Simulation of Short Period Lg, Expansion of Three-Dimensional Source Simulation Capabilities and Simulation of Near-Field Ground Motion from the 1971 San Fernando, California, Earthquake

1981 ◽  
Author(s):  
T. C. Bache ◽  
H. J. Swanger ◽  
B. Shkoller ◽  
S. M. Day
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Three Dimensional ◽  
Short Period ◽  
San Fernando

Strain, tilt, and rotation associated with strong ground motion in the vicinity of earthquake faults

1982 ◽  
Vol 72 (5) ◽  
pp. 1717-1738 ◽  
Author(s):  
Michel Bouchon ◽  
Keiiti Aki
Keyword(s):  
Ground Motion ◽  
Rotational Velocity ◽  
Near Field ◽  
Strike Slip ◽  
Phase Velocities ◽  
Crustal Structures ◽  
Time Histories ◽  
San Fernando ◽  
Earthquake Faults ◽  
Strong Ground

abstract In the absence of near-field records of differential ground motion induced by earthquakes, we simulate the time histories of strain, tilt, and rotation in the vicinity of earthquake faults embedded in layered media. We consider the case of both strike-slip and dip-slip fault models and study the effect of different crustal structures. The maximum rotational motion produced by a buried 30-km-long strike-slip fault with slip of 1 m is of the order of 3 × 10−4 rad while the corresponding rotational velocity is about 1.5 × 10−3 rad/sec. A simulation of the San Fernando earthquake yields maximum longitudinal strain and tilt a few kilometers from the fault of the order of 8 × 10−4 and 7 × 10−4 rad. These values being small compared to the amplitude of ground displacement, the results suggest that most of the damage occurring in earthquakes is caused by translation motions. We also show that strain and tilt are closely related to ground velocity and that the phase velocities associated with strong ground motions are controlled by the rupture velocity and the basement rock shearwave velocity.

scholarly journals The February 9, 1971 San Fernando earthquake: A study of source finiteness in teleseismic body waves

1978 ◽  
Vol 68 (1) ◽  
pp. 1-29 ◽  
Author(s):  
Charles A. Langston
Keyword(s):  
Near Field ◽  
Dislocation Line ◽  
Strong Motion ◽  
Body Waves ◽  
P Waves ◽  
Long Period ◽  
Short Period ◽  
Wave Forms ◽  
San Fernando ◽  
The Time Domain

abstract Teleseismic P, SV, and SH waves recorded by the WWSS and Canadian networks from the 1971 San Fernando, California earthquake (ML = 6.6) are modeled in the time domain to determine detailed features of the source as a prelude to studying the near and local field strong-motion observations. Synthetic seismograms are computed from the model of a propagating finite dislocation line source embedded in layered elastic media. The effects of source geometry and directivity are shown to be important features of the long-period observations. The most dramatic feature of the model is the requirement that the fault, which initially ruptured at a depth of 13 km as determined from pP-P times, continuously propagated toward the free surface, first on a plane dipping 53°NE, then broke over to a 29°NE dipping fault segment. This effect is clearly shown in the azimuthal variation of both long period P- and SH-wave forms. Although attenuation and interference with radiation from the remainder of the fault are possible complications, comparison of long- and short-period P and short-period pP and P waves suggest that rupture was initially bilateral, or, possibly, strongly unilateral downward, propagating to about 15 km depth. The average rupture velocity of 1.8 km/sec is well constrained from the shape of the long-period wave forms. Total seismic moment is 0.86 × 1026 dyne-cm. Implications for near-field modeling are drawn from these results.

High-Resolution Seismic Hazard Analysis in a Complex Geological Configuration: The Case of the Sulmona Basin in Central Italy

2014 ◽  
Vol 30 (4) ◽  
pp. 1801-1824 ◽  
Author(s):  
Manuela Villani ◽  
Ezio Faccioli ◽  
Mario Ordaz ◽  
Marco Stupazzini
Keyword(s):  
High Resolution ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Hazard Analysis ◽  
Near Field ◽  
Central Italy ◽  
Three Dimensional ◽  
Spectral Element ◽  
Seismic Wave Propagation ◽  
Novel Approach

This work proposes a novel approach for probabilistic seismic hazard analyses (PSHA) in the near field of active earthquake faults, in which deterministically computed ground motion scenarios, replacing empirically predicted ground motion values, are introduced. In fact, the databases of most ground motion prediction equations (GMPEs) tend to be insufficiently constrained at short distances and data may only partially account for the rupture process, seismic wave propagation and three-dimensional (3-D) complex configurations. Hence, herein, 3-D numerical simulations of a Mw = 6.4 earthquake rupture of the Sulmona fault in Central Italy, are carried out through the spectral element code GeoELSE ( f < 2.5 Hz), and the results are introduced in a PSHA, exploiting the capabilities of CRISIS2008 code. The SH results obtained highlight the combined effects of site, basin, and topographic features, and provide a “high-resolution” representation of the hazard in the Sulmona Basin, particularly at long periods. Such representation is expected to be more realistic than those based simply on a GMPE.

Simplified Method of Isolated Structure Collapse Capacity Part, (I): Ground Motion Intensity Measure

2013 ◽  
Vol 275-277 ◽  
pp. 1466-1470
Author(s):  
Yang Liu ◽  
Wen Guang Liu ◽  
Wen Fu He ◽  
Qiao Rong Yang
Keyword(s):  
Correlation Coefficient ◽  
Ground Motion ◽  
Ground Motions ◽  
Near Field ◽  
Far Field ◽  
Intensity Measure ◽  
Maximum Deformation ◽  
Average Value ◽  
Short Period ◽  
Ground Motion Intensity Measure

The equivalent velocity spectrum as a new ground motion intensity measure (IM) characterization parameter is proposed in this paper. 44 far field ground motions and 20 near-field high-speed pulse seismic waves were used for single-degree-freedom (SDOF) nonlinear time history analysis, respectively. The correlations between five IMs and maximum deformation for SDOF at various periods and different yield coefficients were analyzed. The results show that for the structures with medium-to-long period, the correlation coefficient average value of the proposed equivalent speed and maximum deformation is more than 0.6, and maximum of those is more than 0.9. The correlation coefficient average value by using the proposed equivalent speed under far field ground motions is more than those under near field ground motions. The P-delta effect on the correlation coefficients between proposed IM for the structures with medium-to-short period is significant

scholarly journals Evidence for Unusually Strong Near-field Ground Motion on the Hanging Wall of the San Fernando Fault during the 1971 Earthquake

1998 ◽  
Vol 69 (6) ◽  
pp. 524-531 ◽  
Author(s):  
C. R. Allen ◽  
J. N. Brune ◽  
L. S. Cluff ◽  
A. G. Barrows
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Hanging Wall ◽  
San Fernando

Stress estimates for the San Fernando, California, earthquake of February 9, 1971: Main event and thirteen aftershocks

1972 ◽  
Vol 62 (3) ◽  
pp. 721-750 ◽  
Author(s):  
M. D. Trifunac
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Strong Motion ◽  
Earthquake Ground Motion ◽  
The North ◽  
Field Evidence ◽  
North Eastern ◽  
San Fernando ◽  
And Migration ◽  
Stress Drops

Abstract The strong earthquake ground motion recorded in the center of and above the fault plane is combined with field evidence of faulting and instrumental studies of aftershocks to deduce stresses during and after the San Fernando earthquake of February 9, 1971. Stress computations based on Brune's near-field, shear-wave spectra, peak velocity of ground motion, energy calculated from the strong-motion record, and a model of circular dislocation give mutually consistent stress estimates, which suggest that the effective stress operating during the earthquake was approximately 100 bars, while during the earthquake it dropped several tens of bars. The energy of the main event is estimated to be 1022 dyne cm. Thirteen aftershocks, recorded during the first 6 min, were associated with stress drops ranging from 10 to 500 bars, these events clustering along the north-eastern end of the dislocation surface. The strong-motion accelerograms provide invaluable data for detailed investigations of the pattern of earthquake energy release during and immediately after an earthquake. Used for the first time in this study, strong-motion accelerograms gave an excellent picture of stress history and migration of seismic activity during the first 6 min.

Calculation of ground motion in a three-dimensional model of the 1966 Parkfield earthquake

1976 ◽  
Vol 66 (2) ◽  
pp. 405-423
Author(s):  
N. A. Levy ◽  
A. K. Mal
Keyword(s):  
Surface Waves ◽  
Ground Motion ◽  
Near Field ◽  
Three Dimensional ◽  
Vertical Component ◽  
Elastic Half Space ◽  
The Body ◽  
Body Waves ◽  
Three Dimensional Model ◽  
Ground Displacements

abstract Near-field ground displacements are calculated from an earthquake source in a homogeneous, elastic half-space. An analytical formulation of the problem is presented that requires no physical approximations except at the source. A model of the source is constructed by retaining the essential kinematic character of the faulting process. A computer program is developed to calculate ground motion from an assumed model of the 1966 Parkfield, California earthquake. Favorable agreement is obtained between the theoretically computed ground displacements and those derived from the recorded accelerations. The relative contributions of the body waves and surface waves to the displacement field are examined. The results indicate that a significant portion of near-field motion may consist of surface waves, especially in the vertical component of the ground motion.

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