The city of Berkeley, California, located on the eastern shore of San Francisco Bay, is a quaint town of 100,000 people. Historic Arts & Crafts bungalow homes and gardens are nestled along charming tree-lined streets. Home to the University of California, Berkeley—the University of California system's oldest campus—the city maintains its heritage as an intellectual center and offers a rich international cultural and social landscape. Residents and tourists can enjoy the city's amenities in mild climate year-round.

Like many cities in California, Berkeley has areas located within earthquake fault rupture and seismic hazard zones, with many fault lines running near or through its boundaries. Because earthquakes are inevitable in this seismically active region, the city was actively prepared to respond during and after earthquakes. In 2002, Arrietta Chakos of the city manager's office, spearheaded Berkeley's effort to comply with the Disaster Mitigation Act of 2000 (www.ci.berkeley.ca.us/manager/disastermitigation.html), an initiative to "establish a national program for pre-disaster mitigation and streamline administration of disaster relief." Government entities that file a mitigation plan with their state for coordination and approval by the Federal Emergency Management Agency (FEMA) are eligible to receive federal matching funds more quickly in the event of a disaster.

To support Berkeley's disaster mitigation planning, Brian Quinn, an applications programmer/analyst in the GIS division of Berkeley's Information Technology Department, acquired HAZUS, a GIS-based natural hazard loss estimation methodology software program from FEMA that estimates hazard-related damage to plan before and respond after disaster events. Loss estimations are important input for mitigation plan development, emergency preparedness, and response and recovery planning.

"We knew that the raster data stored in our geodatabase would enhance our ability to fully implement HAZUS," states Quinn. "We had been building our enterprise GIS for several years and populated the geodatabase with raster basemaps needed by city employees and residents." The city's GIS manager, Patrick DeTemple, chose ArcView in the mid-1990s for its ease of use and soon found that it served the city's desktop GIS needs very well. To support the city's expanding GIS requirements, he then obtained an ArcInfo license and began staffing to build to an enterprise GIS.

ERDAS IMAGINE, from Esri Business Partner Leica Geosystems GIS & Mapping, was chosen by Quinn for its georeferencing and mosaicking tools. The close integration of ArcInfo and ERDAS IMAGINE allowed Quinn and others to quickly build and populate the city's ArcSDE geodatabase with local and regional imagery and planning and engineering drawings that serve as the foundation for all city GIS-related activities, including the HAZUS implementation and disaster mitigation planning.

Prior to 2002, the city used digital orthophotography, which was captured in four different years, for its basemaps. Employees utilized shapefiles and paper index maps for each date to identify which image tile was needed for their work. To improve this slow and inefficient process, Quinn created a centralized raster geodatabase to enable end users to easily access seamless imagery via customized ArcIMS map services.

Using ERDAS IMAGINE, photo tiles were unpacked into a directory and mosaicked into a seamless image. Next, the image was loaded into the geodatabase using ArcSDE. Quinn explains, "This raster data is the foundation of our geodatabase, like ballast to a ship."

Quinn elaborates, "Our geodatabase holds five mosaics at 30-cm or smaller pixel size between 1996 and 2003. We have regional mosaics from United States Geological Survey (USGS) and National Geospatial-Intelligence Agency (NGA) imagery."

For regional context, Quinn downloaded 550 orthophoto quarter quadrangles from the California Spatial Information Library mirror site (casil.ucdavis.edu/casil/usgs.gov), obtained USGS-NGA 30-cm natural color imagery from USGS and used ERDAS IMAGINE to build seamless mosaics from each data set. The results were 24 GB grayscale and 170 GB natural color mosaics for the San Francisco Bay area to be used by GIS analysts and hazard modelers within Berkeley and beyond the city boundaries.

"Obtaining and processing the regionwide data," says Quinn, "were driven by our disaster mitigation planning needs because disasters outside the city can affect our residents. By geocoding employee home locations, many of which are outside Berkeley's boundaries, we show that our city government depends on other parts of our region. While many workers live near Berkeley, key employees may live in suburbs outside the city near the Calaveras Fault or elsewhere along the Hayward Fault. A large event beyond our boundaries could challenge our ability to deliver services."

With the basemapping complete, Quinn began preparing geohazard data for input into the HAZUS model to further support development of the city's disaster mitigation plan. Using the ArcGIS Spatial Analyst extension, Berkeley's 25,000 parcel polygons were converted to a one-meter raster grid.

"Each grid cell was assigned a zone ID number based on the parcel it was most within," explains Quinn. "Next, using the ArcGIS Spatial Analyst extension, we began the process of overlaying these 25,000 parcel zones on three USGS hazard grids, including seismic hazard grids, seismic landslide hazard grids, and slope failure grids. Precise alignment of our parcels with the various hazard grids created accurate results."

"The analytical process is identical for each gridded hazard," explains Quinn. "The Spatial Analyst Raster Calculator was used to calculate the maximum, minimum, median, and many statistical variations of the underlying hazard potential for each raster zone, providing unique results for each Berkeley parcel." Quinn also flagged parcel features using earthquake fault rupture and seismic hazard zone polygons from the California Geological Survey.

Quinn continues, "Our ArcIMS interactive map services allow city planners and the public to view individual parcel risks. The Emergency Operations Center has used HAZUS shaking models to estimate potential earthquake damage on each individual block of the city. The HAZUS software allows us to estimate the potential consequences of specific earthquake scenarios or estimate annualized loss from USGS seismic risk models. For example, we can estimate the impact of an earthquake in terms of likely injuries and deaths, patterns of building collapse, need for shelters, and how much monetary damage may result. Patterns in these estimates serve as inputs to the mitigation plan."

Quinn runs the various disaster scenario models as part of mitigation planning to inform the city's emergency manager about citywide patterns of potential earthquake damage and to illustrate how conditions change from one scenario to another.

For more information, contact Brian B. Quinn, Ph.D. (e-mail: bbq@ci.berkeley.ca.us or hazard@craiova.com), or visit the city of Berkeley's spatial data portal (www.ci.berkeley.ca.us/gis).

For more information on geospatial solutions, contact Leica Geosystems (toll free in the United States: 1-877-463-7327 or outside the United States: 404-248-9000) or visit Leica Geosystems at gis.leica-geosystems.com.