Stochastic Finite-Fault Simulation of the Ms 7.0 Lushan Earthquake Based on Frequency- and Distance-Dependent Radiation Patterns

2021 ◽  
Author(s):  
Tianjia Wang ◽  
Xu Xie ◽  
Longfei Ji
Keyword(s):  
Radiation Pattern ◽  
Ground Motion ◽  
Low Frequency ◽  
Time History ◽  
Lushan Earthquake ◽  
Radiation Patterns ◽  
Improved Method ◽  
High Frequencies ◽  
Finite Fault ◽  
Finite Fault Method

ABSTRACT The stochastic finite-fault method (EXSIM) has been extensively used for simulating ground motion at high frequencies. However, its poor performance in low-frequency simulations is a limiting factor that restricts its engineering application. Refining the representation of the radiation pattern in the finite-fault method is an effective strategy to improve low-frequency simulations; to this end, a frequency-dependent radiation pattern has been considered by several researchers. However, this strategy fails to provide an accurate simulation of seismic-wave propagation at distances beyond the near-fault region. Researchers have proposed various approaches for characterizing the radiation pattern variation with distance. This study introduces frequency- and distance-dependent radiation patterns of S waves to the EXSIM. The near-field acceleration records in the east–west and north–south directions of the 2013 Ms 7.0 Lushan earthquake were reconstructed. The proposed method was verified by: (1) comparing broadband simulation results obtained by the improved method with observed results, (2) conducting a misfit analysis to compare the model bias between the improved and original methods, and (3) comparing the observed and simulated peak ground acceleration data with the predicted values of the ground-motion prediction equations (GMPEs) to verify the effectiveness of the GMPEs in describing the regional ground-motion attenuation. The results indicated that the 5%-damped pseudo spectral accelerations at high frequencies (1–20 Hz) and acceleration time history simulated by the improved method were consistent with the observed values. Furthermore, the improved method effectively optimizes the simulation effect at low frequencies (0.05–1 Hz) compared with the original method. Thus, the improvement in the representation of the radiation pattern in EXSIM can better estimate broadband ground motion in the study area.

An Improved Stochastic Finite-Fault Method Based on Energy

2015 ◽  
Vol 744-746 ◽  
pp. 878-883
Author(s):  
Ju Fang Zhong ◽  
Jun Wei Liang ◽  
Zhi Peng Fan ◽  
Luo Long Zhan
Keyword(s):  
Ground Motion ◽  
Amplification Factor ◽  
Response Spectrum ◽  
Near Field ◽  
Energy Accumulation ◽  
Accumulation Curve ◽  
Finite Fault ◽  
Acceleration Time Histories ◽  
Time Histories ◽  
Finite Fault Method

Owing to the simulated ground motion energy distribution by stochastic finite-fault method is not reasonable, near-field bedrock strong ground motion acceleration time histories are used to study. Fourier transform is adapted to analysis the variation of the energy accumulation curve with frequency. The results show that the record energy accumulation curve is a steep rise curve, 80% of total energy of the vertical ground motion is concentrated on the 2.5-15Hz, while the horizontal is mainly concentrated on the 2-11Hz. An improved stochastic finite-fault method is proposed by multiplying an amplification factor in some frequency. The results show that multiplying an amplification factor, the simulated acceleration energy accumulation curve matches to the record acceleration energy accumulation curve, and the peak of simulated acceleration response spectrum tends to the record acceleration value.

scholarly journals Effects of finite source rupture on landslide triggering: The 2016 <i>M<sub>W</sub></i> 7.1 Kumamoto earthquake

2018 ◽  
Author(s):  
Sebastian von Specht ◽  
Ugur Ozturk ◽  
Georg Veh ◽  
Fabrice Cotton ◽  
Oliver Korup
Keyword(s):  
Radiation Pattern ◽  
Ground Motion ◽  
Low Frequency ◽  
New Physics ◽  
Rupture Directivity ◽  
Ground Shaking ◽  
Kumamoto Earthquake ◽  
Directivity Effect ◽  
Seismic Rupture ◽  
Landslide Distribution

Abstract. The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wavefield surrounding the fault during an earthquake. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (MW 7.1) in central Kyūshū (Japan). Although the distribution of some 1,500 earthquake-triggered landslides as function of rupture distance is consistent with the observed Arias intensity, the landslides are more concentrated to the northeast of the southwest-northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors can sufficiently explain the landslide distribution or orientation (aspect), although the landslide headscarps coincide with elevated hillslope inclination and MAF. We propose a new physics-based ground motion model that accounts for the seismic rupture effects, and demonstrate that the low-frequency seismic radiation pattern consistent with the overall landslide distribution. The spatial landslide distribution is primarily influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies

Earthquake time histories compatible with the 2005 National building code of Canada uniform hazard spectrum

2009 ◽  
Vol 36 (6) ◽  
pp. 991-1000 ◽  
Author(s):  
Gail M. Atkinson
Keyword(s):  
Ground Motions ◽  
Time History ◽  
Building Code ◽  
Site Condition ◽  
Period Range ◽  
Uniform Hazard Spectrum ◽  
Finite Fault ◽  
Time Histories ◽  
Finite Fault Method ◽  
Site Classes

The seismic design provisions of the 2005 National building code of Canada (NBCC) (NRC 2005) describe earthquake ground motions for which structures are to be designed in terms of a uniform hazard spectrum (UHS) having a 2% chance of being exceeded in 50 years. The “target” UHS depends on location and site condition, where site condition is described by a classification scheme based on the time-averaged shear-wave velocity in the top 30 m of the deposit. For some applications, such as dynamic analysis by time history methods, it is useful to have time histories that represent the types of earthquake motions expected and match the target UHS from the NBCC over some prescribed period range. In this study, the stochastic finite-fault method is used to generate earthquake time histories that may be used to match the 2005 NBCC UHS for a range of Canadian sites. Records are provided for site classes A, C, D, and E. They are freely available at www.seismotoolbox.ca .

Locating Schumann Resonant Frequencies on a Single Particle Radiation Patterns Using Golden Ratio Spiral and Octave Relationship of Schumann Points.

2021 ◽  
Author(s):  
Mert Yucemoz
Keyword(s):  
Radiation Pattern ◽  
Single Particle ◽  
High Frequency ◽  
Numerical Models ◽  
Golden Ratio ◽  
Lightning Discharge ◽  
Low Frequency ◽  
Radiation Patterns ◽  
Particle Radiation ◽  
Schumann Resonances

&lt;p&gt;Although lightning discharge is not the only source or only physical phenomenon that affects the Schumann resonances, they have the highest contribution to the Schumann resonances oscillating between the ground the ionosphere. Schumann resonances are predicted through several different numerical models such as the transmission-line matrix model or partially uniform knee model. This contribution reports a different prediction method for Schumann resonances derived from the first principle of fundamental physics combining both particle radiation patterns and the mathematical concept of the Golden ratio. This prediction allows the physical understanding of where Schumann resonances originate from radiation emitted by a particle that involves many frequencies that are not related to Schumann resonances. In addition, this method allows predicting the wave propagation direction of each frequency value in the Schumann frequency spectrum. Particles accelerated by lightning leader tip electric fields are capable of contributing most of the Schumann resonances. The radiation pattern of a single particle consists of many frequencies. There are only specific ones within this pattern that contribute to the Schumann radiation. The vast majority of Schumann resonances distribute quite nicely obeying the Golden ratio interval. This property, used in conjunction with the full single-particle radiation patterns, also revealed that high-frequency forward-backward peaking radiation patterns, as well as low-frequency radiation patterns, can contribute to Schumann resonances. This method allows to locate them on the full radiation pattern. A theoretical analysis using the Golden ratio spiral, predict that there are more Schumann resonances in the high-frequency forward-backward peaking radiation pattern of a relativistic particle than low-frequency dipole radiation pattern. Extending the idea to an octave that identifies the identical sounding notes with different frequencies in standing waves. By knowing the value of the initial Schumann resonant frequency, this method allows us to predict the magnitude of other Schumann resonances on the radiation pattern of a single accelerated charged particle conveniently. In addition, it also allows us to find and match Schumann resonances that are on the same radiation lobe, which is named electromagnetic Schumann octaves. Furthermore, it is important to find Schumann octaves as they propagate in the same direction and have a higher likelihood of wave interference.&lt;/p&gt;

Ground-Motion Simulation for the 2008 Wenchuan, China, Earthquake Using the Stochastic Finite-Fault Method

2010 ◽  
Vol 100 (5B) ◽  
pp. 2476-2490 ◽  
Author(s):  
H. Ghasemi ◽  
Y. Fukushima ◽  
K. Koketsu ◽  
H. Miyake ◽  
Z. Wang ◽  
...  
Keyword(s):  
Ground Motion ◽  
Motion Simulation ◽  
Ground Motion Simulation ◽  
Finite Fault ◽  
China Earthquake ◽  
Finite Fault Method

scholarly journals Effects of finite source rupture on landslide triggering: the 2016 <i>M</i><sub>w</sub> 7.1 Kumamoto earthquake

Solid Earth ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 463-486 ◽  
Author(s):  
Sebastian von Specht ◽  
Ugur Ozturk ◽  
Georg Veh ◽  
Fabrice Cotton ◽  
Oliver Korup
Keyword(s):  
Radiation Pattern ◽  
Ground Motion ◽  
Low Frequency ◽  
New Physics ◽  
Rupture Directivity ◽  
Ground Shaking ◽  
Kumamoto Earthquake ◽  
Directivity Effect ◽  
Seismic Rupture ◽  
Landslide Distribution

Abstract. The propagation of a seismic rupture on a fault introduces spatial variations in the seismic wave field surrounding the fault. This directivity effect results in larger shaking amplitudes in the rupture propagation direction. Its seismic radiation pattern also causes amplitude variations between the strike-normal and strike-parallel components of horizontal ground motion. We investigated the landslide response to these effects during the 2016 Kumamoto earthquake (Mw 7.1) in central Kyushu (Japan). Although the distribution of some 1500 earthquake-triggered landslides as a function of rupture distance is consistent with the observed Arias intensity, the landslides were more concentrated to the northeast of the southwest–northeast striking rupture. We examined several landslide susceptibility factors: hillslope inclination, the median amplification factor (MAF) of ground shaking, lithology, land cover, and topographic wetness. None of these factors sufficiently explains the landslide distribution or orientation (aspect), although the landslide head scarps have an elevated hillslope inclination and MAF. We propose a new physics-based ground-motion model (GMM) that accounts for the seismic rupture effects, and we demonstrate that the low-frequency seismic radiation pattern is consistent with the overall landslide distribution. Its spatial pattern is influenced by the rupture directivity effect, whereas landslide aspect is influenced by amplitude variations between the fault-normal and fault-parallel motion at frequencies <2 Hz. This azimuth dependence implies that comparable landslide concentrations can occur at different distances from the rupture. This quantitative link between the prevalent landslide aspect and the low-frequency seismic radiation pattern can improve coseismic landslide hazard assessment.

scholarly journals Comparison of Analysis and Design of Regular and Irregular Configuration of Multi Story Building in Seismic Zones

2021 ◽  
Vol 9 (8) ◽  
pp. 2395-2412
Author(s):  
Mohd. Swaliheen
Keyword(s):  
Natural Frequency ◽  
Ground Motion ◽  
Low Frequency ◽  
Time History ◽  
Regular Structure ◽  
Time History Analysis ◽  
Analysis And Design ◽  
Regular Structures ◽  
Irregular Structure ◽  
History Analysis

Abstract: This paper is concerned with the effects of various vertical irregularities on the seismic response of a structure. The objective of the project is to carry out Response spectrum analysis (RSA) and Time history Analysis (THA) of vertically irregular RC building frames and to carry out the ductility based design using IS 13920 corresponding to Equivalent static analysis and Time history analysis. Comparison of the results of analysis and design of irregular structures with regular structure was done. The scope of the project also includes the evaluation of response of structures subjected to high, low and intermediate frequency content earthquakes using Time history analysis. Three types of irregularities namely mass irregularity, stiffness irregularity and vertical geometry irregularity were considered. According to our observation, the storey shear force was found to be maximum for the first storey and it decreases to minimum in the top storey in all cases. The mass irregular structures were observed to experience larger base shear than similar regular structures. The stiffness irregular structure experienced lesser base shear and has larger inter-storey drifts. The absolute displacements obtained from time history analysis of geometry irregular structure at respective nodes were found to be greater than that in case of regular structure for upper stories but gradually as we moved to lower stories displacements in both structures tended to converge. . Lower stiffness results in higher displacements of upper stories. In case of a mass irregular structure, time history analysis gives slightly higher displacement for upper stories than that in regular structures whereas as we move down lower stories show higher displacements as compared to that in regular structures. When time history analysis was done for regular as well as stiffness irregular structure, it was found that displacements of upper stories did not vary much from each other but as we moved down to lower stories the absolute displacement in case of soft storey were higher compared to respective stories in regular structure. Tall structures were found to have low natural frequency hence their response was found to be maximum in a low frequency earthquake. It is because low natural frequency of tall structures subjected to low frequency earthquake leads to resonance resulting in larger displacements. If a high rise structure (low natural frequency)is subjected to high frequency ground motion then it results in small displacements. Similarly, if a low rise structure (high natural frequency) is subjected to high frequency ground motion it results in larger displacements whereas small displacements occur when the high rise structure is subjected to low frequency ground motion.

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