"Shaking in 5 Seconds!"—Performance and User Appreciation Assessment of the Earthquake Network Smartphone-Based Public Earthquake Early Warning System

Public earthquake early warning systems have the potential to reduce individual risk by
warning people of approaching tremors, but their development has been hampered by
costly infrastructure. Furthermore, both users’ understanding of such a service and their
reactions to actual warnings have been the topic of only a few surveys. The smartphone
app of the Earthquake Network initiative utilizes users’smartphones asmotion detectors
and provides the first example of a purely smartphone-based earthquake early warning
system, without the need for dedicated seismic station infrastructure and operating in
multiple countries. We demonstrate that this system has issued early warnings in multiple
countries, including for damaging shaking levels, and hence that this offers an alternative
to conventional early warning systems in the foreseeable future. We also show
that although warnings are understood and appreciated by users, notably to get psychologically
prepared, only a fraction take protective actions such as “drop, cover, and hold.”