A huge, magnitude-8.7 earthquake shook Indonesia on 28 March, leaving 2,000 people feared dead on the island of Nias. But the event did not spark a tsunami like that of the 26 December earthquake, which occurred a little farther north.

Seismologists had recently concluded that the unruptured faults close to the 26 December epicentre, including the one that caused this earthquake, were close to failure (see pages 573–574). The latest event could verify such work. “This quake may be a vindication of the ‘stress transfer process’,” says Bill McGuire, an expert on earthquake hazards at University College London.

As Nature went to press, seismologists were still working out why the huge undersea earthquake, which apparently lasted some two minutes, did not set off a wave. The earthquake, among the eight largest on the planet since 1900, occurred in an area where lesser events have triggered killer waves before. One possibility is that the earthquake occurred deeper in the Earth than its December predecessor, and so did not shunt up the sea floor abruptly.

Thousands of people in Sumatra, Thailand and Malaysia fled the coasts as they felt the shaking on Monday, and governments issued a tsunami alert using radio and television broadcasts. The area is due to get a dedicated tsunami warning system by the end of this year, which should improve evacuation procedures and prevent false alarms.