The risk of a second massive tsunami in the Indian Ocean has increased as a result of last December's devastating events that killed at least 300,000. Seismic stress has been transferred to a nearby undersea geological fault making a follow-on quake much more likely.
University of Ulster scientist John McCloskey and colleagues publish their concerns this morning in the journal Nature.
They argue that a second massive quake is now more likely making the need for a tsunami warning system in the Indian Ocean "all the more urgent".
The "megathrust" earthquake off the Sumatran coast on December 26th last created a huge tsunami that radiated outwards, swamping coastlines in Thailand, Sri Lanka, India and other locations as far away as Africa.
Earthquakes are caused when the large slabs or "plates" that make up the earth's crust push or slide against one another. This seismic stress usually declines after a large earthquake, but quakes in regions similar to the Sumatran fault system are often linked.
Prof McCloskey points to similar paired quakes off Japan where five out of seven large events in the Nankai fault system were followed by nearby quakes within five years. Three of the quakes came within just 12 months of the original event.
These occur as a result of "stress interaction", Prof McCloskey reports. He also pointed out that both sections of the paired fault system off Sumatra were well overdue for large earthquakes.
The Sumatran quake last December was extremely large, measuring 9 on the open-ended Richter scale used for measuring the severity of these massive geological occurrences.
It ruptured almost 250,000sq km (150,000sq miles) of the fault where the Indian plate and the Burma microplate meet.
This movement has now increased stress along the Sunda trench that separates Indonesia from the Australian plate. It has also put more stress into the Sumatran fault near the city of Banda Aceh that suffered so badly in the last tsunami.
"Considering past activity and the observed structural complexity on the northern Sumatra fault, an earthquake of magnitude 7-7.5 on this structure would seem to represent the greatest immediate threat," Prof McCloskey and his colleagues report.