Introduction: Heart of the Transverse Ranges Geology and Tectonics of the San Fernando Valley and East Ventura Basin

2001 ◽  
Author(s):  
Tom Wright
Keyword(s):  
Transverse Ranges ◽  
San Fernando ◽  
San Fernando Valley ◽  
Ventura Basin

scholarly journals Geological Structure of the Sylmar Basin: Implications for Slip Distribution Along the Santa Susana/Hospital and Mission Hills Fault System in the San Fernando Valley, CA, U.S.A.

2021 ◽  
Vol 8 ◽  
Author(s):  
Yuval Levy ◽  
Thomas Rockwell ◽  
Shant Minas ◽  
Alex Hughes ◽  
Dylan Rood
Keyword(s):  
Large Diameter ◽  
Slip Rate ◽  
Geological Structure ◽  
Fault System ◽  
Transverse Ranges ◽  
Blind Thrust ◽  
Fault Propagation Fold ◽  
San Fernando ◽  
San Fernando Valley ◽  
Structural Relief

We developed a forward model using the Trishear module in MOVE to better understand the structure of the northwestern San Fernando Valley and the relationship among the Santa Susana, Hospital, Mission Hills and Northridge Hills faults. This study was motivated by the 1971 San Fernando earthquake and previous work that inferred a high slip rate on the Santa Susana fault, which is in apparent contrast to the lack of significant geomorphic expression of the fault in the Sylmar Basin region. We trenched the Mission Hills anticline from the crest to the base of slope and demonstrate that the Mission Hills anticline is an actively growing fault propagation fold. The associated thrust tip is either deeper than 15 m or sufficiently far to the south that the fault was not encountered in large diameter borings, but the minimum structural relief across the Mission Hills fault since the late Pleistocene is on the order of 37 m, suggesting a minimum uplift rate of 0.5 mm/yr. Our work presents a structural analysis that demonstrates how the Santa Susana fault system evolved in time, with the frontal thrust progressively migrating southward to the Mission Hills fault, and farther south to the Northridge Hills blind thrust. The progression of faulting towards the direction of vergence is compatible with the observed thrust front migration in the western Transverse Ranges of California, and other trust belts around the world.

Interpretation of significant ground-response and structure strong motions recorded during the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S231-S246 ◽  
Author(s):  
A. F. Shakal ◽  
M. J. Huang ◽  
R. B. Darragh
Keyword(s):  
Flexible Structures ◽  
Northridge Earthquake ◽  
Moment Frame ◽  
Ground Response ◽  
Short Period ◽  
Frame Buildings ◽  
Story Drift ◽  
San Fernando ◽  
San Fernando Valley ◽  
The Moment

Abstract Some of the largest accelerations and velocities ever recorded at ground-response and structural sites occurred during the Northridge earthquake. These motions are greater than most existing attenuation models would have predicted. Although the motions are large, the correspondence between measured acceleration and damage requires further study, since some sites with high acceleration experienced only moderate damage. Also, some peak vertical accelerations were larger than the horizontal, but in general, they are smaller and fit the pattern observed in previous earthquakes. Strong-motion records processed to date show significant differences in acceleration and velocity waveforms and amplitudes across the San Fernando Valley. Analysis of processed data from several buildings in the San Fernando Valley indicates that short-period buildings such as shear-wall buildings experienced large forces and relatively low inter-story drift during the Northridge earthquake. However, long-period (1 to 5 sec) steel or concrete moment-frame buildings experienced large inter-story drift. For this earthquake, accelerations did not always amplify from base to roof for flexible structures like the moment-frame buildings, but the displacements were always larger at the roof. The drifts at many of the moment-frame buildings were larger than the drift limit for working stress design in the building code. The records from a base-isolated building indicate that high-frequency motion was reduced significantly by the isolators. The isolators deformed about 3.5 cm, which is much less than the design displacement. The records from a parking structure show important features of the seismic response of this class of structure.

scholarly journals Maps showing historic flooding in the San Fernando Valley, California, 1934 to 1956

1981 ◽  
Author(s):  
Ellen J. King ◽  
J.C. Tinsley ◽  
Ronald F. Preston
Keyword(s):  
San Fernando ◽  
San Fernando Valley
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