The Stochastic Finite-Fault Modeling Based on a Dynamic Corner Frequency Simulating of Strong Ground Motion for Earthquake Scenario of North Tabriz Fault

The occurrence of the historical and machine Earthquakes, near to the North Tabriz Fault in NW Iran is an evidence for the seismic activity of this fault, which records a historical earthquake with a magnitude more than 7. Using the existing experimental relations, seismicity, and the fault geometry, a Mw 7.7 earthquake scenario was defined. The stochastic finite-fault modeling based on a dynamic corner frequency shows good agreement with common attenuation patterns. The shake map illustrates that Baghmisheh, Roshtieh, Ellahieh, Valiamr, and Eram region on Tabriz are at high hazard areas, and the maximum acceleration is located at the north direction with the same azimuth similar to fault strike.

Simulation of strong earthquake characteristics of a scenario earthquake(M_(S)7.5)based on the enlightenment of 2022 M_(S)6.9 earthquake in Menyuan

The Menyuan area is an important transportation hub in the Hexi Corridor.The Menyuan M_(S)6.9 earthquake that occurred on January 8,2022 had a major impact on the local infrastructure and transportation of this region.Due to the high possibility of similar strong earthquakes occurring in this area in the future,preliminary assessment of the seismic intensity characteristics of destructive earthquakes in this region is essential for effective disaster control.This paper uses the empirical Green′s function(EGF)method as a numerical simulation tool to predict the ground motion intensity of Datong Autonomous County under the action of the scenario earthquake(M_(S)7.5).Seismic records of aftershocks of the 2016 Menyuan M_(S)6.4 earthquake were used as Green’s functions for this simulation.The uncertainties associated with various source parameters were considered,and 36possible earthquake scenarios were simulated to obtain 72 sets of horizontal ground motions in Datong County.The obtained peak ground acceleration(PGA)vs.time histories of the horizontal ground motion were screened using the attenuation relationships provided by the fifth-edition of China’s Seismic Ground Motion Parameter Zoning Map and the NGA-West2dataset.Ultimately,32 possible acceleration-time histories were selected for further analysis.The screened PGA values ranged from 78.8 to 153 cm/s^(2).The uncertainty associated with the initial rupture point was found to greatly affect the results of the earthquake simulation.The average acceleration spectrum of the selected acceleration-time history exceeded the expected spectrum of a intermediate earthquake,which means that buildings in Datong County might sustain some damage should the scenario earthquake occur.This research can provide reliable ground motion input for urban earthquake damage simulation and seismic design in Datong County.Growing the dataset of small earthquakes recorded in this region will facilitate the large-scale simulation of ground motions under different earthquake scenarios.

Prediction of near-field strong ground motions for scenario earthquakes on active fault

A method to predict near-field strong ground motions for scenario earthquakes on active faults is proposed. First, macro-source parameters characterizing the entire source area, i.e., global source parameters, including fault length, fault width, rupture area, average slip on the fault plane, etc., are estimated by seismogeology survey, seismicity and seismic scaling laws. Second, slip distributions characterizing heterogeneity or roughness on the fault plane, i.e., local source parameters, are reproduced/evaluated by the hybrid slip model. Finally, the finite fault source model, developed from both the global and local source parameters, is combined with the stochastically synthetic technique of ground motion using the dynamic comer frequency based on seismology. The proposed method is applied to simulate the acceleration time histories on three base-rock stations during the 1994 Northridge earthquake. Comparisons between the predicted and recorded acceleration time histories show that the method is feasible and practicable.

Comparison of Design Response Spectrum for Long Period Structures Based on Scenario Earthquakes

Two kinds of determining methods for scenario earthquakes are presented in this paper,namely the weighted average method and maximum probability method. This paper briefly introduces the two methods,then taking a high-rise building in the Yantai area as a case study,we use the weighted average method and maximum probability method to realize seismic hazard analysis, determine earthquake magnitude, the epicenter and specific space position,and then give two response spectrums of the two methods. By comparing the differences of response spectrums between the two methods,we find that the weighted average method is more suitable for long period structures,while considering long period safety. The maximum probability method is more suitable for short period structures. It is reasonable to choose a corresponding different method when the structures have different natural vibration periods.

Simulation of Ground Motion at Guanting Reservoir Dam Based on the Scenario Earthquake in the Yanqing-Huailai Basin

Research at home and abroad shows that the simulation of ground motion using the 3D finite-difference method might be accurate and feasible. Based on related theories and methods,and using the wave velocity and density model of the crust in the Yanqing-Huailai Basin,this paper makes a simulation of ground motion at Guanting Reservoir Dam based on the scenario earthquake in the Yanqing-Huailai Basin. Comparative analysis shows that the results of 3D finite-difference simulation accord with those of the empirical formula. The parameters such as the velocity-time series of ground motion,PGV and frequency might be referred to for the analysis of seismic protection design of the dam's structure.

Envelope Functions of Time Histories in Seismic Safety Evaluation and Scenario Earthquakes

It has been a period of time since the concept of scenario earthquake was proposed, but this concept has rarely been used in seismic safety evaluation in China since then. Meanwhile, because of the uncertainties of magnitudes-distances pairs, there is large arbitrariness while determining the envelope function of time histories in seismic hazard analysis. In this paper, we describe a method to control the envelope functions of the time histories by introducing the most-likely combinations of magnitude and distance of the scenario earthquakes based on a probabilistic method, revise the software of the ellipse model for seismic hazard analysis, and give a computation example.

Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern China.It is important to improve the understanding of seismic hazard assessments in areas near faults.We start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu Fault.The fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake magnitude.Considering the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation model.Our findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake case.We compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial stress.For the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip rate.The response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

Probability-consistent earthquakes and probability-consistent conservative earthquakes

It is pointed out in this paper that the concept of scenario earthquake, expectant earthquake or proposed earthquake suggested by Kameda Nojima (1988) is not probability consistent due to unfit understanding for the aseismic design standard of probabilistic method. The corresponding concept proposed by QI FENG LUO meets the meaning of probability consistent, but it is still in a meaning of average so the result is not good enough. On the basis of above analysis, a concept of probability consistent conservative earthquakes is suggested. And a new method selecting aseismic objective earthquake with physical meaning is proposed on the basis of probabilistic method. After seismic hazard is analysed by certain control parameters, such as peak acceleration, we can determine the aseismic standard according to certain probabilistic level. Based on the attenuation law and the potential sources, we can find out some earthquakes or their combinations of magnitudes and distances. Such earthquakes or combinations are probability consistent for this control parameter. Based on above parameter, we suggest considering the destructive effects of other parameters (such as response spectrum), and selecting conservative earthquakes to replace the average earthquake and meet the requirements of aseismic design better.

Research on Earthquakes in Cities of China

In this paper, we briefly describe the general destruction caused by historic earthquakes in major cities of China, preliminarily analyze the heaviness and widespread occurrence of earthquakes in cities of China, and suggest that research on scenario earthquakes in cities should be developed as a part urban disaster reduction research.

The housing loss assessment of rural villages caused by earthquake disaster in Yunnan Province

Based on the assessment report of destructive housings caused by more than 20 earthquakes occurred in Yunnan Province in 1990~2004, the vulnerability models of 4 types housings of rural residents in Yunnan Province are setup. The scenario earthquake disaster loss model is used to simulate the housing loss if the historical earthquakes that occurred since A.D. 886 in Yunnan Province reoccur in 2002. The analyses show the simulation deviation of the usual earthquakes is less than 30% and the method is of high practicality. Meanwhile, the simulation result of 398 historical earthquakes in Yunnan Province shows that the annual economic loss caused by the earthquakes is about RMB 410 million Yuan that accounts for 0.18% of GDP of Yunnan Province for the year. Because the per capita living area and the price of the housing increases year by year, if the historical destructive earthquake reoc- curs today, the loss of Yunnan Province will be greater than in those years.

Seismic vulnerability assessment of urban buildings using the rough set theory and weighted linear combination

Seismic vulnerability assessment of urban buildings is among the most crucial procedures to post-disaster response and recovery of infrastructure systems.The present study proceeds to estimate the seismic vulnerability of urban buildings and proposes a new framework training on the two objectives.First,a comprehensive interpretation of the effective parameters of this phenomenon including physical and human factors is done.Second,the Rough Set theory is used to reduce the integration uncertainties,as there are numerous quantitative and qualitative data.Both objectives were conducted on seven distinct earthquake scenarios with different intensities based on distance from the fault line and the epicenter.The proposed method was implemented by measuring seismic vulnerability for the seven specified seismic scenarios.The final results indicated that among the entire studied buildings,71.5%were highly vulnerable as concerning the highest earthquake scenario(intensity=7 MM and acceleration calculated based on the epicenter),while in the lowest earthquake scenario(intensity=5 MM),the percentage of vulnerable buildings decreased to approximately 57%.Also,the findings proved that the distance from the fault line rather than the earthquake center(epicenter)has a significant effect on the seismic vulnerability of urban buildings.The model was evaluated by comparing the results with the weighted linear combination(WLC)method.The accuracy of the proposed model was substantiated according to evaluation reports.Vulnerability assessment based on the distance from the epicenter and its comparison with the distance from the fault shows significant reliable results.

Stochastic simulation of ground motions based on NGA-West2 strong motion records

Stochastic modeling of ground motion is a simple tool to predict ground shaking level for future earthquake and less time consuming than physics-based deterministic modeling.In this paper,a record-based stochastic method that considers the time-and frequency-evolution of ground motion is used to estimate ground motion for scenario earthquakes in tectonic active region.The stochastic method employs a time-domain modulation function to describe the temporal nonstationarity and a filter impulse response function that describe the evolution of frequency content.For characterizing the modulation function and the filter impulse function,six parameters(Ia,D5-95,tmid,ωmid,ω',ξf)are defined,and 2,571 pairs of ground motion recording in the NGA-west2 database are selected to identify the six parameters.Probabilistic density function is assigned to each of the parameter by fitting the frequency distribution histogram.The parameters are then transformed into standard normal space where regression analysis is performed by considering each parameter as function of moment magnitude,rupture distance,vS30(The time-averaged shear wave velocity of the top 30 m of soil).The prediction equations are used to generate ground motions for several scenario earthquakes and compared to NGA-West2 GMPEs.

A Physics‑Based Seismic Risk Assessment of the Qujiang Fault:From Dynamic Rupture to Disaster Estimation

This study achieved the construction of earthquake disaster scenarios based on physics-based methods-from fault dynamic rupture to seismic wave propagation-and then population and economic loss estimations.The physics-based dynamic rupture and strong ground motion simulations can fully consider the three-dimensional complexity of physical parameters such as fault geometry,stress field,rock properties,and terrain.Quantitative analysis of multiple seismic disaster scenarios along the Qujiang Fault in western Yunnan Province in southwestern China based on different nucleation locations was achieved.The results indicate that the northwestern segment of the Qujiang Fault is expected to experience significantly higher levels of damage compared to the southeastern segment.Additionally,there are significant variations in human losses,even though the economic losses are similar across different scenarios.Dali Bai Autonomous Prefecture,Chuxiong Yi Autonomous Prefecture,Yuxi City,Honghe Hani and Yi Autonomous Prefecture,and Wenshan Zhuang and Miao Autonomous Prefecture were identified as at medium to high seismic risks,with Yuxi and Honghe being particularly vulnerable.Implementing targeted earthquake prevention measures in Yuxi and Honghe will significantly mitigate the potential risks posed by the Qujiang Fault.Notably,although the fault is within Yuxi,Honghe is likely to suffer the most severe damage.These findings emphasize the importance of considering rupture directivity and its influence on ground motion distribution when assessing seismic risk.