Science as a Gateway to Understanding International Workshop Proceedings, Tehran, Iran (2008) / Chapter Skim
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13 Opportunities for International Collaboration in Earthquake System Science--Thomas Jordan
13 Opportunities for International Collaboration in Earthquake System Science--Thomas Jordan
Pages 101-128
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From page 101... ...
Measured as annualized economic losses, almost one-half of the total earthquake risk for the United States comes from Southern California; of that, about 25 percent comes from the Los Angeles metropolitan area alone (FEMA, 2000)
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From page 102... ...
SEISMIC RISK ANALYSIS Earthquakes proceed as cascades in which the primary effects of faulting and ground shaking induce secondary effects, such as landslides, liquefaction, and tsunamis. They set off destructive processes within the built environment, such as fires and dam failures (NRC, 2003)
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From page 103... ...
The synoptic risk studies needed for policy formulation are the responsibility of public agencies, and their accuracy and efficacy depends on technological resources not yet available in many seismically active regions. Risk assessments can be improved worldwide through international collaborations that share the expertise of earthquake scientists and engineers from countries with well-developed risk reduction programs.
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From page 104... ...
Risk estimates have been published for California's historic earthquake events, such as the 1906 San Francisco earthquake (Kircher et al., 2006) , and inferred from geologic data on the locations and magnitudes of prehistoric fault ruptures, such as the Puente Hills blind thrust system that runs beneath central Los Angeles (Field et al., 2005)
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From page 105... ...
STRATEGIES FOR SEISMIC RISK REDUCTION I will illustrate the basic strategies for reducing seismic risk using California examples. The strategies can be categorized according to the four factors in the risk equation.
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From page 106... ...
The poor performance of the emergency response to Hurricane Katrina and subsequent disaster-recovery programs, especially in the hardhit city of New Orleans, illustrate the need for better coordination 1 See peer.berkeley.edu/.
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From page 107... ...
Nevertheless, the hazard level sets the risk, and the properly characterizing seismic hazard -- forecasting earthquakes and their effects and charting earthquake cascades as they are happening -- is therefore critical to risk reduction. For instance, current hazard forecasts contain large epistemic errors that compromise the effectiveness of risk analysis when guiding political policies and economic decisions.
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From page 108... ...
. Originally developed by earthquake engineers, PSHA estimates the probability that the ground motions generated at a geographic site from all regional earthquakes will exceed some intensity measure during a time interval of interest, usually a few decades.
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From page 109... ...
.2 Southern California's network of several hundred active faults forms a superb natural laboratory for the study of earthquake physics; its seismic, geodetic, and geologic data are among the best in the world. SCEC's mission is to use this information to develop a comprehensive, physics-based understanding of the Southern California fault system, and to communicate this understanding to society as useful knowledge for reducing seismic risk.
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From page 110... ...
Geological Survey, and the California Geological Survey to produce the first comprehensive Uniform California Earthquake Rupture Forecast (WGCEP, 2007)
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From page 111... ...
Sufficient stress has reaccumulated of the southern sections of the fault to make a large rupture more likely. The UCERF model will be used by decisionmakers concerned with land-use planning, the seismic safety provisions of building codes, disaster preparation and recovery, emergency response, and earthquake insurance; engineers who need estimates of maximum seismic intensities for the design of buildings, critical facilities, and lifelines; and organizations that promote public education for mitigating earthquake risk.
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From page 112... ...
. Based on this experience, SCEC has formed an international partnership that is extending scientific earthquake prediction experiments to other fault systems through a global infrastructure for comparative testing.
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From page 113... ...
In the not-to-distant future, we will be able to incorporate much more physics into seismic hazard and risk analysis through system-level simulations. INTERNATIONAL SCIENTIFIC PARTNERSHIPS Earthquake system science relies on the premise that detailed studies of fault systems in different regions, such as Southern California, Japan, and Iran, can be synthesized into a generic understanding of earthquake phenomena.
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From page 114... ...
Systematic paleoseismic investigations have elucidated a thousandyear history of San Andreas slip (Grant and Lettis, 2002; Weldon et al., 2005) , and SCEC's current objective is to define slip rate and earthquake history of the southern San Andreas Fault system for the last 2000 years.
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From page 115... ...
Seismic data from a regional network can be processed immediately following an event and the results broadcast to users, such as emergency response agencies and responsible government officials, utility and transportation companies, and other commercial interests. The parameters include traditional estimates of origin time, hypocenter location, and magnitude, as well as Shake Maps of predicted ground motions conditioned on available strong-motion recordings, which can aid in damage assessments (Wald et al., 1999)
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From page 116... ...
In Southern California, the warning times in Los Angeles for earthquakes on the San Andreas Fault could be a minute or more, enough for individuals to prepare for shaking (e.g., by getting under a desk) and for certain types of automated decisions that might reduce damage and increase resiliency: slowing trains, stopping elevators, shutting gas lines, conditioning electrical grids, and so forth.
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From page 117... ...
SEISMIC RISK ANALYSIS From a practical point of view, the main role of earthquake system science is to promote risk reduction through better characterization of seismic hazards. For megacities like Tehran and Los Angeles, the key problem is holistic: how can we protect the societal infrastructure from extreme events that might "break the system," the way that Hurricane Katrina broke the city of New Orleans in 2005?
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From page 118... ...
Many scientists question whether such predictions will ever contribute significantly to risk reduction, even with substantial improvements in the ability to detect precursory signals; the chaotic nature of brittle deformation may simply preclude useful short-term predictions. Nevertheless, global research on earthquake predictability is resurgent, motivated by better data from seismology, geodesy, and geology; new knowledge of the physics of earthquake ruptures; and a more comprehensive understanding of how active faults systems actually work.
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From page 119... ...
As a remedy, SCEC is working with its international partners to establish a Collaboratory for the Study of Earthquake Predictability. The goals of the CSEP project are to support scientific earthquake prediction experiments in a variety of tectonic environments; promote rigorous research on earthquake predictability through comparative testing of prediction hypotheses; and help the responsible government agencies assess the feasibility of earthquake prediction and the performance of proposed prediction algorithms.
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From page 120... ...
improve earthquake forecasts by understanding fault-system evolution and the physical basis for earthquake predictability; (3) predict ground motions and their effects on the built environment by simulating earthquakes with realistic source characteristics and three-dimensional representations of geologic structures; and (4)
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From page 121... ...
1994. Natural Hazards and the First Earthquake Catalogue of Iran.
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From page 122... ...
1996. National seismic hazard mapping program, national seismic-hazard maps: documentation June 1996.
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From page 123... ...
2002. Na tional Seismic Hazard Mapping Program, Documentation for the 2002 Update of the National Seismic Hazard Maps.
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From page 124... ...
2008. TeraShake2: spontaneous rupture simulations of Mw 7.7 Earthquakes on the southern San Andreas Fault.
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From page 125... ...
2005. Past and future earthquakes on the San Andreas fault.
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From page 126... ...
2007. Uni form California Earthquake Rupture Forecast, Version 2.
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From page 127... ...
UCERF -- Uniform California Earthquake Rupture Forecast USGS -- United States Geological Survey WGCEP -- Working Group on California Earthquake Probabilities
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