Things radically changed with the smartphone revolution. Smartphones have everything needed to implement a low-cost monitoring network, and to join the network requires only a few clicks. If you are a seismologist, you would argue that smartphones are not secured to the ground (why would they be) and mainly record noise. True. Nonetheless, many smartphones connected to a network can offer reliable real-time detections and provide rapid preliminary estimates of the earthquake parameters.

All of this was first achieved in 2013 by the Earthquake Network (EQN) initiative (www.sismo.app), which implements a public smartphone-based earthquake early warning system. Citizens join the project by installing the EQN app. Through the same app, they receive early warnings a couple of seconds before the shakings occur at their location. The app immediately became popular in Central and South America, where people experience earthquakes every other day. Also, EQN was helpful to Nepalese citizens during the aftershocks of the April 2015 earthquake, which resulted in nearly 9,000 deaths. For a long time, EQN was simply recognised as a citizen science experiment. Only recently, it caught the attention of seismologists and turned into a research project.

Today, scientists of the EU-funded RISE and TURNkey projects are giving “seismological meaning” to the detections EQN has recorded throughout its history. Furthermore, they found that the network is indeed capable of sending early warnings for damaging shaking levels. For instance, the recent magnitude 7 earthquake on 8 September 2021, with its epicentre near Acapulco, Mexico, was detected after 5 seconds from origin time. The EQN app sent an early warning message about 10 seconds before the strong tremors occurred to people living in the nearest large city (Chilpancingo) and 55 seconds to people in Mexico City.

Whether citizens are aware or not, EQN is based on a strong solidarity principle. Smartphones detecting the earthquake are usually very close to the epicentre, where an early warning is not possible. If your smartphone is making a detection, the early warning will be useful for someone who lives a little further away from the epicentre, but not for you. However, you can expect the favour to be returned. Thanks to this spirit of collaboration, EQN has continuously grown, and new users worldwide join the network every day. Up to now, the app counts more than 8 million downloads and 1.5 million active participants globally, and EQN is for many countries the sole and only early warning system citizens can rely on.

While the number of smartphones in the network is increasing, new challenges need to be addressed. The EU-funded Horizon 2020 projects RISE and TURNkey are the perfect environment to study and implement new solutions, with EQN possibly interacting with classical monitoring networks to provide a more robust and faster early warning service across Europe and all over the world.

Read more about the EQN Project:

• Bossu, R., Finazzi, F., Steed, R., Fallou, L., Bondár, I. (2021) "'Shaking in 5 Seconds!' Performance and User Appreciation Assessment of the Earthquake Network Smartphone‐Based Public Earthquake Early Warning" System. Seismological Research Letters; https://doi.org/10.1785/0220210180

• Finazzi F. (2020) The Earthquake Network Project: A Platform for Earthquake Early Warning, Rapid Impact Assessment, and Search and Rescue. Front. Earth Sci. 8:243. doi: 10.3389/feart.2020.00243