In February 2011, Christchurch was struck by a severe earthquake that killed 185 people and caused significant disruption and damage to large portions of a city already weakened by an earlier earthquake. In the response to the quake, volunteers and officials at the recovery agencies used open data, open source tools, trusted data sharing and crowdsourcing to develop a range of products and services required to respond successfully to emerging conditions. These included a crowdsourced emergency information Web app that generated 70,000 visits within the first 48 hours after the earthquake; a series of geographic information system (GIS) data sharing agreements between agencies that enabled the successful provision of mapping services throughout the response and recovery; websites using open property data that enabled citizens to check the status of their homes and land, and generated millions of hits within hours of release; a construction intention viewer built using open data and open source tools that saved NZ$4 million in construction costs within its first year of use; and a crowdsourced competition for school children that generated over 18,000 new building footprints for open property databases at a cost of $0.02 per footprint.