Geophysical Setting of the San Fernando Basin, Southern California

2001 ◽  
Author(s):  
V.E. Langenheim ◽  
T.G. Hildenbrand ◽  
R.C. Jachens ◽  
A. Griscom
Keyword(s):  
Southern California ◽  
San Fernando

Damping Values Derived from Surface-Source, Downhole-Receiver Measurements at 22 Sites in the San Francisco Bay Area of Central California and the San Fernando Valley of Southern California

2020 ◽  
Author(s):  
David M. Boore ◽  
James F. Gibbs ◽  
William B. Joyner
Keyword(s):  
San Francisco ◽  
Southern California ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Damping Ratio ◽  
Surface Source ◽  
Central California ◽  
Bay Area ◽  
San Fernando ◽  
San Fernando Valley

Abstract A method discussed in Gibbs, Boore, et al. (1994) was applied to surface-source, downhole-receiver recordings at 22 boreholes, in the San Francisco Bay area in central California and the San Fernando Valley of southern California, to determine the average damping ratio of shear waves over depth intervals ranging from about 10 m to as much as 245 m (at one site), with most maximum depths being between 35 and 90 m. The average damping values range from somewhat less than 1% to almost 8%, with little dependence on grain size for sites in sediments. Surprisingly, the average damping values for sites with average velocities greater than about 450  m/s, including, but not limited to rock sites, are generally larger than for sites with lower average velocities. The combined effect of the higher damping and shorter travel times through the rock columns, however, leads to an effective attenuation that is generally comparable or smaller than for soil sites.

scholarly journals Performance of Two 18-Story Steel Moment-Frame Buildings in Southern California during Two Large Simulated San Andreas Earthquakes

2006 ◽  
Vol 22 (4) ◽  
pp. 1035-1061 ◽  
Author(s):  
Swaminathan Krishnan ◽  
Chen Ji ◽  
Dimitri Komatitsch ◽  
Jeroen Tromp
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
Building Code ◽  
Los Angeles Basin ◽  
Moment Frame ◽  
Steel Moment Frame ◽  
Existing Building ◽  
San Andreas ◽  
Frame Buildings ◽  
San Fernando

Using state-of-the-art computational tools in seismology and structural engineering, validated using data from the Mw=6.7 January 1994 Northridge earthquake, we determine the damage to two 18-story steel moment-frame buildings, one existing and one new, located in southern California due to ground motions from two hypothetical magnitude 7.9 earthquakes on the San Andreas Fault. The new building has the same configuration as the existing building but has been redesigned to current building code standards. Two cases are considered: rupture initiating at Parkfield and propagating from north to south, and rupture propagating from south to north and terminating at Parkfield. Severe damage occurs in these buildings at many locations in the region in the north-to-south rupture scenario. Peak velocities of 1 m.s−1 and 2 m.s−1 occur in the Los Angeles Basin and San Fernando Valley, respectively, while the corresponding peak displacements are about 1 m and 2 m, respectively. Peak interstory drifts in the two buildings exceed 0.10 and 0.06 in many areas of the San Fernando Valley and the Los Angeles Basin, respectively. The redesigned building performs significantly better than the existing building; however, its improved design based on the 1997 Uniform Building Code is still not adequate to prevent serious damage. The results from the south-to-north scenario are not as alarming, although damage is serious enough to cause significant business interruption and compromise life safety.

The Whittier Narrows, California Earthquake of October 1, 1987—Emergency Response

1988 ◽  
Vol 4 (1) ◽  
pp. 25-30 ◽  
Author(s):  
R. Andrews
Keyword(s):  
Los Angeles ◽  
Private Sector ◽  
Emergency Response ◽  
Southern California ◽  
Seismic Event ◽  
Local State ◽  
Metropolitan Region ◽  
San Fernando ◽  
Made In

The Whittier Narrows earthquake of October 1, 1987 was the most significant seismic event to occur in southern California since the San Fernando earthquake of February 1971. As such, the 5.9 magnitude temblor provided a basis for evaluating the level of preparedness in at least a portion of the Los Angeles metropolitan region. The Whittier Narrows event provides a hint of the progress that has been made in local, state and private sector preparedness in the last six years as well as suggesting areas that need additional effort.

scholarly journals Preliminary potential-field constraints on the geometry of the San Fernando basin, Southern California

2000 ◽  
Author(s):  
Victoria E. Langenheim ◽  
Andrew Griscom ◽  
R.C. Jachens ◽  
T.G. Hildenbrand
Keyword(s):  
Potential Field ◽  
Southern California ◽  
San Fernando

scholarly journals Palmdale Bulge and its significance

1978 ◽  
Vol 11 (3) ◽  
pp. 193-194
Author(s):  
G. J. Lensen
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
Los Angeles Basin ◽  
Epicentral Area ◽  
Transverse Ranges ◽  
The Future ◽  
San Fernando ◽  
Maximum Subsidence

As an aftermath to the 1971 San Fernando earthquake in southern California two existing levelling routes were relevelled in order to assess the amount of earth shift that triggered this earthquake. Comparison of
the new and old data revealed two important points: (a) the 1971 earthshift resulted in a maximum uplift of 2 m on the upthrown (Transverse Ranges) side and a maximum subsidence of 110 mm on the downthrown (Los Angeles basin complex) side. (b) prior to the 1971 earthshift the area was deforming for at least 10 years, reaching over the period 1968-69 the maximum of about 80 mm uplift in the future epicentral area.

Sign in / Sign up

Export Citation Format

Share Document