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).

A fault model with variable slip duration for the 1989 Loma Prieta, California, earthquake determined from strong-ground-motion data

1996 ◽  
Vol 86 (1A) ◽  
pp. 122-132
Author(s):  
Stephen Horton
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Propagation Rate ◽  
Fault Model ◽  
Fault Surface ◽  
Loma Prieta Earthquake ◽  
Motion Data ◽  
Finite Fault ◽  
Loma Prieta ◽  
Strong Ground

Abstract A finite-fault model with variable slip duration is inferred from strong-ground-motion data for the Loma Prieta earthquake. Unlike previous models, slip duration is found to be consistent with fault width scaling. Slip duration varies between 1 and 6 sec at points along the fault surface with values between 3 and 6 sec, where slip amplitudes obtain or exceed the average slip of 98 cm. Modest high-frequency modifications of the slip function shape greatly enhance the data fit without significantly changing the inferred static offset or rupture characteristics. This model exhibits bilateral rupture with the propagation rate of the main energy release of 3 km/sec or less. The moment is 2.3 × 1026 dyne-cm, and the largest slip amplitudes occur northwest of the hypocenter. The rake varies with position along the fault from dominantly strike slip in the southeast to dominantly reverse slip in the northwest.

On strong ground motion estimates based on models of the radiated spectrum

1985 ◽  
Vol 75 (3) ◽  
pp. 641-649
Author(s):  
J. Enrique Luco
Keyword(s):  
Ground Motion ◽  
Stress Drop ◽  
Peak Ground Acceleration ◽  
Strong Ground Motion ◽  
Source Model ◽  
Spectral Model ◽  
Ground Acceleration ◽  
A Value ◽  
Strong Ground ◽  
Good Agreement

Abstract Estimates for peak ground acceleration and velocity were obtained by use of the approach of Hanks and McGuire (1981) and Boore (1983) for a model of the radiated spectrum corresponding to Brune's ω−2 source model modified by an exponentially decreasing function of frequency. This modification was suggested by the work of Anderson and Hough (1984) on spectral amplitudes. For this spectral model, it was found that it is not possible to determine a value for the stress drop parameter such that agreement with data is obtained for both peak accelerations and velocities. This finding contrasts with that of Boore (1983) who found good agreement with data by introducing an artificial cut-off frequency of 15 Hz.

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.

Characteristics of strong ground motion data recorded in the Gubbio sedimentary basin (Central Italy)

2006 ◽  
Vol 5 (1) ◽  
pp. 27-43 ◽  
Author(s):  
F. Pacor ◽  
D. Bindi ◽  
L. Luzi ◽  
S. Parolai ◽  
S. Marzorati ◽  
...  
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Sedimentary Basin ◽  
Central Italy ◽  
Motion Data ◽  
Strong Ground

Verification of attenuation models based on strong ground motion data in Northern Thailand

2020 ◽  
Vol 133 ◽  
pp. 106145
Author(s):  
Weeradetch Tanapalungkorn ◽  
Lindung Zalbuin Mase ◽  
Panon Latcharote ◽  
Suched Likitlersuang
Keyword(s):  
Ground Motion ◽  
Strong Ground Motion ◽  
Northern Thailand ◽  
Motion Data ◽  
Attenuation Models ◽  
Strong Ground

High-Frequency Spectral Decay Characteristics of Seismic Records of Inland Crustal Earthquakes in Japan: Evaluation of the fmax and κ Models

2020 ◽  
Vol 110 (2) ◽  
pp. 452-470
Author(s):  
Masato Tsurugi ◽  
Reiji Tanaka ◽  
Takao Kagawa ◽  
Kojiro Irikura
Keyword(s):  
Ground Motion ◽  
High Frequency ◽  
Strong Ground Motion ◽  
Cutoff Frequency ◽  
Source Model ◽  
Power Coefficient ◽  
Crustal Earthquakes ◽  
Log Linear ◽  
Large Earthquakes ◽  
Strong Ground

ABSTRACT We examined high-frequency spectral decay characteristics of ground motions for inland crustal earthquakes in Japan, which are important in strong ground motion predictions. We examined 105 earthquakes (Mw 3.3–7.1), including seven large earthquakes (Mw 5.9–7.1). Spectral decay characteristics were accurately evaluated assuming the ω-squared source model and using two approaches: the fmax model (commonly used in Japan), described by the cutoff frequency fmax and the power coefficient of spectral decay s, and the κ model (commonly used in worldwide), the exponential spectral decay model, described by the parameter κ and the specific frequency fE at which a spectrum starts to decrease linearly with increasing frequency in log–linear space. For large earthquakes, we estimated fmax to range from 6.5 to 9.9 Hz and s from 0.78 to 1.60 in the fmax model, and κ to range from 0.014 to 0.051 s and fE from 2 to 4.5 Hz in the κ model. In both approaches, we found that the spectral decay characteristics are regionally dependent. fmax in the fmax model and fE in the κ model tended to be smaller for large earthquakes than for moderate and small earthquakes, clearly demonstrating a seismic moment dependency. We confirmed positive correlations between equivalent parameters of the two approaches, that is, between s and κ and between fmax and fE. Moreover, we found that both approaches are appropriate for evaluating spectral decay characteristics, as long as the spectral decay parameters are appropriately evaluated by comparison with observed spectra. We examined the effects of the spectral decay characteristics on strong ground motion predictions, and demonstrated that simulated motions corrected using the fmax model and those corrected using the κ model are almost the same. The results presented in this article contribute to improving predictions of high-frequency strong ground motion.

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