GPS solution provides three-minute tsunami alerts

Researchers have shown that, by using global positioning systems (GPS) to measure ground deformation caused by a large underwater earthquake, they can provide accurate warning of the resulting tsunami in just a few minutes after the earthquake onset. For the devastating Japan 2011 event the analysis of the GPS data and issue of a detailed tsunami alert would have taken no more than three minutes.
Source: http://www.sciencedaily.com/releases/2013/05/130517085819.htm