Lebong, Bengkulu deduced by ambient noise measurements

BackgroundThe Suban area of Curup Rejang Lebong is a tourist region in Bengkulu Province, Indonesia, close to the active Ketaun and Musi faults, which are segments of the Sumatra Fault System (SFS). However, no studies have been conducted in this area to assess how geological structures affect seismic ground motions and contribute to seismic hazard and risk assessment.MethodsThe first study of seismic microzonation in the Suban area of Curup City by ambient noise measurements was conducted at 100 sites, spaced ~ 1 km apart, with 60 min of data acquisition for each site. All microseismic data were processed using the Horizontal to Vertical Spectral Ratios (HVSR) method.ResultsThe HVSR method revealed the amplification factors (A0) ranging from 1.23 to 8.26 times, corresponding to natural frequency (f0) variations between 1.24 and 9.67 Hz. About 13% and 55% of the sites show high (6 ≤ A0 ≤ 9) and medium (3 ≤ A0 ≤ 6) amplifications, respectively, predominantly in the western parts of the study area, consistent with a high seismic vulnerability index (Kg). Furthermore, we also estimated the ground shear strain (GSS) of the region using the Kanai method with two large historical earthquakes at the Ketahun segment in 1943 (Mw 7.4) and the Musi segment in 1979 (Mw 6.0). The Kg value is consistent with the GSS values and indicates areas of severe damage during the historic earthquakes.ConclusionsThus, the western parts of the Suban region are vulnerable to severe damage from an earthquake. These findings could provide valuable insights for future planning and risk management efforts aimed at minimizing the impact of earthquakes in the Suban region.

Palaeoseismological assessment for a seismic gap located very close to the epicentre of the 30 October 2020 Samos Earthquake (M6.9), western Anatolia, Turkey

AbstractThe Tuzla Fault (TF), considered one of the most important seismic sources in İzmir province, is defined as a strike–slip fault with N10E–N60E striking between Gaziemir and Doğanbey districts. A 50-km-long fault consists of three segments which are, from north to south Çatalca, Orhanlı, and Doğanbey segments. Recent studies claim that the part of the TF extending to Kuşadası Bay is also in a kinematic relationship with the Samos Fault that caused an earthquake on 30 October 2020 (Mw = 6.9). In this study, in order to analyse the historical behaviour of the fault, three trench-based palaeoseismology studies across the fault scarp were conducted on three geometric segments of the TF. Palaeoseismology findings show that seven historic/prehistoric earthquakes were generated by TF. According to Oxcal distribution using the Bayesian methods, the time of the events lie between 46.2 ± 6.1 and 1.6 ± 0.3 ka. When the events are compared with the historical earthquakes, the last event is correlated with the earthquakes of 47 AD and/or 177/178 AD on the Doğanbey segment. Moreover, the other events can be attributed to the late Pleistocene–Holocene earthquakes that are prehistorical periods. Our results provide a recurrence interval of an earthquake along the TF to between 0.7 and 4.3 ka for the Holocene period. The elapsed time since the most recent surface faulting earthquake on the TF is 1844 years. It is suggested that it is predicted that TF has the potential to produce destructive earthquakes in the near future, especially in Orhanlı and Çatalca segments which may be considered as a seismic gap.

Mean period prediction models for Mexican interplate and intermediate-depth intraslab earthquake ground motions

The aim of this paper is to predict the mean period, Tm, as a measure of the frequency content of interplate and intermediate-depth intraslab earthquake ground motions recorded at rock sites due to subduction earthquakes in Mexico. For this purpose, both Ground Motion Prediction Models (GMPMs), which use a parametric regression, and Support Vector Machine (SVM) regression, a type of machine learning algorithm used for regression analysis, are employed in this investigation. Therefore, two databases which include 484 and 300 earthquake ground motions recorded during interplate and intraslab historical Mexican earthquakes were assembled in this study. It is shown that Tm estimates depend on the type of earthquake (i.e., interplate or intraslab). While the SVM regression yields the lowest total standard deviation in predicting Tm, the GMPM still yields an acceptable total standard deviation similar to that reported in other studies. A comparison of the GMPM for intraslab earthquakes in Mexico with another GMPMs for predicting Tm recently introduced in the literature showed differences, which suggests that GMPMs for predicting Tm should be developed for specific regions.

Effectiveness of installing multiple tuned mass dampers for seismic mitigation of steel–concrete wind turbine hybrid tower

The concept of a steel–concrete hybrid tower (SCHT) has recently been proposed to satisfy the demand for wind turbine hub higher than 120 m. This study details the effect of tuned mass dampers (TMDs) on the seismic mitigation of SCHTs. The equation of motion of the coupled system was formulated using a multi-degree-of-freedom system equivalent to the SCHT. The optimum properties of the TMDs were identified to control the tower multimode responses using the frequency-domain approach. Finally, time-history analyses were conducted to evaluate the effectiveness of the optimised TMDs on the SCHT under an ensemble of 22 historical earthquakes. The reasons why the TMDs cannot always achieve the expected control performance for the SCHT are explained.

A kinematic method for generating earthquake sequences

Computational earthquake sequence models provide generative estimates of the time, location, and size of synthetic seismic events that can be compared with observed earthquake histories and assessed as rupture forecasts. Here we describe a three-dimensional probabilistic earthquake sequence model that produces slip event time series constrained across geometrically complex non-planar fault systems. This model is kinematic in nature, integrating the time evolution of geometric moment accumulation and release with empirical earthquake scaling laws. The temporal probability of event occurrence is determined from the time history of geometric moment integrated with short-term Omori-style rate decay following each earthquake achieving long-term time-averaged moment balance. Similarly, the net geometric moment monotonically controls the probability of event localization, and seismic events release geometric moment with spatially heterogeneous slip on three-dimensional non-planar fault surfaces. We use this model to generate a synthetic earthquake sequence on the Nankai subduction zone over a 1,250-year-long interval, including 700+ MW=5.5−8.5 coseismic events, with decadal-to-centennial scale quiescent intervals quasi-periodic great earthquake clusters followed by aftershock sequences.

An investigation on the effects of using TMD for vibration control on the response of high-rise buildings to seismic excitation

This paper demonstrates that a tuned mass damper (TMD) is capable of effectively reducing vibration in high-rise buildings during seismic events. This study examines the effects of vibration control on the displacements and accelerations of controlled and uncontrolled buildings. It analyses their modal responses using an algorithm in MATLAB software. This study utilised instances of vibration control in models of a six-story and twelve-story skyscraper. The dynamic response of six-story buildings was assessed using two historical earthquakes, namely El Centro (1940) and Boumerdes (2003). The twelve-story skyscraper experienced two further significant earthquakes, namely Northridge (1994) and Kobe (1995). The building has undergone digital simulation, specifically modelling the displacement of the top story. Consequently, the structure equipped with the Tuned Mass Damper (TMD) system exhibits reduced displacement and acceleration compared to the structure without TMD. The implemented TMD system resulted in a displacement reduction of less than 45% in high-rise buildings subjected to seismic excitation.