Source model of the 1995 Hyogo-Ken Nanbu earthquake and simulation of near-source ground motion

1998 ◽  
Vol 88 (2) ◽  
pp. 400-412
Author(s):  
Katsuhiro Kamae ◽  
Kojiro Irikura
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Ground Motions ◽  
Source Region ◽  
Source Model ◽  
Rupture Directivity ◽  
Strong Ground Motions ◽  
Starting Point ◽  
Initial Source ◽  
Strong Ground

Abstract The 1995 Hyogo-Ken Nanbu earthquake struck the heavily populated Kobe and adjacent cities in western Japan. More than 6400 people were killed, and more than 150,000 buildings were destroyed. The characteristics of mainshock ground motions in the heavily damaged area are needed to understand how buildings and bridges performed and why they reached failure. Unfortunately, very few strong ground motions were recorded in the heavily damaged area during the mainshock. In this study, we attempt to estimate mainshock ground motions by using the empirical Green's function method (EGF method). First, we assume an initial source model with the asperities based on the rupture process obtained by inversion of strong-ground-motion records. For simplicity, we consider each asperity as a subevent with uniform stress drop in a finite extent. Then, the initial model was improved by matching the synthetic and observed ground motions using a trial-and-error procedure. The final model consists of three subevents: subevent 1 with stress drop of 163 bars, under the Akashi Strait around the rupture starting point; subevent 2 with stress drop of 86 bars, under the Nojima Fault in Awaji Island; and subevent 3 with stress drop of 86 bars, under Kobe. Finally, we estimate strong ground motions using aftershock records at sites where the mainshock was not recorded. The near-source motions in Kobe synthesized with the best-fit model are characterized by two large pulses with a duration of 1 to 3 sec. The pulses are caused by forward rupture directivity effects from subevents 1 and 3. Peak horizontal acceleration and velocity of the synthesized motions at the heavily damaged sites are about 1000 cm/sec2 and 130 cm/sec, respectively, while those at a rock site in the near-source region are about 300 cm/sec2 and 60 cm/sec.

Empirical Relationships for Frequency Content Parameters of Earthquake Ground Motions

2004 ◽  
Vol 20 (1) ◽  
pp. 119-144 ◽  
Author(s):  
Ellen M. Rathje ◽  
Fadi Faraj ◽  
Stephanie Russell ◽  
Jonathan D. Bray
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Earthquake Ground Motion ◽  
Rupture Directivity ◽  
Frequency Content ◽  
Deep Soil ◽  
Empirical Relationships ◽  
Strong Ground Motions ◽  
Site Classes ◽  
Strong Ground

The frequency content of an earthquake ground motion is important because it affects the dynamic response of earth and structural systems. Four scalar parameters that characterize the frequency content of strong ground motions are (1) the mean period (Tm), (2) the average spectral period (Tavg), (3) the smoothed spectral predominant period (To), and (4) the predominant spectral period (Tp). Tm and Tavg distinguish the low frequency content of ground motions, while To is affected most by the high frequency content. Tp does not adequately describe the frequency content of a strong ground motion and is not recommended. Empirical relationships are developed that predict three parameters (Tm, Tavg, and To) as a function of earthquake magnitude, site-to-source distance, site conditions, and rupture directivity. The relationships are developed from a large strong-motion database that includes recorded motions from the recent earthquakes in Turkey and Taiwan. The new relationships update those previously developed by the authors and others. The results indicate that three site classes, which distinguish between rock, shallow soil, and deep soil, provide a better prediction of the frequency content parameters and smaller standard error terms than conventional “rock” and “soil” site classes. Forward directivity significantly increases the frequency content parameters, particularly Tm and To, at distances less than 20 km. Each of the frequency content parameters can be predicted with reasonable accuracy, but Tm is the preferred because it best distinguishes the frequency content of strong ground motions.

The Simulation of Strong Ground Motion Using Empirical Green Function and Stochastic Method for Southern Taiwan Area

2018 ◽  
Author(s):  
Tsung-Jen Teng ◽  
Pei-Ting Chen ◽  
Ting-Wei Chang ◽  
Yuan-Sen Yang ◽  
Chien-Kuo Chiu ◽  
...  
Keyword(s):  
Green Function ◽  
Ground Motion ◽  
Strong Ground Motion ◽  
Ground Motions ◽  
Large Earthquake ◽  
Green Function Method ◽  
Strong Ground Motions ◽  
Empirical Green Function ◽  
Southern Taiwan ◽  
Strong Ground

This study presents strong ground motion simulation methods for the future fragility study of a power plant in Southern Taiwan. The modified stochastic method and empirical Green function method are utilized to synthesize the strong ground motions of specific events. A modified physical random function model of strong ground motions for specific sites and events is presented in this study with verification of sample level. Based on the special models of the source, path, and local site, the random variables of the physical random function of strong ground motions is obtained. The inverse Fourier transform is used to simulate strong ground motions. For the empirical Green function method, the observed site records from small earthquake events occurring around the source area of a large earthquake are collected to simulate the broadband strong ground motion from a large earthquake event. Finally, an application of proposed two simulated methods of this study for simulating the ground motion records of Nishi-Akashi Station at 1995 Kobe earthquake and 2006 Southern Taiwan PingDong earthquake are presented.

On the Seismic Response of the Faculty of Architecture and Engineering Building at Tohoku University

2016 ◽  
Vol 32 (1) ◽  
pp. 523-545 ◽  
Author(s):  
Ying Wang ◽  
Enrique Villalobos ◽  
Santiago Pujol ◽  
Hamood Al-Washali ◽  
Kazuki Suzuki ◽  
...  
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Structural Damage ◽  
Ground Motions ◽  
Strong Ground Motions ◽  
First Motion ◽  
Strong Ground

The Faculty of Architecture and Engineering Building at Tohoku University survived two strong ground motions. This is not surprising because the structure was stiff and strong. What is surprising is that the first ground motion did not cause severe structural damage but the second one caused so much structural damage that the building had to be evacuated and demolished. The damage occurred despite two key facts: (1) the intensities of the mentioned ground motions are understood to have been similar and (2) the building was strengthened after the first motion (and before the second) following stringent standards.

scholarly journals The near-source ground motion of the 6 August 1979 Coyote Lake, California, earthquake

1983 ◽  
Vol 73 (1) ◽  
pp. 201-218
Author(s):  
Hsui-Lin Liu ◽  
Donald V. Helmberger
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Personal Communication ◽  
Source Model ◽  
Total Moment ◽  
Motion Data ◽  
Rupture Length ◽  
Finite Fault ◽  
Source Data ◽  
Strong Ground

abstract A finite fault striking N24°W and extending to a depth of 10 km is proposed to explain the strong ground motion data for the 6 August 1979 Coyote Lake, California, earthquake (ML = 5.9). Our source model suggests that right-lateral faulting initiated at a depth of 8 km and ruptured toward the south with a velocity of 2.8 km/sec. This unilateral rupture can explain the large displacement recorded south of the epicenter. However, the waveform coherency across an array south and southwest of the epicenter suggests that the rupture length is less than 6 km. The maximum dislocation is about 120 cm in a small area near the hypocenter, and the total moment is estimated to be 3.5 ×1024 dyne-cm. An abrupt stopping phase which corresponds to a deceleration of right-lateral motion can explain the high peak acceleration recorded at array station 6. The stress drop in the hypocentral area is about 140 bars; the average stress drop over the entire rupture surface is 30 bars. The preferred finite-source model can predict the Pn1 waveforms and the beginning features in the teleseismic seismograms. No clear arrivals can be observed in the near-source data for the possible second and third smaller events suggested by Nabelek (personal communication).

Simplified R-Factor Relationships for Strong Ground Motions

2003 ◽  
Vol 19 (1) ◽  
pp. 25-45 ◽  
Author(s):  
Isabel Cuesta ◽  
Mark A. Aschheim ◽  
Peter Fajfar
Keyword(s):  
Ground Motion ◽  
Ground Motions ◽  
Structural Systems ◽  
Code Design ◽  
Frequency Content ◽  
Design Spectrum ◽  
Strong Ground Motions ◽  
R Factor ◽  
N2 Method ◽  
Strong Ground

Recent studies have demonstrated the need to consider the ground motion frequency content in the development and use of R−μ−T relationships. Results from two different approaches to determining these relationships are unified in the present paper. Two bilinear R−μ−T/Tg relationships are recommended for most strong ground motions and structural systems. One is more accurate, while the other, more conservative relationship is used in FEMA 273, ATC-32, and the simple version of the N2 method. Both relationships are indexed by the characteristic period of the ground motion, Tg. Simple methods to determine Tg from smoothed design spectra and recorded ground motions are provided. Neither recommended relationships are applicable to the nearly harmonic ground motions that may be generated at sites containing soft lakebed deposits. An example illustrates the application of these relationships to a code design spectrum in both the acceleration-displacement and yield point spectra formats.

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