scholarly journals Work in progress: relative safety of high-rise and low-rise buildings in Los Angeles

2008 ◽  
Vol 17 (6) ◽  
pp. 1025-1029 ◽  
Author(s):  
Farzin Zareian
Keyword(s):  
Los Angeles ◽  
Work In Progress ◽  
High Rise ◽  
Relative Safety

2019 Ridgecrest Earthquake Reveals Areas of Los Angeles That Amplify Shaking of High-Rises

2020 ◽  
Vol 91 (6) ◽  
pp. 3370-3380
Author(s):  
Monica D. Kohler ◽  
Filippos Filippitzis ◽  
Thomas Heaton ◽  
Robert W. Clayton ◽  
Richard Guy ◽  
...  
Keyword(s):  
Los Angeles ◽  
Strong Motion ◽  
Ground Level ◽  
Site Amplification ◽  
Seismic Network ◽  
Los Angeles Basin ◽  
High Rise ◽  
The North ◽  
South Central ◽  
San Fernando

Abstract The populace of Los Angeles, California, was startled by shaking from the M 7.1 earthquake that struck the city of Ridgecrest located 200 km to the north on 6 July 2019. Although the earthquake did not cause damage in Los Angeles, the experience in high-rise buildings was frightening in contrast to the shaking felt in short buildings. Observations from 560 ground-level accelerometers reveal large variations in shaking in the Los Angeles basin that occurred for more than 2 min. The observations come from the spatially dense Community Seismic Network (CSN), combined with the sparser Southern California Seismic Network and California Strong Motion Instrumentation Program networks. Site amplification factors for periods of 1, 3, 6, and 8 s are computed as the ratio of each station’s response spectral values combined for the two horizontal directions, relative to the average of three bedrock sites. Spatially coherent behavior in site amplification emerges for periods ≥3  s, and the maximum calculated site amplifications are the largest, by factors of 7, 10, and 8, respectively, for 3, 6, and 8 s periods. The dense CSN observations show that the long-period amplification is clearly, but only partially, correlated with the depth to basement. Sites with the largest amplifications for the long periods (≥3  s) are not close to the deepest portion of the basin. At 6 and 8 s periods, the maximum amplifications occur in the western part of the Los Angeles basin and in the south-central San Fernando Valley sedimentary basin. The observations suggest that the excitation of a hypothetical high-rise located in an area characterized by the largest site amplifications could be four times larger than in a downtown Los Angeles location.

scholarly journals Downtown Los Angeles 52-Story High-Rise and Free-Field Response to an Oil Refinery Explosion

2016 ◽  
Vol 32 (3) ◽  
pp. 1793-1820 ◽  
Author(s):  
Monica D. Kohler ◽  
Anthony Massari ◽  
Thomas H. Heaton ◽  
Hiroo Kanamori ◽  
Egill Hauksson ◽  
...  
Keyword(s):  
Los Angeles ◽  
Pressure Wave ◽  
Free Field ◽  
Seismic Network ◽  
Oil Refinery ◽  
Elastic Response ◽  
Force System ◽  
Ground Shaking ◽  
High Rise ◽  
Downtown Los Angeles

The ExxonMobil Corp. oil refinery in Torrance, California, experienced an explosion on 18 February 2015, causing ground shaking equivalent to a magnitude 2.0 earthquake. The impulse response for the source was computed from Southern California Seismic Network data for a single force system with a value of 2 × 105 kN vertically downward. The refinery explosion produced an air pressure wave that was recorded 22.8 km away in a 52-story high-rise building in downtown Los Angeles by a dense accelerometer array that is a component of the Community Seismic Network. The array recorded anomalous waveforms on each floor displaying coherent arrivals that are consistent with the building's elastic response to a pressure wave caused by the refinery explosion. Using a finite-element model of the building, the force on the building on a floor-by-floor scale was found to range up to 1.42 kN, corresponding to a pressure perturbation of 7.7 Pa.

Cities, People, Planet

2004 ◽  
Author(s):  
Herbert Girardet
Keyword(s):  
Hong Kong ◽  
Los Angeles ◽  
Urban Areas ◽  
High Rise ◽  
Modern Cities ◽  
Physical Scale ◽  
The Usa ◽  
Primary Habitat ◽  
City Centres ◽  
Mega Cities

As urban areas become our primary habitat—three-quarters of the human population are expected to become city dwellers by around 2050 (Worldwatch Institute 2000)—it is of key importance to establish whether a sustainable relationship can be established between cities and the planet. The urgency of this task is only too evident: the size of modern cities in terms of numbers of citizens and physical scale is unprecedented: in 1800 there was only one city of a million people: London. At that time the largest 100 cities in the world had 20 million inhabitants, with each city usually extending to just a few thousand hectares. In 1990 the world’s 100 largest cities accommodated 540 million people, of which 220 million people lived in the 20 largest cities, mega-cities of over 10 million people, some extending to hundreds of thousands of hectares. In addition, there were 35 cities of over 5 million and hundreds of over one million people (Satterthwaite 1996). Urban sprawl is a major concern for environmentalists. It is typical of cities of increasing affluence in which people often prefer the spaciousness of suburbs to denser city centres. Metropolitan New York’s population, for instance, has grown only 5 per cent in the last 25 years, yet its surface area has grown by 61 per cent, consuming much forest and farmland in the process. In the USA and Europe, sprawl today is above all else caused by the routine use of the motor car. Los Angeles is famous for the way it sprawls along its vastly complex freeway system. Ninety per cent of its population drive to work by car and many live in detached houses surrounded by large patches of land. A city of 11 million people, it covers an area three times larger than London which has a population of 7 million. London itself, where semi-detached houses are the norm in the suburbs, is several times larger than Hong Kong which has 6 million inhabitants and where most people live in high rise blocks. Not surprisingly, Hong Kong uses space far more efficiently than either LA or London.

scholarly journals Security and Safety in Los Angeles High Rise Buildings After 9/11

10.7249/db381 ◽  
2002 ◽  
Author(s):  
Rae Archibald ◽  
Jamison Medby ◽  
Brian Rosen ◽  
Jonathan Schachter
Keyword(s):  
Los Angeles ◽  
High Rise

scholarly journals Parsimonious velocity inversion applied to the Los Angeles Basin, CA

2021 ◽  
Author(s):  
Jack Muir ◽  
Robert Clayton ◽  
Victor Tsai ◽  
Quentin Brissaud
Keyword(s):  
Los Angeles ◽  
Wave Dispersion ◽  
Regional Models ◽  
Los Angeles Basin ◽  
Local Data ◽  
Velocity Inversion ◽  
High Rise ◽  
Velocity Models ◽  
Derivative Free ◽  
Approximate Bayesian

The proliferation of dense arrays promises to improve our ability to image geological structures at the scales necessary for accurate assessment of seismic hazard. However, combining the resulting local high-resolution tomography with existing regional models presents an ongoing challenge. We developed a framework based on the level-set method that provides a means to infer where local data provides meaningful constraints beyond those found in regional models - e.g. the Community Velocity Models (CVMs) of southern California. This technique defines a volume within which updates are made to a reference CVM, with the boundary of the volume being part of the inversion rather than explicitly defined. By penalizing the complexity of the boundary, a minimal update that sufficiently explains the data is achieved. To test this framework, we use data from the Community Seismic Network, a dense permanent urban deployment. We inverted Love wave dispersion and amplification data, from the Mw 6.4 and 7.1 2019 Ridgecrest earthquakes. We invert for an update to CVM-S4.26 using the Tikhonov Ensemble Sampling scheme, a highly efficient derivative-free approximate Bayesian method. We find the data is best explained by a deepening of the Los Angeles Basin with its deepest part south of downtown Los Angeles, along with a steeper northeastern basin wall. This result offers new progress towards the parsimonious incorporation of detailed local basin models within regional reference models utilizing an objective framework and highlights the importance of accurate basin models when accounting for the amplification of surface waves in the high-rise building response band.

In His Element

2017 ◽  
Author(s):  
James Naremore
Keyword(s):  
Los Angeles ◽  
Hurricane Katrina ◽  
Black Family ◽  
Experimental Mixture ◽  
Work In Progress ◽  
Short Films ◽  
Mother And Daughter

Some of Burnett’s most characteristic and impressive work has taken the form of completely independent, very low budget short films that he has written, directed, photographed, and edited. These films return him to his beginnings as a sort of guerilla filmmaker who works in the streets. This chapter gives three examples: When It Rains (1995), a jazz fable about a neighborhood griot who tries to keep a mother and daughter from being evicted; The Final Insult (1997), an experimental mixture of documentary and fiction concerning homelessness in Los Angeles; and Quiet As Kept, a darkly comic film about a black family that has been displaced by Hurricane Katrina. The chapter ends with a comment on Burnett’s work in progress and his continuing importance for us today.

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

Sinusoidal Cells in Bone Marrow Take Up BSA-Au Conjugates in the Presence of an Artificial Blood Substitute

1985 ◽  
Vol 43 ◽  
pp. 700-701
Author(s):  
J.S. Geoffroy ◽  
R.P. Becker
Keyword(s):  
Bone Marrow ◽  
Los Angeles ◽  
Iliac Artery ◽  
Blood Substitute ◽  
Sprague Dawley ◽  
Coated Pits ◽  
Sinusoidal Cells ◽  
Artificial Blood ◽  
Left Common Iliac Artery

The pattern of BSA-Au uptake in vivo by endothelial cells of the venous sinuses (sinusoidal cells) of rat bone marrow has been described previously. BSA-Au conjugates are taken up exclusively in coated pits and vesicles, enter and pass through an “endosomal” compartment comprised of smooth-membraned tubules and vacuoles and cup-like bodies, and subsequently reside in multivesicular and dense bodies. The process is very rapid, with BSA-Au reaching secondary lysosmes one minute after presentation. (Figure 1)In further investigations of this process an isolated limb perfusion method using an artificial blood substitute, Oxypherol-ET (O-ET; Alpha Therapeutics, Los Angeles, CA) was developed. Under nembutal anesthesia, male Sprague-Dawley rats were laparotomized. The left common iliac artery and vein were ligated and the right iliac artery was cannulated via the aorta with a small vein catheter. Pump tubing, preprimed with oxygenated 0-ET at 37°C, was connected to the cannula.

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