Global positioning systems (GPS) could provide faster tsunami alerts than current warning set-ups, German researchers said Wednesday, citing data collected in last year's deadly Japan earthquake.

"On the occasion of the Fukushima earthquake, we analysed data from more than 500 GPS stations and showed that a correct estimate of the magnitude of 9.0 and of the generated tsunami could have been possible in just three to four minutes after the earthquake," Andrey Babeyko, a scientist from the German Research Centre for Geosciences (GFZ) in Potsdam, said in a statement.

This "shows again what potential a GPS shield has in tsunami early warning systems," he added.

The findings were presented at a week-long conference of the European Geosciences Union in Vienna.

If an earthquake occurs near the coast, it can take just 20-30 minutes before a resulting tsunami hits land, but GPS measurements taken almost while the earthquake is still happening would enable a faster assessment of its scale, the researchers said.

Traditional measuring methods require more time to provide an accurate picture, often underestimating the magnitude of a quake at first, they added.

In the case of last year's earthquake in Japan, the authorities became aware of its scale only 20 minutes after the event, possibly leading to many more casualties than if a warning had gone out earlier, according to GFZ.

Some 19,000 people died when a 9.0-magnitude earthquake off the northeastern coast of Japan on March 11, 2011 triggered a tsunami and a meltdown at the Fukushima nuclear plant.