Improved Seismic Monitoring - Improved Decision-Making Assessing the Value of Reduced Uncertainty (2006) / Chapter Skim
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8 Integrating the Benefits--Conclusions and Recommendations
8 Integrating the Benefits--Conclusions and Recommendations
Pages 144-158
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From page 144... ...
Annual costs for operating and maintaining the nation's existing seismic monitoring networks, including the present implementation of the federally operated network (the Advanced National Seismic System [ANSS]
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From page 145... ...
One way to proceed with this discussion of whether the anticipated economic benefits from improved seismic monitoring justify the cost to the nation is to ask how large a reduction in expected annual earthquake losses would be required to justify the investment in improved seismic monitoring. Using the FEMA estimates of annualized buildings and building-related earthquake losses of $5.6 billion, if an annual 2 percent reduction in losses resulted from mitigation measures based on improved seismic monitoring data -- a seemingly achievable result in light of the broad range of potential benefits described in this report -- then avoided losses would be greater than the maximum expected annual costs of investing in increased seismic monitoring.
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From page 146... ...
In those areas of the country with modern digital seismic networks and rapid communication of information to a central processing site where data are rapidly analyzed and disseminated, emergency managers have many useful tools at their disposal for responding to a damaging earthquake. The deployment of digital strong motion recording instruments in southern California, northern California, the Pacific Northwest, and the Salt Lake City area as part of the initial deployment of the ANSS, together with improvements in data processing and communications during the last decade, have facilitated the creation and Internet distribution of Geographic Information System (GIS)
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From page 147... ...
Nearly every recorded volcanic eruption has been preceded by an increase in earthquake activity beneath or near the volcano. For this reason, seismic monitoring has become one of the most useful tools for eruption forecasting and monitoring.
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From page 148... ...
Much of our knowledge of the location and characteristics of active faults that can generate potentially damaging ground shaking and other hazards, and the frequency of occurrence of potentially damaging earthquakes, is derived from a combination of geologic mapping and seismic monitoring. Knowledge about the source characteristics of large and small earthquakes, derived from recordings from seismic networks and other data, is used to identify and characterize the seismic potential of earthquake sources throughout the United States.
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From page 149... ...
Improved seismic monitoring will improve the accuracy of the data underpinning loss estimation models and reduce the uncertainty associated with model outputs (see Chapter 5) , leading to a number of beneficial economic impacts: · Improved model credibility will increase public knowledge, confidence, and understanding of seismic risk.
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From page 150... ...
The discussion of the benefits of performance-based engineering (Chapter 6) makes the case that improved seismic design, expected to become available as a result of improved seismic monitoring, will generate prospective annual benefits of more than $140 million.
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From page 151... ...
The current approach is based not on knowing the times and locations of future damaging earthquakes, but on assessments of their long-term frequency of occurrence. From a longer-term perspective, if we could predict or forecast damaging earthquakes that will occur in the United States over the next several years to decades, we would know where to focus mitigation activities and where such activities could be deferred.
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From page 152... ...
Until there is adequate monitoring of strong ground motion in the United States, earthquake engineering practice will continue to be subject to very great uncertainty in the ground shaking levels that are appropriate for design, with the concomitant economic effects of potential underdesign (resulting in needlessly high damage levels) or overdesign (resulting in needless construction costs)
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From page 153... ...
The earthquake risk in the United States is growing at an alarming rate, even in the face of the remarkable advances in earthquake science and engineering (EERI, 2003)
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From page 154... ...
Our understanding of the nature of earthquake hazards in the United States -- the distribution, frequency, and severity of damaging ground shaking -- is based on past damaging earthquakes as well as on the tens of thousands of small earthquakes that occur throughout the nation each year. Improved seismic monitoring networks will provide the basis for better characterization of this seismicity, so that the ground motion prediction models that underpin building codes and earthquake engineering design -- the basis for safeguarding life and property -- can more accurately reflect the complex nature of the hazard.
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From page 155... ...
earthquake hazard information should be continued to track the growth of seismic risk in the United States, thereby further reducing the uncertainty associ ated with seismic risk. The guidelines, standards, and codes available to earthquake engineers for the design of new structures and the rehabilitation of existing structures hold promise for protecting lives and the built environment against the largest expected earthquakes.
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From page 156... ...
These assumptions relate to the value of the built environment within the United States, the cost of seismic rehabilitation and the number of existing buildings that need strengthening, and the annual expected loss from earthquakes compared with reduced losses when higher seismic design standards based on information from improved monitoring are applied. These calculations indicate a total loss avoided of more than $140 million per year, based on an estimate of reduced earthquake losses together with estimates of savings in construction costs that would accrue from the implementation of performance-based engineering design in those regions where improved seismic monitoring indicates that seismic design standards can be reduced.
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From page 157... ...
The extent of the assumptions required to make the ballpark calculations for performance-based engineering design emphasizes the need for additional quantitative information before more precise estimates of the economic benefits of seismic monitoring can be determined. After every damaging earthquake in the United States, data gathering and applied research should be sponsored -- as a collaborative activity among the National Earthquake Hazards Reduction Program (NEHRP)
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From page 158... ...
158 IMPROVED SEISMIC MONITORING -- IMPROVED DECISION-MAKING the estimated losses. It is reasonable to conclude that mitigation actions -- based on improved information and the consequent reduction of uncertainty -- would yield benefits amounting to several times the cost of improved seismic monitoring.
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