The challenge of nowcasting the effect of natural hazard events (e.g., earthquakes, floods, hurricanes) on assets, people and society is of primary importance for assessing the ability of such systems to recover from extreme events. Traditional recovery estimates, such as surveys and interviews, are usually costly, time consuming and do not scale. Here we present a methodology to indirectly estimate the post-emergency recovery status (downtime) of small businesses in urban areas looking at their online posting activity on social media. Analysing the time series of posts before and after an event, we quantify the downtime of small businesses for three natural hazard events occurred in Nepal, Puerto Rico and Mexico. A convenient and reliable method for nowcasting the post-emergency recovery status of economic activities could help local governments and decision makers to better target their interventions and distribute the available resources more effectively.

立即评估自然灾害事件（例如地震，洪水，飓风）对资产，人员和社会的影响的挑战对于评估此类系统从极端事件中恢复的能力至关重要。传统的恢复估算，例如调查和访谈，通常成本高昂，耗时且无法扩展。在这里，我们提出了一种方法，可以通过在社交媒体上在线发布活动来间接估计城市中小型企业的事后恢复状态（停机时间）。通过分析事件发生前后的发布时间序列，我们可以量化小型企业在尼泊尔，波多黎各和墨西哥发生的三个自然灾害事件的停机时间。