CATS Earthquake

Earthquake

Earthquake Module

Performs analyses based on the geology of the region

Uses the earthquake ground motion model created by the US Geological Survey

Provides estimates of structural damage levels, including light, moderate, & severe

Estimates shaking damage probability levels for a wide range of structural types

Experience in the United States has shown that because of broken lines of communication, it is difficult to obtain an immediate estimate of earthquake damage. In an effort to provide one, CATS has incorporated an earthquake model developed by the United States Geological Survey (USGS).

The earthquake model requires a minimum of information in order to run: the location of the earthquake's epicenter, its magnitude, the geometry of the fault rupture, and the surface geology where the earthquake struck (provided in the form of a digital geological database). CATS' user interface automatically inputs this information from the USGS Internment site and digitized fault lines. When the model output is merged with the resource, population, and housing databases in the GIS, emergency managers can quickly estimate the extent of expected and probabilistic damage, and anticipate the requirements for relief. Example model output for the 1994 Northridge earthquake is shown below:

Sample CATS Earthquake Model Run for the Northridge Earthquake, January 1994 The figure displays the spatial distribution of damage to single family homes. The red, yellow, and blue areas represent areas of severe, moderate, and light damage, respectively. Green areas designate actual building damage as determined by on-site inspectors, indicating excellent agreement between actual damage and damage predicted by CATS.

On the morning of the earthquake in the Northridge section of Los Angeles, FEMA and DSWA (then DNA) used CATS to assess the extent of the damage. The CATS earthquake module, using bulletins issued by the USGS National Earthquake Information Center in Boulder, Colorado, calculated the Modified Mercalli Intensity (MMI) of the earthquake ground shaking throughout the affected area. The MMI shaking intensities, like the dynamic pressures of a hurricane, are associated with various levels of damage, and the CATS earthquake module, like the hurricane winds module, constructed deterministic and probabilistic damage bands. CATS' GIS then determined the population and critical resources at risk in the affected areas. CATS predicted that 560,000 households would need assistance; 600,000 actually applied for help, thus proving the accuracy of CATS' consequences assessment capabilities.