Berkeley professor Joshua Bloom is part of the beta-testing team for ShakeAlert, an earthquake early warning system. He has used a Raspberry Pi to tap into the data source of the system to provide him with a 5-second warning should a large earthquake occur. You can read more here. The data source is not currently available to the public, but it is hoped that the use of a low-cost board to demonstrate the feasibility of personal warning systems could be used to get the project funded fully.