I have been quite interested in using a mesh network in conjunction with on-device accelerometers to give an early warning earthquake alert. The algorithms do exist (http://news.berkeley.edu/2016/02/12/new-app-turns-smartphones-into-worldwide-seismic-network/). As on-device sensor fusion becomes more pervasive thanks in part to things like Google's TensorFlow Lite, we should be able to make this a reality.

Also related, check out this video here. At the 35 second mark, you can see a quick glimpse of a hackathon project that one of our devs made last year. In this, sensor data from an Arduino processor was used to trigger an alert out across the mesh. https://www.youtube.com/watch?v=ELfJh8Yrqwg ... This one was for heat (fire alarm), but the concept remains similar to your idea.