The evaluation of seismic site amplification and its relationship with geological structures play a vital role in earthquake engineering and hazard assessment. This study presents an analysis of ...topographic and geologic site amplification effects observed in the Qiaozhuang region, Sichuan Province, China. Seismic recordings at several monitoring stations installed on two slopes located at a distance of about 1 km in the study area after the 2008 Wenchuan earthquake provide evidence of strong and variable amplifications. To assess the combined effect of topographic and geological controls in slope response to seismic motions, we built 2D and 3D dynamic numerical models using monitoring data as inputs. Four layers with different P-wave velocities, based on geophysical survey in the study area, are considered in the numerical models. Models that only consider topography give an amplification factor of <3, which is much lower than the amplification factor of 5–6 from the monitoring data, while those models that considered both the topographic variation and four layers agree well with the monitoring data. The 3D modeling results show that the subsurface amplification factor is less than that on the slope surface even at the same elevation. This is also consistent with the monitoring data and further indicates that the combined topographic and geological amplification effect on the slope surface is more significant than the sole geological amplification effect inside the slope. Our numerical simulation results suggest that it is important to consider the combined topographic and geological amplification effects in the hazard assessment of seismically induced slope failures.
•This study presents long-term monitoring data of slope seismic response.•Homogeneous numerical models show that topography alone only produces low amplification effects.•The results from three-layer heterogenous 3D model indicat the importance of geological amplification effect.
The seismic events on February 6, 2023, in the province of Kahramanmaraş/Türkiye, caused severe damage and the collapse of numerous structures due to underlying soil issues. This catastrophe revealed ...the inevitable requirement to evaluate the effect of soil profile on structural safety. In the present study, novel artificial intelligence (AI) functions based on the three-dimensional finite element (3D FE) method considering various soil parameters were developed to predict the effects of earthquakes. A 3D FE model of the ten-story building with a known soil profile and structural elements was created in the first stage, accounting for the soil-pile-structure interaction. After model validation, numerous parametric time history earthquake analyses were performed using the February 6 Pazarcık/Kahramanmaraş (Mw = 7.7) earthquake records. Therefore, the effects of soil parameters on acceleration, settlement, and lateral deformations were investigated. An innovative coding infrastructure, leveraging the power of AI, was developed to generate optimal network solutions automatically for creating high-order regression prediction functions. The 3D FE data was integrated into the code, and subsequently, an artificial neural network was utilized to formulate a function that yielded statistically significant outcomes. The created function accurately predicted the accelerations, settlements, and deformations. A novel method for indicating the potential deformations and accelerations inflicted by earthquakes based on soil parameters was introduced. This methodology can serve as a practical guide for researchers and project implementers in the initial design phases.
•Earthquake effects for various soil parameters were investigated.•Numerous parametric 3D finite element analyses were conducted to provide data for AI.•Novel AI functions were developed to guide researchers in earthquakes.
The information and seismic parameters gained from pre-instrumental earthquakes are essential to improve the seismic catalogs and hazard studies. The earthquake damage (ED) that affected ...architectonic elements during earthquakes (e.g. fallen walls, conjugated fractures in walls, dropped keystones in arches), and when this earthquake damage is orientated (EDO), can be used to infer seismic parameters of pre-instrumental earthquakes such as epicenter location, seismogenic source or ground motion. However, there is not a common methodology to measure this orientation damage. For example, tilting and fallen walls are some of the most used elements to infer the horizontal ground motion in non-instrumental earthquakes. Nevertheless, according to the shape of the architectonic element (a wall in this case), it has only two degrees of freedom to fall, and therefore, its azimuth does not necessarily fit with the ground motion pulse orientation. In this work, a review of the earthquake damage (ED) and effects described in pre-instrumental earthquakes is carried out. A method is also proposed, considering not only the frequency of damage orientations but also considering the uncertainty angle of each element to be damage. The ED has been classified into five groups according to the angle of uncertainty to record the pulse orientation. This method has been checked taking advantage of recent earthquakes with a good instrumental record of the ground motion pulse, and also tested modeling different scenarios with different pulse orientations. This method, that takes into account the uncertainty angles, is a reliable method to calculate the EDO and back-calculate the ground motion pulse orientation in pre-instrumental earthquakes in absence of more accurate modern instrumental records. This method can also be useful for seismic risk assessment and restoration and protection of historical heritage.
On 12th of November 2017, a major earthquake of a magnitude of M 7.3 hit Halabja and caused severe structural damage and collapse in Iran, however, only a few areas of Iraq were mildly affected by ...it. It was considered the deadliest earthquake of the year as its casualties surpassed 400 people most of which were in Iran. Halabja, was only 32 km away from the epicenter, yet the quake caused no noticeable structural damage to the buildings and no casualties or serious injuries were reported from there. This paper presents the possible engineering reasons behind the gigantic gap of severity of the damage between Kurdistan region of Iraq and Iran. The analysis is done after a series of site visit to Darbandikhan and Halabja and taking more than 300 photographs of the damaged and collapsed buildings. Several crucial factors are discussed in detail, the major of which is directionality effects of the quake as its epicenter was in Iran and the quake caused a meter of slip towards south and half a meter of displacement towards west of the epicenter. Due to the directionality effect, the damage was more in the south and the west of the epicenter knowing that most parts of Kurdistan region of Iraq were located at the north of the epicenter. It is also found that the geological location of the buildings was insignificant in increasing the damage level of the buildings.
Chile has unevenly distributed water resources, limited water level stations and earthquake-prone geological conditions, making it difficult to accurately and comprehensively monitor Chile's ...terrestrial water storage (TWS) variations. The Gravity Recovery and Climate Experiment (GRACE) has been widely used to estimate TWS variations. This study uses GRACE solutions and a method of eliminating earthquake effects to estimate TWS variations. The estimation results with earthquake effects deducted show that the rate of TWS variation in Chile is generally a decreasing trend of −0.16 ± 0.096 cm year
−1
. Furthermore, in the target period, precipitation mainly decreased and evapotranspiration increased. Correlation coefficients between TWS variations, precipitation and evapotranspiration are less than 0.4, suggesting that the factors in TWS are more complex. Temperature also shows an increasing trend of 0.06°C year
−1
in Chile. This information will help to understand the characteristics of the TWS variation in Chile and its response to climate change.
This open access book presents a methodology for the assessment of structural building details, taking into account the contemporary guidelines for earthquake-resistant and energy-efficient ...buildings. A review of structural details for energy-efficient buildings revealed that in some cases the structural system is interrupted, leading to solutions which are not suitable for earthquake-prone regions. Such typical examples would be the use of thermal insulation under the building foundation and reduction of the load-bearing elements’ dimensions – also at the potential locations of plastic hinges which are crucial for the dissipation of seismic energy. The proposed methodology of assessment favours a collaboration of architects, engineers, contractors and investors in the early stage of building design. By this the methodology enables efficient decision-making and contributes to a selection of optimal building structural details. The book starts by presenting the typical structural details of the thermal envelope of energy-efficient buildings together with the scientific background required for understanding the process of detail development from all the relevant aspects. Over 20 examples of most frequent details are described and analysed to raise awareness of the importance of earthquake resistance, sustainability, energy-efficiency and thermal comfort for users.
Subsidence after a subduction zone earthquake can cause major changes in estuarine bathymetry. Here, we quantify the impacts of earthquake‐induced subsidence on hydrodynamics and habitat ...distributions in a major system, the lower Columbia River Estuary, using a hydrodynamic and habitat model. Model results indicate that coseismic subsidence increases tidal range, with the smallest changes at the coast and a maximum increase of ∼10% in a region of topographic convergence. All modeled scenarios reduce intertidal habitat by 24%–25% and shifts ∼93% of estuarine wetlands to lower‐elevation habitat bands. Incorporating dynamic effects of tidal change from subsidence yields higher estimates of remaining habitat by multiples of 0–3.7, dependent on the habitat type. The persistent tidal change and chronic habitat disturbance after an earthquake poses strong challenges for estuarine management and wetland restoration planning, particularly when coupled with future sea‐level rise effects.
Plain Language Summary
The land in many estuaries along the Pacific Rim has been repeatedly changed by major earthquakes. Previous earthquakes, such as the CE 1700 rupture along the 1,000‐km Cascadia Subduction Zone of western North America, produced as much as 2 m of land‐surface lowering. This study employs a hydrodynamic model to show that the relative sea‐level rise resulting from such lowering would increase tidal range and affect nearly all existing wetland habitat in the lower Columbia River Estuary. In our primary scenario, approximately ∼93% of current wetland habitat converts to lower‐elevation types, with changes largely due to land‐surface lowering but also influenced by tidal changes. Thus, the chronic, long‐term disturbance to habitat conditions after an earthquake poses a similar long‐term risk to estuarine ecology as extreme global sea‐level rise scenarios. Understanding such earthquake effects may assist the development of more resilient habitat restoration strategies.
Key Points
Earthquake‐induced subsidence results in the movement of ∼93% of intertidal habitat to lower habitat zones
Post earthquake, tidal range increases by up to 0.25 m in channels; capturing such changes requires a dynamic model
Both subsidence and changes in tidal range alter habitats, especially sandflats and low marshes
•Steel fibers display better seismic performance over steel rebar in tunnel linings.•fr4-PGA-Probability of Seismic Damage relationships is proposed for SFRC tunnels.•A hybrid SFRC mix, with higher ...content of micro fibers, shows best seismic behavior.
In recent years, application of fibers as a replacement for conventional reinforcement in segmented lined tunnels has gained great interest due to resulting cost and time savings. In seismically active regions, the seismic vulnerability of underground tunnels is of great concern. The aim of this paper is to investigate the effects of different composites of Steel FRC (SFRC), as the tunnel’s lining material, on its seismic vulnerability, compared to each other and to that of unreinforced and conventionally reinforced concrete cases, employing analytical fragility curves. Results show that steel fibers, especially micro size fibers and for higher states of damage, display better seismic performance over conventional steel rebar in reinforced concrete linings. For best performance, a hybrid SFRC mix containing both micro and macro fibers, with a higher content of micro fibers over macro ones, is a technically preferable option for the design of segmental lining tunnels in seismic zones.
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