scholarly journals Ground-motion variability resulting from the January 17, 1994, M = 6.6 Northridge earthquake at the interchange between highways 14 and I-5 in the northern San Fernando Valley

1994 ◽  
Author(s):  
L. Hutchings ◽  
S. Jarpe ◽  
P. Kasameyer ◽  
D. McCallen ◽  
F. Heuze ◽  
...  
Keyword(s):  
Ground Motion ◽  
Northridge Earthquake ◽  
Ground Motion Variability ◽  
San Fernando ◽  
San Fernando Valley

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.

Seismology

1995 ◽  
Vol 11 (2_suppl) ◽  
pp. 1-12
Keyword(s):  
Los Angeles ◽  
Seismic Hazard ◽  
Focal Depth ◽  
High Rate ◽  
Northridge Earthquake ◽  
Los Angeles Basin ◽  
San Fernando ◽  
Northern Edge ◽  
San Fernando Valley ◽  
The Moment

The Northridge earthquake occurred on January 17, 1994, at 4:31 a.m. Pacific Standard Time. The hypocenter was about 32 km west-northwest of Los Angeles in the San Fernando Valley at a relatively deep focal depth of 19 km. The moment magnitude for the earthquake is Mw6.7. The earthquake occurred on a south-southwest dipping thrust ramp beneath the San Fernando Valley and, thus, reemphasized the seismic hazard of concealed faults in the greater Los Angeles region. The Northridge earthquake also indicates a continuing high rate of seismicity along the northern edge of the Los Angeles basin.

Fire-Related Aspects

1995 ◽  
Vol 11 (2_suppl) ◽  
pp. 419-435 ◽  
Keyword(s):  
Los Angeles ◽  
Fire Department ◽  
Northridge Earthquake ◽  
Mutual Aid ◽  
Fire Departments ◽  
Santa Monica ◽  
San Fernando ◽  
Wide Scale ◽  
San Fernando Valley ◽  
Alternative Water

The Northridge earthquake caused high shaking intensities for several million persons in the northern Los Angeles region, centered in the San Fernando Valley. Fire protection for the heavily damaged area is furnished primarily by Los Angeles City Fire Department and, to a lesser extent, Los Angeles County, Santa Monica, and other departments. The earthquake resulted in about 110 fires, about 80% of which were structure fires. Of these, most were in single-or multi-family dwellings. All of the initial fires were out before noon despite impaired communications, wide-scale failure of firefighting water supply in large parts of the San Fernando Valley, and other problems. Alternative water supplies, such as backyard swimming pools, were employed in some cases. Mutual aid was requested by fire departments in the affected area, but resources from outside the Los Angeles metropolitan area were not required.

scholarly journals Seismic hazard analysis for Sutami Dam using probabilistic method

2019 ◽  
Vol 276 ◽  
pp. 05012
Author(s):  
Yusep Muslih Purwana ◽  
Raden Harya D.H.I ◽  
Bambang Setiawan ◽  
Ni’am Aulawi
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Return Period ◽  
Hazard Analysis ◽  
Probabilistic Method ◽  
Northridge Earthquake ◽  
Ground Acceleration ◽  
Motion Data ◽  
San Fernando ◽  
Over 40 Years

One of the largest structures in Malang is Sutami dam. It was built in 1964 to 1973 and began to be operated in 1977. Considering the age of the dam which is over 40 years and the high risk of earthquake in this area, it is necessary to analyze its seismic hazard using an updated data. The probablilistic seismic hazard analyses (PSHA) was employed to obtain peak ground acceleration (PGA). The deagregation was conducted to obtain the most influencing magnitudes (M) and and distance (R) values affecting the dam. The result indicates that the area of the dam has the PGA of 0.261 for 500 years return period, 0.41 for 2500 years return period and 0.586 for 10,000 years return period of eartquakes. The magnitude of 5.93-6.17 for the distance of 22-44 km are considered as the most influencing earthquake for the dam. Due to the lack of ground motion data for Sutami dam, the ground motion from other earthquake might be utilised such as Morgan Hill earthquake 1984, Whittier Narrow earthquake 1987, Chalfant Valley earthquake 1986, Georgia USSR earthquake 1991, Northridge earthquake 1994, or San Fernando earthquake 1971.

An autoethnographic account of urban restructuring and neighborhood change in Los Angeles’ San Fernando Valley

2019 ◽  
Vol 27 (3) ◽  
pp. 379-394 ◽  
Author(s):  
Stefano Bloch
Keyword(s):  
Los Angeles ◽  
Cultural Landscape ◽  
Neighborhood Change ◽  
General Motors ◽  
Northridge Earthquake ◽  
Urban Restructuring ◽  
Time Period ◽  
San Fernando ◽  
San Fernando Valley ◽  
Children Welfare

Suburbs have long been glossed over by critical urbanists for being culturally, even if not spatially, less than urban. In Los Angeles, it is the San Fernando Valley that has received such treatment as scholars have tended toward the metropolitan basin. In this article, I aim to help re-center the San Fernando Valley as a complex and conflictual cultural landscape through an autoethnographic exploration of four moments of urban restructuring in the Panorama City neighborhood. I provide a personal account of how a succession of events – the 1992 LA Riot, 1993 General Motors Plant closure, 1994 Northridge earthquake, and 1996 dismantling of the Aid for Families with Dependent Children welfare program – led to the disruption and partial destruction of a neighborhood. I situate these moments of crisis within the context of a civil gang injunction and outbreak of abject violence during this time period, which further destabilized the neighborhood and informed my own decision to pick up a gun.

Coupled Soil-Structure Interaction Effects of Building Clusters during Earthquakes

2015 ◽  
Vol 31 (1) ◽  
pp. 463-500 ◽  
Author(s):  
Yigit Isbiliroglu ◽  
Ricardo Taborda ◽  
Jacobo Bielak
Keyword(s):  
Ground Motion ◽  
Soil Structure ◽  
Dynamic Properties ◽  
Soil Structure Interaction ◽  
Rigid Base ◽  
Northridge Earthquake ◽  
Structure Interaction ◽  
Building Models ◽  
Building Foundation ◽  
San Fernando

This study addresses the responses of idealized building clusters during earthquakes, their effects on ground motion, and the ways individual buildings interact with the soil and with each other. We simulate the ground motion during the 1994 Northridge earthquake and focus on the coupled responses of multiple simplified building models located within the San Fernando Valley. Numerical results show that the soil-structure interaction (SSI) effects vary with the number and dynamic properties of the buildings, their separation, and their impedance with respect to the soil. These effects appear as: (i) an increased spatial variability of the ground motion; and (ii) significant reductions in the buildings’ base motion at high frequencies, changes in the higher natural frequencies of the building-foundation systems, and variations in the roof displacement, with respect to those of the corresponding rigid-base and single SSI models.

Nonlinear ground-motion amplification by sediments during the 1994 Northridge earthquake

Nature ◽  
10.1038/37586 ◽  
1997 ◽  
Vol 390 (6660) ◽  
pp. 599-602 ◽  
Author(s):  
Edward H. Field ◽  
Paul A. Johnson ◽  
Igor A. Beresnev ◽  
Yuehua Zeng
Keyword(s):  
Ground Motion ◽  
Northridge Earthquake ◽  
Ground Motion Amplification ◽  
1994 Northridge Earthquake

scholarly journals From scenario-based seismic hazard to scenario-based landslide hazard: fast-forwarding to the future via statistical simulations

2021 ◽  
Author(s):  
Luigi Lombardo ◽  
Hakan Tanyas
Keyword(s):  
Ground Motion ◽  
Landslide Susceptibility ◽  
Additive Model ◽  
Landslide Hazard ◽  
Northridge Earthquake ◽  
Ground Acceleration ◽  
Temporal Dimension ◽  
Earthquake Scenario ◽  
The Mean ◽  
Ground Motion Scenarios

AbstractGround motion scenarios exists for most of the seismically active areas around the globe. They essentially correspond to shaking level maps at given earthquake return times which are used as reference for the likely areas under threat from future ground displacements. Being landslides in seismically actively regions closely controlled by the ground motion, one would expect that landslide susceptibility maps should change as the ground motion patterns change in space and time. However, so far, statistically-based landslide susceptibility assessments have primarily been used as time-invariant.In other words, the vast majority of the statistical models does not include the temporal effect of the main trigger in future landslide scenarios. In this work, we present an approach aimed at filling this gap, bridging current practices in the seismological community to those in the geomorphological and statistical ones. More specifically, we select an earthquake-induced landslide inventory corresponding to the 1994 Northridge earthquake and build a Bayesian Generalized Additive Model of the binomial family, featuring common morphometric and thematic covariates as well as the Peak Ground Acceleration generated by the Northridge earthquake. Once each model component has been estimated, we have run 1000 simulations for each of the 217 possible ground motion scenarios for the study area. From each batch of 1000 simulations, we have estimated the mean and 95% Credible Interval to represent the mean susceptibility pattern under a specific earthquake scenario, together with its uncertainty level. Because each earthquake scenario has a specific return time, our simulations allow to incorporate the temporal dimension into any susceptibility model, therefore driving the results toward the definition of landslide hazard. Ultimately, we also share our results in vector format – a .mif file that can be easily converted into a common shapefile –. There, we report the mean (and uncertainty) susceptibility of each 1000 simulation batch for each of the 217 scenarios.

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