Quick-and-Wide Propagation of Disaster Tweets: Why It Matters and How to Measure It

As dynamic, non-routine disaster events appear and disappear in a short period, quickly and widely disseminating emergency warnings and alerts to the public is a critical communication goal for emergency management officers and citizen journalists. Twitter has become a prominent communication medium to achieve such a communication goal, attracting academic scholars, government agencies, and industry practitioners. However, most academic research and government reports have relied on either the retweet count or retweet time to understand factors affecting the propagation of disaster information. We argue that neither measure is sufficient to reflect the extent to which disaster tweets are quickly and widely propagated. Hence, we propose a new measure called the Propagation Index (PI) to better evaluate quick and wide propagation of disaster information. Using two Twitter datasets, we empirically examine the proposed measure in association with the Twitter features and compare its statistical results with those of the retweet count and retweet time. Our findings suggest that the PI more accurately captures how quickly and widely disaster tweets are propagated than the other measures. Therefore, this study contributes to academia, governments, and industry to improve their understanding of the propagation of disaster information on Twitter.