Molly Jackman et al at Facebook: “After a natural disaster, humanitarian organizations need to know where affected people are located, what resources are needed, and who is safe. This information is extremely difficult and often impossible to capture through conventional data collection methods in a timely manner. As more people connect and share on Facebook, our data is able to provide insights in near-real time to help humanitarian organizations coordinate their work and fill crucial gaps in information during disasters. This morning we announced a Facebook disaster map initiative to help organizations address the critical gap in information they often face when responding to natural disasters.
Facebook disaster maps provide information about where populations are located, how they are moving, and where they are checking in safe during a natural disaster. All data is de-identified and aggregated to a 360 square meter tile or local administrative boundaries (e.g. census boundaries). 
This blog describes the disaster maps datasets, how insights are calculated, and the steps taken to ensure that we’re preserving privacy….(More)”.