The idea of using the sensors available in billions of smartphones for large-scale data gathering isn't new; but now we have one hoping to use it to detect earthquakes.
In the past we've seen projects wanting to use smartphones to gather temperatures for improved weather accuracy, and even to detect cosmic rays. Now, MyShake wants to use the same sensors it uses to detect when you're moving around to detect earthquakes.
We have to keep in mind the low-cost sensors used in smartphones can't compete with the scientific-grade sensors used in monitoring stations, but if you have a large enough number of them spread around a wide area, you can still get valuable data that can help detect impending earthquakes and give you a few seconds of head start to prepare for it.
There's one small detail though. Don't hope to detect an earthquake while you're moving around. The app requires you to leave you smartphone on a table; but on the other hand, it does all it work locally, not using up data nor having a noticeable impact on the battery life. Should you happen to detect an earthquake, the app will cache the relevant data, and send it to the researchers only when you connect to a WiFi network.
[MyShake for Android]