Wednesday, August 06, 2008

California Postearthquake Information Clearinghouse

The California Information Clearinghouse was formally established in a directive signed by governor Ronald Reagan following the magnitude 6.5 San Fernando earthquake in 1971. The purpose of the clearinghouse is to systematize the collection of critical, often ephemeral, data from field investigations to promote its use by emergency managers during the response and recovery phases following damaging earthquakes and to archive this data for use by researchers in producing a more methodical analysis of earthquakes and their impacts.

The Southern USGS California multihazards project and clearing house runs fire data in ArcGIS Server to create fire perimeter map.

The clearinghouse has grown to include more than a dozen federal, state, academic, and nongovernmental organizations, though management falls to just four: the California Geological Survey (CGS), California Office of Emergency Services (OES), Earthquake Engineering Research Institute (EERI), and U.S. Geological Survey (USGS). While the clearinghouse concept has been implemented during other disasters, such as 9/11 and Hurricane Katrina, the California Information Clearinghouse itself remains focused on earthquakes.

GIS has long had an important role in the clearinghouse as a way to integrate the variety of field data collected by geologists and engineers. Following the magnitude 6.7 Northridge earthquake in 1994, OES supported a mobile GIS lab that ran 24/7, which allowed each day's data to be incorporated overnight into maps that were available to researchers to guide the next day's fieldwork. The clearinghouse was colocated with the Regional Emergency Operations Center (REOC), which simplified sharing the results of these investigations with emergency responders.

In recent years, the advent of mobile GIS has dramatically improved the way the field scientists gather and share postearthquake information. In the past, geologists from USGS and CGS gathered such information in three different paper forms. A liquefaction form was used to gather data about how the soil behaved during strong shaking, noting any evidence of liquefaction, such as sunken structures or sand volcanoes. Another form was used to describe earthquake-induced landslides. A third form recorded geologic parameters of ground ruptures, such as how much offset occurred along the fault, the angles of fault movement, and any secondary cracks or movements that occurred away from the fault. If a GPS unit was available, the location coordinates could also be written down on the form. Otherwise, a dot on a topographic map became the location for these observations. Incorporating this data into a GIS usually required the help of a GIS specialist and a delay of hours or days.

Now geologists from both USGS and CGS can enter the same field data into a GIS running on a handheld device, using an attached GPS to automatically provide location coordinates. Luke Blair of USGS, a longtime user of ESRI GIS software, designed the mobile versions of the three forms. Each is written as simply as possible so that someone who has never used GIS can easily record information. The user can toggle between the three types of forms depending on the situation.

Every data entry into ArcPad instantly has a GPS latitude and longitude point attached to it. When the digital data is uploaded at the office, it can be immediately input into the geodatabase for the event and processed in GIS. The clearinghouse GIS worker is then able to quickly produce an online map. "We are looking to step into the new generation of technology with ArcGIS Server," says Blair. "Ultimately, this would make it possible for data to be wirelessly sent live from the field for map production and analysis for both scientists and first responders."

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