Seismic risk
Encyclopedia
Seismic risk uses the results of a seismic hazard
analysis, and includes both consequence and probability. Seismic risk has been defined, for most management purposes, as the potential economic, social and environmental consequences of hazardous events that may occur in a specified period of time. http://www.unisdr.org/HFdialogue/download/tp3-paper-urban-seimic-risk.pdf A building located in a region of high seismic hazard is at lower risk if it is built to sound seismic engineering principles. On the other hand, a building located in a region with a history of minor seismicity, in a brick building located on fill subject to liquifaction can be as high or higher risk.
A special subset is urban seismic risk
which looks at the specific issues of cities. Risk determination and emergency response can be also be determined through the use of an Earthquake scenario
.
Seismic risk is often determined using a seismic modeling computer programs which uses the seismic hazard inputs and combines them with the known susceptibilities of structures and facilities, such as buildings, bridges, electrical power switching stations, etc. The result gives probabilities for economic damage or casualties, for example the HAZUS computer program http://www.fema.gov/plan/prevent/hazus/. While the results can be used as a general measure of seismic risk for types of buildings, the actual seismic risk for any individual building may vary considerably and will depend upon its exact configuration and condition. Acquiring and analyzing the specific data for an individual building or facility is one of the most expensive and daunting aspects of seismic risk estimation. Progress is made if one can calculate the 'fragility' or seismic capacity of the components within a structure. http://fire.nist.gov/bfrlpubs/build98/PDF/b98106.pdf
Seismic hazard
Seismic hazard refers to the study of expected earthquake ground motions at the earth's surface, and its likely effects on existing natural conditions and man-made structures for public safety considerations; the results of such studies are published as seismic hazard maps, which identify the...
analysis, and includes both consequence and probability. Seismic risk has been defined, for most management purposes, as the potential economic, social and environmental consequences of hazardous events that may occur in a specified period of time. http://www.unisdr.org/HFdialogue/download/tp3-paper-urban-seimic-risk.pdf A building located in a region of high seismic hazard is at lower risk if it is built to sound seismic engineering principles. On the other hand, a building located in a region with a history of minor seismicity, in a brick building located on fill subject to liquifaction can be as high or higher risk.
A special subset is urban seismic risk
Urban seismic risk
Urban seismic risk is a subset of the general term seismic risk which describes the problems specific to centers of population when they are subjected to earthquakes. Many risks can be minimised with good earthquake construction, and seismic analysis...
which looks at the specific issues of cities. Risk determination and emergency response can be also be determined through the use of an Earthquake scenario
Earthquake scenario
Earthquake scenario is a planning tool to determine the appropriate emergency responses or building systems in seismic risk areas. It uses the basics of seismic hazard studies, but usually places a set earthquake on a specific fault, most likely near a high-population area...
.
Determination of seismic risk
The determination of seismic risk is the foundation for risk mitigation decision-making, a key step in risk management. Large corporations and other enterprises (e.g., local governments) analyze their 'portfolio' of properties, to determine how to best allocate limited funds for structural strengthening of buildings, or other risk reduction measures such as emergency planning. In calculating the risk of each facility in the 'portfolio', potential life safety and economic losses due not only to structural damage, but also to equipment, contents and business interruption are considered. Public agencies (local, state governments and federal agencies) similarly analyze their portfolios. The interconnections of infrastructures such as water, road and highway, and electric power systems are also considered. Insurance companies routinely employ estimates of seismic risk in their operations, to determine appropriate insurance rates, to monitor over-accumulation of policies in a small area, and to purchase reinsurance. A simplified method of calculating seismic risk for a given city, involves the use of a street survey. http://www.uni-kassel.de/fb14/stahlbau/eartheng/downloads/part1.pdf If you know the level of seismic hazard, the damage generally follows established patterns.Seismic risk is often determined using a seismic modeling computer programs which uses the seismic hazard inputs and combines them with the known susceptibilities of structures and facilities, such as buildings, bridges, electrical power switching stations, etc. The result gives probabilities for economic damage or casualties, for example the HAZUS computer program http://www.fema.gov/plan/prevent/hazus/. While the results can be used as a general measure of seismic risk for types of buildings, the actual seismic risk for any individual building may vary considerably and will depend upon its exact configuration and condition. Acquiring and analyzing the specific data for an individual building or facility is one of the most expensive and daunting aspects of seismic risk estimation. Progress is made if one can calculate the 'fragility' or seismic capacity of the components within a structure. http://fire.nist.gov/bfrlpubs/build98/PDF/b98106.pdf
Reduction of seismic risk
Seismic risk can be reduced by active programs that improve emergency response, and improve basic infrastructure. The concepts of earthquake preparedness can help plan for emergencies arising from an earthquake. Building codes are intended to help to manage seismic risk and are updated as more is learned about the effects of seismic ground motion on buildings. However, the changes generally do not immediately improve seismic risk in a community since existing buildings are rarely required to be upgraded to meet the revisions.External links
- C. Allin CornellC. Allin CornellC. Allin Cornell is a civil engineer who made important contributions to reliability theory and earthquake engineering and, along with Dr. Luis Esteva, developed the field of Probabilistic Seismic Hazard Analysis in 1968....
- HAZUS - Seismic Risk Program for the US
- An All HAZUS Web Space
- HAZUS Community website
- Infrastructure Risk Research Project at The University of British Columbia, Vancouver, Canada
- OIKOS - Educational European project based on Google Maps Mashups