Improved Seismic Monitoring - Improved Decision-Making Assessing the Value of Reduced Uncertainty (2006) / Chapter Skim
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2 The Role of Seismic Monitoring in Decision-Making
2 The Role of Seismic Monitoring in Decision-Making
Pages 42-61
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From page 42... ...
Risk perception and choice -- how individuals, groups, and organizations process information from seismic monitoring data and how this information influences their choices. Risk management -- the role of seismic monitoring as a contributor to strategies for dealing with earthquake hazards.
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From page 43... ...
RISK ASSESSMENT: THE ROLE OF MONITORING IN DEFINING RISK AND REDUCING UNCERTAINTY Assessing the risk of earthquake damage to structures requires information concerning the · type of structure and its response to strong ground motion and other seismic hazards, · location of the structure in relation to earthquake faults, · type of faulting, and · overall distribution of strong ground shaking and its local modification by specific site geology. Quantitative estimates of seismic risk are important for judging whether earthquakes represent a substantial threat at any location; they enable objective weighting of earthquake risk relative to other natural hazards and other priorities for making design and retrofit decisions (NRC, 1996)
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From page 44... ...
Information about the locations of active faults and the size and frequency of damaging earthquakes allows decision-makers to specify appropriate design features of structures, using the seismic provisions in building codes. One component of this work is the development of "earthquake design ground motion libraries," where strong motion records from a number of different earthquakes are processed in a consistent manner and made available to earthquake engineers and researchers in a web-accessible format for a variety of magnitude, distance, and fault types.1 The collection of high-quality data at close distances is critical for validating and verifying the earthquake engineering models that are used in the construction of our urban environment.
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From page 45... ...
By contributing to the seismic zonation of the Puget Sound region, especially in identifying locations that are potentially subject to large ground motion amplification or deamplification effects, seismic monitoring information enables seismologists and engineers to obtain more reliable estimates of the ground motion levels for which structures should be designed, thereby avoiding unnecessary conservatism in design. One way to capture what is known and not known about a particular risk is to construct an "exceedance probability" (EP)
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From page 46... ...
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From page 47... ...
A company located in a hazard-prone area may wish to determine the likelihood that it will suffer direct dollar damage and indirect losses-such as business interruption -- that exceed different magnitudes in order to determine how much insurance to purchase. A building owner may want to examine how specific protective measures will shift the EP curve downwards, to provide an indication of the impact such investments will have on future dollar losses to its structure.
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From page 48... ...
. However, in other parts of the country where damaging earthquakes occur less frequently, the risk is less well understood with the result that appropriate mitigation strategies are less clear and emergency response activities for earthquakes are less well established.
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From page 49... ...
RISK PERCEPTION AND CHOICE Risk assessment focuses on the likelihood of certain events occurring, with damage and loss often able to be measured in monetary units. In the context of earthquake risk assessment, improved seismic monitoring has the potential to refine quantitative risk estimates.
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From page 50... ...
(1993) conducted a survey of 896 underwriters from 190 randomly chosen insurance companies to determine the premiums required to insure a factory against property damage from a severe earthquake.
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From page 51... ...
Projects designed to reduce losses from natural or other disasters, such as improved seismic monitoring, are expected to provide benefits in the form of costs avoided. This means that the cost of such natural disasters-without mitigation measures such as improved building codes -- must first be identified to establish a benchmark.
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From page 52... ...
Improved seismic monitoring may lead to better communication of the risk because there will be less uncertainty regarding the likelihood of a future earthquake. It may also be possible to issue appropriate warnings about the dangers of earthquakes in particular regions of the country, leading to the adoption of risk reduction measures.
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From page 53... ...
Building Codes. Building code regulations designed to mitigate seismic risk are desirable when property owners would otherwise not adopt costeffective mitigation measures because they either misperceive their prospective benefits and/or underestimate the probability of a disaster occurring.
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From page 54... ...
Improved seismic monitoring will potentially provide better data to private insurers, reinsurers, and/or the CEA so they can more accurately price the coverage and manage their accumulations of risk. This will reduce the likelihood of the insurer's suffering unexpectedly severe financial losses following a major earthquake event and, in turn, should increase the availability and lower the cost of coverage.
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From page 55... ...
Improved seismic monitoring is the key to improving the accuracy of these maps, and public sector agencies would be able to use them in their design of seismic regulations and standards. At the state level, an office of emergency services or a department of public safety promotes natural disaster preparedness.
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From page 56... ...
Networks of spatially distributed systems (transportation or utility systems) have a greater sensitivity to ground motions than individual (single-location)
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From page 57... ...
Whereas engineers use monitored seismic information to better understand damage caused to buildings and infrastructure by strong ground motion and to recommend retrofit options and mitigation strategies, emergency managers, planners, and insurers need to know the probability of damaging earthquakes in their communities for planning purposes. Emergency managers also need rapid information on magnitude, location, and ground shaking for effective response.
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From page 58... ...
. Improved seismic monitoring will permit the production of accurate, site-specific ShakeMaps throughout the United States that depict the post-earthquake conditions on the ground; present systems permit such accuracy only in southern California.
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From page 59... ...
. Seismic monitoring data provide the basis for communication of an increased seismic potential for a region -- information that may be presented as a long-term statement of seismic risk or
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From page 60... ...
With recent advances in technology, it is quite possible to obtain basic seismic information before the first public or news media inquiry is received. The availability of such realtime information, however, is limited to those areas with dense networks of modern digital seismic stations and instantaneous communication of
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From page 61... ...
Typically, after such an earthquake occurs, the news media converge at the network hub and scientists interpret what has happened for the assembled journalists. The close relationship that has evolved in some regions between seismic network operators and the news media has facilitated the transfer of new knowledge and technologies to news organizations.
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