By: B. J. Solomon, N. Storey, I. G. Wong, W. J. Silva, N. Gregor, D. Wright, and G. N. McDonald
Large earthquakes can disrupt lives with devastating effects on communities and individuals. An important step in characterizing the risk posed by a large earthquake is to map accompanying geologic hazards. Hazard maps can provide the geologic basis for a comprehensive loss estimate using computer software such as HAZUS (which stands for Hazards U.S.), developed for the Federal Emergency Management Agency (FEMA) by the National Institute of Building Sciences (1999). The estimate, including losses from geologic effects, may describe the scale and extent of damage and disruption, with quantitative estimates of the casualties and costs for repair and replacement of damaged buildings and facilities, losses of function for critical facilities, and the extent of induced hazards such as fire, flood, or contamination by hazardous materials. The estimate and hazard maps can then be used to increase awareness and improve emergency-response planning and preparedness.
The purpose of this report is to discuss and map geologic hazards that may result from a scenario earthquake of moment magnitude (M) 7 on the Salt Lake City segment of the Wasatch fault zone. Our mapping procedures, using Geographic Information System (GIS) software, modify default methods included with HAZUS. Our modifications include recently published relationships based on the effects of historical earthquakes worldwide and techniques allowing the use of existing surficial geologic data in a regional study. Our analysis begins with calculating ground motions associated with the scenario earthquake, a key factor for mapping geologic hazards induced by strong ground shaking. The resultant earthquake-hazard maps can be used to estimate the consequences of our scenario earthquake to the central Wasatch Front.
Emergency-response planners can use the 1:250,000-scale hazard maps with software such as HAZUS to estimate the consequences of the scenario earthquake. This estimate may describe the extent of damage and disruption, approximate number of casualties, repair and replacement costs, losses of function for critical facilities, and extent of induced hazards, providing an important tool for emergency-response planning and preparedness.
Pages: 59 p.
Plates: 6 pl.
Location: Salt Lake County