The race to seismic safety : protecting California's transportation system (original) (raw)
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A new and defective regulation in California for protecting critical buildings from earthquakes
Engineering Geology, 2003
The California Geological Survey issued a new regulatory directive specifying that critical buildings be designed for 50-and 100-year earthquakes obtained by probabilistic seismic hazard analysis (PSHA). PSHA incorporates serious uncertainties. Chiefly, they are: (1) PSHA smears earthquakes together to produce motions that are unrealistic for any specific earthquakegenerating fault source, (2) PSHA assumes there is an essentially log -linear predictability through time for both the sizes of earthquakes and their motions, although earthquake experiences deny this assumption, and (3) PSHA derives design values from an almost total lack of data on the recurrences that it claims to represent. Error bands for probabilistic motions, if honestly applied, would be so enormously broad that probabilistic values would be seen to be too uncertain as a rational basis for critical designs. Worse yet, the directive of the California Geological Survey has forced a de facto elimination of deterministic seismic hazard analysis (DSHA) from consideration. Yet, DSHA provides more logical, more transparent, more peer reviewable, and more dependable solutions than does PSHA. In summary, the new regulatory directive fails to provide the public in California with a necessary level of seismic safety. D
Journal of Transportation and Statistics: Special Issue on the Northridge Earthquake
1998
Commerce was also affected by the earthquake. I-5 is the major northsouth corridor of the Pacific Rim states, and was effectively severed for several days. Traffic between the Los Angeles-San Diego area and Northern California could use U.S. 101 without too much added circuitry, but traffic to Bakersfield and the agricultural portions of the southern San Joaquin Valley was diverted via San Luis Obispo or San Bernardino with much greater relative circuitry. Twenty days after the earthquake, representatives of the Bureau of Transportation Statistics (BTS) delivered special tabulations of census data to assist local transportation planners. While delivering the data, BTS was able to observe the damage and the response of local agencies. BTS recognized that the Northridge earthquake and its aftermath provided a natural laboratory to examine travel behavior, the reliability of the transportation system, and the impact of transportation disruptions on businesses and the regional economy. With BTS support,
Seismic hazard analysis for critical infrastructures in California
Engineering Geology, 2005
California is in a highly seismically active region, and structures must be designed and constructed to withstand earthquakes. Seismic hazard analysis to estimate realistic earthquake ground motions and surface fault rupture offsets is done for various mitigation measures. The best policy is to avoid constructing structures crossing seismogenic faults. Because earthquake timings are unpredictable within our current understanding, the best method is time-invariant deterministic seismic hazard analysis (DHSA) to assess effects from the largest single earthquake called Maximum Credible Earthquake (MCEs) expected from seismogenic faults. Time-dependent hazard estimates such as those arrived at through probabilistic seismic hazard analysis (PSHA) are inherently unreliable. Hazard analyses based on MCEs have been in continuous use for the design and construction of highways and bridges in California for over 30 years.
Transportation Impacts of the 1989 Loma Prieta Earthquake: The Bay Bridge Closure
University of California Transportation Center, 1991
Based on the Berkeley Campus, UCTC draws upon existing capabiiities and resources of the Institutes of Transportation Studies at Berkeley, Davis, Irvine, and Los Angeles; the Institute of Urban and Regional Development at Berkeley; and several academic departments at the Berkeley, Davis, Irvine, and Los Angeles campuses. Faculty and students on other University of California campuses may participate in Center activities. Researchers at other universities within the region also have opportunities to collaborate with UC faculty on selected studies.
Earthquake Hazard Mitigation in the New Madrid Seismic Zone: Science and Public Policy
2016
In the central United States, earthquake sources that are not well defined, long earthquake recurrence intervals, and uncertain ground-motion attenuation models have contributed to an overstatement of seismic hazard for the New Madrid Seismic Zone on the national seismic hazard maps published by the U.S. Geological Survey. A series of informal interviews in western Kentucky with local businesspersons, public officials, and other professionals in occupations associated with seismic-hazard mitigation discussed seismic-mitigation policies in relation to depressed local economy. Scientific and relative economic analysis was then performed using scenario earthquake models developed with the Federal Emergency Management Agency's Hazus-MH software. The ground-motion hazard generated by the 2008 Wenchuan, China, earthquake and seismic mitigation policies in that area were compared with those of the New Madrid Seismic Zone. Continued scientific research, additional educational opportunities for laymen and engineering professionals, and changes in the application of current earthquake science to public policy in the central United States should help improve public safety and economic development.
Earthquakes are natural disasters that can cause an extensive amount of damage. Scientists study them to learn more about their potential to cause damage, as well as to identify any possible indicators that could signal when the quake will occur. Vulnerability is also analyzed to determine how well a population may respond and adapt to the outcome of the quake. This paper will review the impact of big earthquakes in the United States through case study examples, as well as to identify the available tools currently available to monitor the activity. Earthquakes are significant disasters in the United States. California is located along a major earthquake fault line, that is very much active. Studying the disaster response system for these earthquakes will aid in developing better safety responses and protection mechanisms. I am researching this topic to develop a better understanding of the seismic activity that can occur in California, as well as to identify safety responses for the disaster.
Seismic Hazard and Public Safety
Eos, Transactions American Geophysical Union, 2013
International Seismic Safety Organization (ISSO) has been formed to promote public safety by being prepared for the largest potential events which can happen at any time, rather than for certain probable events which have been exceeded in several recent earthquakes with disastrous consequences. The position of ISSO is available now in English, Italian, Russian, Hebrew, Spanish, and Hindi at http://www.issoquake.org. That position has been misrepresented elsewhere and this short note is to counter such inaccurate viewpoints.