Predominant seismic source distance and magnitude maps for Los Angeles, Orange, and Ventura Counties, California

1996 ◽  
Vol 86 (5) ◽  
pp. 1645-1649 ◽  
Author(s):  
Chris H. Cramer ◽  
Mark D. Petersen
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
Grid Point ◽  
Seismic Source ◽  
Hazard Map ◽  
San Andreas ◽  
Source Distance ◽  
Seismic Hazard Map ◽  
First Time ◽  
Large Earthquakes

Abstract Hazard deaggregation at each grid point of a probabilistic seismic hazard map can provide maps of the most probable seismic source distance and magnitude. Maps of predominant seismic source distance and magnitude for PGA, and 5% damped spectral acceleration (SA) at 0.3-, 1.0-, and 2.0-sec periods are produced for the first time for Los Angeles, Orange, and Ventura counties in southern California. These maps show that large earthquakes on faults local to any site generally dominate the 10% probability of exceedence in 50- and 100-yr hazards in southern California. Major faults, like the San Andreas, San Jacinto, and Elsinore faults, dominate mainly in their vicinity. At spectral periods beyond 2 sec, earthquakes on these major faults can dominate out to larger distances.

scholarly journals A revised position for the primary strand of the Pleistocene-Holocene San Andreas fault in southern California

2021 ◽  
Vol 7 (13) ◽  
pp. eaaz5691
Author(s):  
Kimberly Blisniuk ◽  
Katherine Scharer ◽  
Warren D. Sharp ◽  
Roland Burgmann ◽  
Colin Amos ◽  
...  
Keyword(s):  
Los Angeles ◽  
Southern California ◽  
San Andreas Fault ◽  
Slip Rate ◽  
Large Magnitude ◽  
Slip Rates ◽  
San Andreas ◽  
The Pacific ◽  
Large Earthquakes ◽  
Dependent Probability

The San Andreas fault has the highest calculated time-dependent probability for large-magnitude earthquakes in southern California. However, where the fault is multistranded east of the Los Angeles metropolitan area, it has been uncertain which strand has the fastest slip rate and, therefore, which has the highest probability of a destructive earthquake. Reconstruction of offset Pleistocene-Holocene landforms dated using the uranium-thorium soil carbonate and beryllium-10 surface exposure techniques indicates slip rates of 24.1 ± 3 millimeter per year for the San Andreas fault, with 21.6 ± 2 and 2.5 ± 1 millimeters per year for the Mission Creek and Banning strands, respectively. These data establish the Mission Creek strand as the primary fault bounding the Pacific and North American plates at this latitude and imply that 6 to 9 meters of elastic strain has accumulated along the fault since the most recent surface-rupturing earthquake, highlighting the potential for large earthquakes along this strand.

Fleeing the Soviet Union, Dancing on the West Coast

Experiment ◽  
2014 ◽  
Vol 20 (1) ◽  
pp. 297-316
Author(s):  
Lorin Johnson ◽  
Donald Bradburn
Keyword(s):  
Soviet Union ◽  
Los Angeles ◽  
High Power ◽  
West Coast ◽  
Southern California ◽  
The West ◽  
The Arts ◽  
The Soviet Union ◽  
First Time

In the 1970s and 1980s, Los Angeles audiences saw Soviet defectors Mikhail Baryshnikov, Alexander Godunov, Natalia Makarova, and Rudolf Nureyev in the prime of their careers at the Hollywood Bowl, The Dorothy Chandler Pavilion and the Greek Theater. Dance photographer Donald Dale Bradburn, a local Southern California dancer describes his behind-the-scenes access to these dancers in this interview. Perfectly positioned as Dance Magazine’s Southern California correspondent, Bradburn offers a candid appraisal of the Southern California appeal for such high-power Russian artists as well as their impact on the arts of Los Angeles. An intimate view of Russian dancers practicing their craft on Los Angeles stages, Bradburn’s interview is illustrated by fourteen of his photographs, published for the first time in this issue of Experiment.

scholarly journals Dynamic models of earthquake rupture along branch faults of the eastern San Gorgonio Pass region in California using complex fault structure

Geosphere ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 474-489 ◽  
Author(s):  
Roby Douilly ◽  
David D. Oglesby ◽  
Michele L. Cooke ◽  
Jennifer L. Hatch
Keyword(s):  
Finite Element ◽  
Los Angeles ◽  
Southern California ◽  
San Andreas Fault ◽  
Recurrence Time ◽  
Fault Geometry ◽  
Regional Stress ◽  
Coachella Valley ◽  
San Andreas ◽  
Valley Segment

Abstract Geologic data suggest that the Coachella Valley segment of the southern San Andreas fault (southern California, USA) is past its average recurrence time period. At its northern edge, this right-lateral fault segment branches into the Mission Creek and Banning strands of the San Andreas fault. Depending on how rupture propagates through this region, there is the possibility of a throughgoing rupture that could lead to the channeling of damaging seismic energy into the Los Angeles Basin. The fault structures and potential rupture scenarios on these two strands differ significantly, which highlights the need to determine which strand provides a more likely rupture path and the circumstances that control this rupture path. In this study, we examine the effect of different assumptions about fault geometry and initial stress pattern on the dynamic rupture process to test multiple rupture scenarios and thus investigate the most likely path(s) of a rupture that starts on the Coachella Valley segment. We consider three types of fault geometry based on the Southern California Earthquake Center Community Fault Model, and we create a three-dimensional finite-element mesh for each of them. These three meshes are then incorporated into the finite-element method code FaultMod to compute a physical model for the rupture dynamics. We use a slip-weakening friction law, and consider different assumptions of background stress, such as constant tractions and regional stress regimes with different orientations. Both the constant and regional stress distributions show that rupture from the Coachella Valley segment is more likely to branch to the Mission Creek than to the Banning fault strand. The fault connectivity at this branch system seems to have a significant impact on the likelihood of a throughgoing rupture, with potentially significant impacts for ground motion and seismic hazard both locally and in the greater Los Angeles metropolitan area.

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.

scholarly journals Seismic hazard assessment in the Ibero-Maghreb region

1999 ◽  
Vol 42 (6) ◽  
Author(s):  
M. J. Jiménez ◽  
M. García-Fernández
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Earthquake Hazard ◽  
Seismic Source ◽  
Common Procedure ◽  
Fruitful Cooperation ◽  
Seismic Hazard Map ◽  
First Time ◽  
Regional Earthquake

The contribution of the Ibero-Maghreb region to the global GSHAP map has been the result of a fruitful cooperation among the participants in the established Working Group including representatives from Algeria, Morocco, Portugal, Spain and Tunisia and coordinated by ICTJA-CSIC, Spain. For the first time, a map of regional seismic source zones is presented, and agreement on a common procedure for hazard computation in the region has been achieved. The computed Ibero-Maghreb seismic hazard map constitutes the first step towards a uniform hazard assessment for the region. Further joint regional efforts are still needed for earthquake hazard studies based on a homogeneous regional earthquake catalogue. Ongoing initiatives in relation to seismic hazard assessment in the Mediterranean should profit both from these results and the established cooperation among different groups in the region as well as contribute to future regional studies.

scholarly journals Probabilistic seismic hazard map for Romania as a basis for a new building code

2005 ◽  
Vol 5 (5) ◽  
pp. 679-684 ◽  
Author(s):  
L. Ardeleanu ◽  
G. Leydecker ◽  
K.-P. Bonjer ◽  
H. Busche ◽  
D. Kaiser ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Grid Point ◽  
Building Code ◽  
Probabilistic Seismic Hazard Assessment ◽  
Eurocode 8 ◽  
Probabilistic Seismic Hazard ◽  
Hazard Map ◽  
Intermediate Depth ◽  
Attenuation Law ◽  
Seismic Hazard Map

Abstract. A seismic hazard map proposed as part of a new building code for Romania is presented here on basis of the recommendations in EUROCODE 8. Seismic source zones within an area of about 200 km around Romania were constructed considering seismicity, neotectonics and geological development. The probabilistic seismic hazard assessment in terms of intensities is performed following Cornell (1968) with the program EQRISK (see Mc Guire, 1976), modified by us for use of intensities. To cope with the irregular isoseismals of the Vrancea intermediate depth earthquakes a factor Ω is introduced to the attenuation law (Kövesligethy, 1907). Using detailed macroseismic maps of three earthquakes Ω is calculated by fitting the attenuation law to observed intensities, i.e. to local ground conditions. Strong local variation of Ω is avoided by a gridding of 0.5° in longitude and 0.25° in latitude. The contribution of the Vrancea intermediate depth zone to the seismic hazard at each grid point is computed with the corresponding representative Ω. A seismogenic depth of 120 km is assumed. The final seismic hazard is the combination of both contributions, of zones with crustal earthquakes and of the Vrancea intermediate depth earthquakes zone. Calculations are done for a recurrence period of 95, 475 and 10000 years. All maps show the dominating effects of the intermediate depth earthquakes in the Vrancea zone, also for the capital Bucharest.  

scholarly journals Contributed Reports of Widely Felt Earthquakes in California, United States: If They Felt it, Did They Report it?

2021 ◽  
Vol 9 ◽  
Author(s):  
Susan E. Hough
Keyword(s):  
Los Angeles ◽  
Household Income ◽  
Southern California ◽  
Response Rate ◽  
Clear Correlation ◽  
Intensity Data ◽  
First Order ◽  
Average Household Income ◽  
Large Earthquakes ◽  
Zip Code

In a recent study, Hough and Martin (2021) considered the extent to which socioeconomic factors influence the numbers and distribution of contributed reports available to characterize the effects of both historical and recent large earthquakes. In this study I explore the question further, focusing on analysis of widely felt earthquakes near major population centers in northern and southern California since 2002. For most of these earthquakes there is a correlation between average household income in a postal ZIP code and the population-normalized rate of responses to the DYFI system. As past studies have demonstrated, there is also a strong correlation between DYFI participation and the severity of shaking. This first-order correlation can obscure correlations with other factors that influence participation. Focusing on five earthquakes between 2011 and 2021 that generated especially uniform shaking across the greater Los Angeles, California, region, response rate varies by two orders of magnitude across the region, with a clear correlation with demographics, and consistent spatial patterns in response rate for earthquakes 10 years apart. While there is no evidence that uneven DYFI participation in California impacts significantly the reliability of intensity data collected, the results reveal that DYFI participation is significantly higher in affluent parts of southern California compared to economically disadvantaged areas.

scholarly journals Detection and Establishment of Aedes notoscriptus (Diptera: Culicidae) Mosquitoes in Southern California, United States

2021 ◽  
Author(s):  
Marco E Metzger ◽  
J Wakoli Wekesa ◽  
Susanne Kluh ◽  
Kenn K Fujioka ◽  
Robert Saviskas ◽  
...  
Keyword(s):  
Los Angeles ◽  
Urban Areas ◽  
Southern California ◽  
Close Association ◽  
Pacific Region ◽  
Rapid Spread ◽  
Global Movement ◽  
First Time ◽  
Water Holding ◽  
Artificial Water

Abstract Aedes notoscriptus (Skuse), the Australian backyard mosquito, is a pestiferous daytime-biting species native to Australia and the surrounding southwestern Pacific region. It is suspected to play a role in the transmission of several arboviruses and is considered a competent vector of dog heartworm, Dirofilaria immitis (Leidy). This highly adaptable mosquito thrives in natural and artificial water-holding containers in both forested and urbanized areas, from tropical to temperate climates, and has benefitted from a close association with humans, increasing in abundance within its native range. It invaded and successfully established in New Zealand as well as in previously unoccupied temperate and arid regions of Australia. Ae. notoscriptus was discovered in Los Angeles County, CA, in 2014, marking the first time this species had been found outside the southwestern Pacific region. By the end of 2019, immature and adult mosquitoes had been collected from 364 unique locations within 44 cities spanning three southern California counties. The discovery, establishment, and rapid spread of this species in urban areas may signal the global movement and advent of a new invasive container-inhabiting species. The biting nuisance, public health, and veterinary health implications associated with the invasion of southern California by this mosquito are discussed.

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