New Findings: Rapid Assessment of Disaster Damage Using Social Media

The latest peer-reviewed, scientific research on social media & crisis computing has just been published in the prestigious journal, Science. The authors pose a question that many of us in the international humanitarian space have been asking, debating and answering since 2009: Can social media data aid in disaster response and damage assessment?

To answer this question, the authors of the new study carry out “a multiscale analysis of Twitter activity before, during, and after Hurricane Sandy” and “examine the online response of 50 metropolitan areas of the US.” They find a “strong relationship between proximity to Sandy’s path and hurricane-related social media activity.” In addition, they “show that real and perceived threats, together with physical disaster effects, are directly observable through the intensity and composition of Twitter’s message stream.”

What’s more, they actually “demonstrate that per-capita Twitter activity strongly correlates with the per-capita economic damage inflicted by the hurricane.” The authors found these results to hold true for a “wide range of [US-based] disasters and suggest that massive online social networks can be used for rapid assessment of damage caused by a large-scale disaster.”

Unlike the vast majority of crisis computing studies in the scientific literature, this is one of the few (perhaps the only?) study of its kind that uses actual post-disaster damage data, i.e. actual ground-truthing, to demonstrate that “the per-capita number of Twitter messages corresponds directly to disaster-inflicted monetary damage.” What’s more, “The correlation is especially pronounced for persistent post-disaster activity and is weakest at the peak of the disaster.”

The authors thus conclude that social media is a “viable platform for preliminary rapid damage assessment in the chaotic time immediately after a disaster.” As such, their results suggest that “officials should pay attention to normalized activity levels, rates of original content creation, and rates of content rebroadcast to identify the hardest hit areas in real time. Immediately after a disaster, they should focus on persistence in activity levels to assess which areas are likely to need the most assistance.”

In sum, the authors found that “Twitter activity during a large-scale natural disaster—in this instance Hurricane Sandy—is related to the proximity of the region to the path of the hurricane. Activity drops as the distance from the hurricane increases; after a distance of approximately 1200 to 1500 km, the influence of proximity disappears. High-level analysis of the composition of the message stream reveals additional findings. Geo-enriched data (with location of tweets inferred from users’ profiles) show that the areas close to the disaster generate more original content […].”

Five years ago, professional humanitarians were still largely dismissive of social media’s added value in disasters. Three years ago, it was the turn of ivory tower academics in the social sciences to dismiss the value added of social media for disaster response. The criticisms focused on the notion that reports posted on social media were simply untrustworthy and hardly representative. The above peer-reviewed scientific study dismisses these limitations as inconsequential.