Erratum

In the Briefing "Tyler Prize goes to Cornell scientists" (News & Comment, 30 Mar., p. 1539), it is incorrectly stated that the Tyler committee is based at the University of California at Los Angeles. The committee has been based for the past 10 years at the University of Southern California in Los Angeles.     

Evidence for large earthquakes in metropolitan los angeles

The Sierra Madre fault, along the southern flank of the San Gabriel Mountains in the Los Angeles region, has failed in magnitude 7.2 to 7.6 events at least twice in the past 15,000 years. Restoration of slip on the fault indicated a minimum of about 4.0 meters of slip from the most recent earthquake and suggests a total cumulative slip of about 10.5 meters for the past two prehistoric earthquakes. Large surface displacements and strong ground motions resulting from greater than magnitude 7 earthquakes within the Los Angeles region are not yet considered in most seismic hazard and risk assessments.     

Recognition of paleoearthquakes on the Puente Hills blind thrust fault,California

Borehole data from young sediments folded above the Puente Hills blind thrust fault beneath Los Angeles reveal that the folding extends to the surface as a discrete zone (相似文献   

Establishment of the Mediterranean fruit fly in California

Principles of invasion biology are brought to bear on the question of whether the medfly is established in California. Since its first discovery in 1975, the pest has been captured in the Los Angeles Basin in nine separate years including every year from 1986 through 1990. The trend has become distinct--the intervals between captures are decreasing, the numbers captured are increasing, and the area over which they are detected is expanding. In addition, appearances are seasonal and captures in recent years have occurred in many of the same cities and neighborhoods where medflies were found several years before. Evidence suggests that the medfly may be established in the Los Angeles area and that previous eradication programs did not eradicate the medfly from California. It follows that detection, exclusion, and eradication protocols may need to be reexamined.     

The magnitude 6.7 northridge, california, earthquake of 17 january 1994

The most costly American earthquake since 1906 struck Los Angeles on 17 January 1994. The magnitude 6.7 Northridge earthquake resulted from more than 3 meters of reverse slip on a 15-kilometer-long south-dipping thrust fault that raised the Santa Susana mountains by as much as 70 centimeters. The fault appears to be truncated by the fault that broke in the 1971 San Fernando earthquake at a depth of 8 kilometers. Of these two events, the Northridge earthquake caused many times more damage, primarily because its causative fault is directly under the city. Many types of structures were damaged, but the fracture of welds in steel-frame buildings was the greatest surprise. The Northridge earthquake emphasizes the hazard posed to Los Angeles by concealed thrust faults and the potential for strong ground shaking in moderate earthquakes.     

The 1987 whittier narrows earthquake in the los angeles metropolitan area, california

The Whittier Narrows earthquake sequence (local magnitude, M(L) = 5.9), which caused over $358-million damage, indicates that assessments of earthquake hazards in the Los Angeles metropolitan area may be underestimated. The sequence ruptured a previously unidentified thrust fault that may be part of a large system of thrust faults that extends across the entire east-west length of the northern margin of the Los Angeles basin. Peak horizontal accelerations from the main shock, which were measured at ground level and in structures, were as high as 0.6g (where g is the acceleration of gravity at sea level) within 50 kilometers of the epicenter. The distribution of the modified Mercalli intensity VII reflects a broad north-south elongated zone of damage that is approximately centered on the main shock epicenter.     

Industrial air pollution: possible effect on lung cancer

Higher lung cancer mortality rates occurred in males living in certain heavily industrialized areas of Los Angeles County, California. These areas were characterized by elevated concentrations of benzo[a]pyrene and other polynuclear aromatic hydrocarbons of primarily industrial origin in the soil and air.     

Point mugu, california, earthquake of 21 february 1973 and its aftershocks

Seismological investigations show that the Point Mugu earthquake involved north-south crustal shortening deep within the complex fault zone that marks the southern front of the Transverse Ranges province. This earthquake sequence results from the same stress system responsible for the deformation in this province in the Pliocene through Holocene and draws attention to the significant earthquake hazard that the southern frontal fault system poses to the Los Angeles metropolitan area.     

Satellite photograph presents first comprehensive view of local wind: the santa ana

The photograph of the 1 January 1973 Santa Ana wind condition reveals local atmospheric dynamics rarely recorded on satellite imagery. The Santa Ana wind implies very specific weather conditions for the Los Angeles coastal lowland. Destructive land uses, in part, provided the material visible in the dust plumes.     

Erratum

The address given for Small Talk/V, Digitalk, Inc., in reference 2 of the software review "PC sofotware for artificial intelligence applications" by Helmut Epp et al. (6 May, p. 824) was incorrect. It should have been 9841 Airport Boulevard, Los Angeles, CA 90045.     

Erratum

In Eliot Marshall's article "Reinventing the space truck" (News & Comment, 16 Oct., p. 266), the photo identification was reversed. The Martin Marietta rocket design was on the right, and the Hughes Aircraft design was on the left. Also, the Air Force's Space Division is in Los Angeles, not Denver.     

DDT residues: distribution of concentrations in Emerita analoga (stimpson) along coastal California

The total concentrations (tDDT) of DDT [1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane], DDD [1,1-dichloro-2,2-bis(p-chlorophenyl)ethanel, and DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene] in Emerita analoga from 19 California beaches reflect tDDT contamination nearby. Animals near the Los Angeles County sewer outfall contain over 45 times as much tDDT as animals near major agricultural drainage areas. Sediments near the outfall probably contain over 100 metric tons of tDDT-a reservoir for input into marine organisms. The effluent from a plant that manufactures DDT is a probable source.     

Chemical composition of Acid fog

Fog water collected at three sites in Los Angeles and Bakersfield, California, was found to have higher acidity and higher concentrations of sulfate, nitrate, and ammonium than previously observed in atmospheric water droplets. The pH of the fog water was in the range of 2.2 to 4.0. The dominant processes controlling the fog water chemistry appear to be the condensation and evaporation of water vapor on preexisting aerosol and the scavenging of gas-phase nitric acid.     

Northridge earthquake damage caused by geologic focusing of seismic waves

Despite being located 21 kilometers from the epicenter of the 1994 Northridge earthquake (magnitude 6.7), the city of Santa Monica experienced anomalously concentrated damage with Mercalli intensity IX, an intensity as large as that experienced in the vicinity of the epicenter. Seismic records from aftershocks suggest that the damage resulted from the focusing of seismic waves by several underground acoustic lenses at depths of about 3 kilometers, formed by the faults that bound the northwestern edge of the Los Angeles basin. The amplification was greatest for high-frequency waves and was less powerful at lower frequencies, which is consistent with focusing theory and finite-difference simulations.     

Erratum

In the article "Women scientists and engineers: Trends in participation," by, Betty M. Vetter (18 Dec., p. 1313), a study by C. Rose was incorrectly cited in reference 12. The correct citation is C. Rose, Academic Employment and Graduate Enrollment Pattern and Trends of Women in Science and Engineering (Final Technical Report to the National Science Foundation, Evaluation and Training Institute, Los Angeles, Calif., 1978).     

Carboxyhemoglobin concentrations in blood from donors in Chicago, Milwaukee, New York, and Los Angeles

To determine the carbon monoxide exposure experienced by the residents of Chicago, Los Angeles, Milwaukee, and New York, venous blood samples were obtained from adults at arbitrarily chosen blood bank collection sites in the four cities and analyzed for circulating carbon monoxide, carboxyhemoglobin. For comparative purposes, blood was obtained from volunteers breathing carbon monoxide-free air and was found to contain 0.45 percent carboxyhemoglobin. By contrast a high percentage of all the nonsmoking blood donors breathing city air had carboxyhemoglobin saturations greater than 1.5 percent, which indicated that exposure to carbon monoxide in excess of that permitted by the quality standards of the Clean Air Act of 1971 was widespread and occurring regularly.     

Controlling urban air pollution: a benefit-cost assessment

To help focus debate about the best use of society's resources, it is important to have estimates of the benefits and costs of further improvements in air quality. Such estimates are developed, with focus primarily on reductions in ground-level ozone resulting from the control of volatile organic compounds; to a lesser extent, particulate control also is considered. Proposed controls are evaluated for both the nation as a whole and for the Los Angeles metropolitan area, where violations of air quality standards are most frequent and severe. Subject to a number of uncertainties, the costs of proposed new controls are found to exceed the benefits, perhaps by a considerable margin.     

Erratum

In the article " ;Nuclear winter' from Gulf war discounted," by Eliot Marshall (News & Comment, 25 Jan., p. 372), Tica Novakov's affiliation should have been given as the Lawrence Berkeley Laboratory, not the Lawrence Livermore National Laboratory. The concentrations of airborne soot reported at various locations should have been given as follows: for greater Los Angeles (summer), a daily average of 5 micrograms per cubic meter; Beijing (winter), a monthly average of 50 micrograms per cubic meter; Yugoslavia (winter), a daily average of 60 micrograms; and London (1-day winter peak in 1952), 750 micrograms, now reduced to less than 15 micrograms.     

Prospects for larger or more frequent earthquakes in the los angeles metropolitan region

Far too few moderate earthquakes have occurred within the Los Angeles, California, metropolitan region during the 200-year-long historic period to account for observed strain accumulation, indicating that the historic era represents either a lull between clusters of moderate earthquakes or part of a centuries-long interseismic period between much larger (moment magnitude, M(w), 7.2 to 7.6) events. Geologic slip rates and relations between moment magnitude, average coseismic slip, and rupture area show that either of these hypotheses is possible, but that the latter is the more plausible of the two. The average time between M(w) 7.2 to 7.6 earthquakes from a combination of six fault systems within the metropolitan area was estimated to be about 140 years.     

Rates of late cenozoic uplift, baldwin hills, los angeles, california

Radiocarbon ages for the marine late Pleistocene stratigraphic units of the Baldwin Hills are 36,200 +/- 2,750 years and 28,450 +/- 2,600 years, respectively, defining the termination of marine deposition in this area of the Los Angeles Basin at less than 28,000 years ago. Faunas of the older sample suggest that water depths were about 100 meters at the time of deposition. Shoaling of waters by deposition resulted in very shallow marine to nonmarine conditions about 28,000 years ago. The average rates of uplift for the past 36,000 years have been between 0.5 and 0.8 meter per 100 years.