Improved Seismic Monitoring - Improved Decision-Making Assessing the Value of Reduced Uncertainty (2006) / Chapter Skim
Currently Skimming:
1 Introduction
1 Introduction
Pages 9-41
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 9... ...
include repair and replacement costs for structural and nonstructural components, building content loss, business inventory loss, and direct business interruption losses.
|
From page 10... ...
For example, improved seismic monitoring has the potential to improve current estimates of earthquake frequencies, of the median level of ground motion attenuation models (relating earthquake magnitude and distance to ground shaking levels) , and of the median level of fragility models (relating ground shaking levels to building 3As estimated from HAZUS-MH (FEMA, 2004)
|
From page 11... ...
Improved seismic monitoring has the potential to provide more accurate estimates of aleatory variability -- with implications for seismic design practice-because current building codes are based on a ground shaking level that has a 1/2,500 annual probability of occurrence, a level that is strongly influenced by aleatory variability in ground motion models. Improved seismic monitoring also has the potential to provide more accurate estimates of aleatory variability in earthquake frequencies and in fragility models.
|
From page 12... ...
Building on a foundation that was established following the 1964 Prince William Sound earthquake in Alaska and intensified after the 1971 San Fernando earthquake in California, the NEHRP was enacted by Congress in 1977 as the federal government's coordinated approach to addressing earthquake risks in the United States. The program is managed as a collaborative effort among the Federal Emergency Management Agency (FEMA)
|
From page 13... ...
Further, these systems have limited dynamic range, meaning that they cannot record the ground motions of large- or moderate-sized earthquakes that are located close to the recording station. In contrast, modern digital seismic stations typically have broadband seismic sensors that are sensitive to a very broad range frequency band (typically 20 to 0.01 Hz)
|
From page 14... ...
EXISTING AND PROPOSED SEISMIC NETWORKS Seismic monitoring activities in the United States today are based on a patchwork of regional seismic networks (see Figure 1.1) that use varying seismic instruments, often with limited fidelity and dynamic range.
|
From page 15... ...
was based on relative seismic risk -- a function of the population potentially exposed to strong ground shaking and the potential severity of that shaking. Existing Weak Motion Monitoring Networks There are approximately 1,700 stations5 in the United States equipped with conventional weak motion seismic instruments (Figure 1.1)
|
From page 16... ...
· Replacement of 1,000 aging analog seismograph stations operating in regional seismic networks with modern digital instruments ($34.5 million) · Installation of 3,000 ground-based, modern, digital strong motion seismographs in more densely populated areas at risk of strong ground shaking ($62 million)
|
From page 17... ...
. Of these sites, approximately 200 are operated by regional seismic networks and the remainder are operated either by organizations that specialize in strong motion recordings (e.g., the California Strong Motion Instrumentation Program)
|
From page 18... ...
18 United the throughout colors) different by (marked networks seismic and (dots)
|
From page 19... ...
19 throughout colors) different by (marked networks seismic and (dots)
|
From page 20... ...
Similarly, because of the small number of strong motion stations located in structures, few owners will have the benefit of a "proof test" -- knowing the relationship between the level of ground shaking experienced by the structure and the level of ground motion for which it was designed. An ideal level of seismic monitoring -- the ultimate extension of the present ANSS proposal-would permit the identification of ground shaking hot spots and provide for the proof-testing of all critical and economically significant structures and lifelines in all seismically active urban regions of the country.
|
From page 21... ...
The principal goal of ANSS is earthquake monitoring, an evolutionary and ongoing activity with a primary focus on continuously improved quantification of earthquake hazards. USArray, on the other hand, is a one-time comprehensive examination of the deep structure of the crust and upper mantle, primarily for research purposes.
|
From page 22... ...
As both seismic monitoring programs -- ANSS and the monitoring component of EarthScope -- are implemented, there is an evolving relationship between the programs. One example is the location of PBO facilities within regional seismic networks to allow sharing of telemetry and maintenance costs.
|
From page 23... ...
(Chapter 6) Strong Motion Building/Lifeline Monitoring Records: Performance Improved emergency response planning in/on structures Assessment (Chapter 7)
|
From page 24... ...
This system, which was in place and operating at the time of the earthquake, provided notification of the magnitude, location, strong motion data, and an instrumental intensity map to 247 organizations nationwide within 2 minutes of the earthquake through paging, fax, and the Internet. These organizations included all fire and police agencies at the local, regional, and national government levels; ministries with emergency response and recovery functions; dam and nuclear power plant managers; scientists; and the news media.
|
From page 25... ...
based ShakeMaps, an internet-based real-time map information product generated by the USGS, show the location of strong ground shaking within minutes to tens of minutes after an event. The economic benefits for emergency response derived from the products of improved seismic monitoring, such as ShakeMaps, are discussed in more detail in Chapter 7.
|
From page 26... ...
These costs include the following: · the costs of maintaining and operating the nation's existing seismic monitoring networks, including present federal contributions to the ANSS as well as nonfederal contributions to the plethora of state, university, and private networks now included within the ANSS; · the costs of expanding the nation's monitoring, particularly with the deployment of modern digital seismographs as part of the full ANSS proposal, and the operational and maintenance costs after the instrumentation is in place; and · a component of the seismic monitoring costs of EarthScope, representing those costs associated with the permanent "backbone" network of seismographic stations and the PBO regional borehole seismic network. Financial support for the present system of seismic monitoring networks is complex.
|
From page 27... ...
; military and DOE monitoring related primarily to nuclear test verification; research monitoring (e.g., monitoring components of the EarthScope initiative) ; earthquake monitoring required for regulatory compliance (e.g., dams, nuclear power facilities)
|
From page 28... ...
. In general, losses or costs associated with earthquakes fall into five major categories -- direct physical damage, induced physical damage, human impacts, costs of response and recovery, and business interruption and other economic losses.
|
From page 29... ...
. Nevertheless, the aggregate cost of direct physical damage has been estimated or measured in most recent earthquake events in the United States, as well as for some major historical events in other parts of the world (e.g., Tables 1.2 and 1.3)
|
From page 30... ...
. BOX 1.4 The Costs of Electricity Disruption from Earthquakes The results of two in-depth studies following the Northridge Earthquake shed some light on direct and indirect business interruption losses from electricity lifeline disruptions.
|
From page 31... ...
in some sectors. Rose and Lim also used an input-output model to determine indirect business interruption losses from the electricity outage.
|
From page 32... ...
While the direct costs for the repair and replacement of earthquake-damaged lifeline facilities have been significant, there have also been very high indirect costs due to impaired infrastructure. One study of the 1994 Northridge earthquake included estimates of $6.5 billion of business interruption costs, of which $1.5 billion was ascribed to transportation network disruptions (Gordon et al., 1998)
|
From page 33... ...
Treatment FIGURE 1.5 Injuries and deaths in the 1994 Northridge earthquake. Figures marked with asterisks indicate numbers of households; other numbers refer to individuals.
|
From page 34... ...
However, during the past decade there has been a heightened awareness that other types of losses that may result from physical damage as well as other causes -- such as direct and indirect business interruption, and environmental and social impacts -- must also be considered (Mileti, 1999; NRC, 1999; Heinz Center, 2000; Ganderton, 2005)
|
From page 35... ...
The 1994 Northridge earthquake is the best-documented earthquake event in U.S. history, providing an illustration of the magnitude of both direct and indirect costs.
|
From page 36... ...
, consisting of $3.5 billion per year in capital losses (building repair, lost contents and inventory) and $0.9 billion per year in income losses related to building damage (e.g., rental income losses, wage losses, business interruption)
|
From page 37... ...
Although it did not define the benefits of improved seismic information, a 1973 report contained an early and clear recognition that hazard reduction is beneficial to society (NRC, 1973)
|
From page 38... ...
. BOX 1.5 Building Codes and Earthquake Loss Reduction Building codes have been recognized as one of the most effective tools for mitigating earthquake losses.
|
From page 39... ...
Comprehensive rehabilitation: the building stock is rehabilitated to the current seismic design levels for the region Comprehensive Baseline Rehabilitation Southern Building or contents $69.5 billion $51.3 billion California damage Mw 7.0 Business interruption $16 billion $6.1 billion Newport- Displaced people ~400,000 93,000 Inglewood Fault Shelter ~100,000 ~29,000 San Francisco Building or contents $32.6 billion $22.2 billion Bay damage Mw 7.0 Business interruption $7 billion $2.5 billion Hayward Fault Displaced people ~140,000 40,000 Shelter ~30,000 ~9,000 For these two examples, a comprehensive rehabilitation program could reduce building and contents damage losses more than 25 percent and business interruption losses by more than 60 percent. Major injuries and deaths, numbers of displaced people, and those requiring short-term shel ter would also be reduced by more than 70 percent.
|
From page 40... ...
In addition, the analysis of seismic monitoring costs is focused on earthquake-related monitoring -- strong motion instrumentation and that component of weak motion instrumentation related to distant earthquakes. BOX 1.6 Statement of Task An NRC ad hoc committee will provide advice regarding the economic benefits of improved seismic monitoring, with particular attention to the benefits that could derive from implementation of the Advanced National Seismic System (ANSS)
|
From page 41... ...
Although the specific charge to the committee was to evaluate the economic benefits of seismic monitoring, it was clear to the committee that decisions regarding the allocation of resources for improved seismic monitoring must also take into account the costs of improved monitoring. Accordingly, some measures of the cost-effectiveness of seismic monitoring are presented in this report.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.