The Haitian government has estimated it will take 10 years and $3 billion to repair the damage caused by Jan. 12’s magnitude-7 earthquake, although some warn it may cost more than three times that amount.

By the time a United Nations–hosted international donors conference convenes in New York City in late March, planners expect to greatly refine the estimate, thanks in part to social networking.

An assessment based on high-resolution satellite and aerial imagery was commissioned after the quake by the World Bank and the Global Facility for Disaster Reduction and Recovery, which supports U.N. efforts for disaster reduction. The firm asked its consultant, ImageCat Inc., Long Beach, Calif., to call on a consortium of organizations, companies and volunteer earthquake experts to activate a remote damage-assessment system called GEO-CAN, which stands for “Global Earth Observation Catastrophe Assessment Network.”

“For the first time we involved hundreds of engineers and scientists from across the world, in a distributed way, to make determinations based on high-resolution imagery made available by Microsoft, Google, and World Bank-ImageCat-RIT remote sensing mission,” says Shubharoop Ghosh, vice president at ImageCat.

“It was pretty amazing, the whole social networking with engineers,” says Marjorie Greene, special projects manager at the Earthquake Engineering Research Institute (EERI) in Oakland, Calif. “ ‘Ground-truthing’ with field reports is our next step,” she says.

Technical experts representing the World Bank, the American Development Bank, the European Commission and the U. N. began ground surveys on Feb. 9.

The image assessment went off in two phases. The first was a rapid assessment based on satellite images to identify blocked roads and damaged bridges and establish the extent of destruction. Phase two involved distribution of additional high-resolution aerial images of the same area to the volunteer experts for a systematic, building-by-building evaluation.

Over the weekend of Jan. 23-24, more than 500 individual experts from 131 organizations and 23 countries pitched in to examine 776 sq. miles in and around Port-au-Prince and identify heavily damaged and collapsed buildings. By the end of the weekend, 10,797 had been tagged in a geographic information database.

“That was really good,” says participant William L. “Bill” Mumbleau, vice president for corporate GIS at the Kleinfelder Group, San Diego. “I don’t think we could have done a better job [if we were] on the ground at this point—I would consider it an impedance. There is too much going on with the rescue and the need to get people into shelters.”

ImageCat managed the image distribution and collected and processed the data. “This was the first time the earthquake engineering community came together this way,” says Ghosh, who credited 62 universities and 18 institutions for helping to put out the word for volunteers. They came from academia and private industry in droves, with 58 engineering and consulting firms listed as participants. “That’s why it’s so unique—this whole idea of ‘crowd-sourcing’ involved communities,” Ghosh says.

Ghosh says the experts were sent to ImageCat’s “Virtual Disaster Viewer” site and given passwords to check out layered grid tiles of the damage area. Each grid carries not only post-quake, high-resolution, 15-cm/pixel aerial and satellite images, but also pre-quake images to compare a building’s condition before and after the event as well as distinguish a historic ruin from a new one. The experts outlined building footprints, identifying them as geo-referenced objects to which data could be attached. They added condition scores and annotations and e-mailed the files back to ImageCat to add to the database.

Mumbleau says the analysts also were on the lookout for facilities, particularly in more remote areas, that might be sound enough to use for staging areas or shelter. Sometimes the damage was obvious, as in the total destruction of the Hotel Montana (pictured right), but other evidence was subtle, such as buildings out of alignment with historic images, suggesting they were off their foundations.

The idea to create a social-networking platform to analyze a huge amount of remotely acquired disaster data came from a consortium that included U.K.-based Earthquake Engineering Field Investigation Team; University College London’s Earthquake and People Interaction Centre; the U.K. government’s Engineering and Physical Sciences Research Council; U.S.-based EERI, and the Multidisciplinary Center for Earthquake Engineering Research at the State University of New York at Buffalo.

The technology and protocols were first tested after the 2008 Wenchuan, China, earthquake in eastern Sichuan. ImageCat, with Microsoft and its Virtual Earth product, launched the Virtual Disaster Viewer site to distribute satellite imagery for public viewing and for non-profit organizations and researchers. EERI’s Greene says, however, satellite imagery alone was not enough for the kind of the building-by-building analysis engineers needed to do. That’s why GEO-CAN was designed to go off in phases, adding high-resolution aerial photos as they were fed into the system. The next goal is to incorporate oblique aerial images, which show building facades and can help engineers estimate volume and square footage lost in a disaster.

ImageCat started tracking the phase-two assessments at the end of the day on Jan. 21 when 576 structures had been tagged as either heavily damaged (147) or collapsed (429). By the end of the following day the network had tagged 4,391 buildings in such condition. By Feb. 8 the total stood at 21,112.