In Indonesia, the death toll from Monday's tsunami has risen to more than 400. Hopes are fading for more than 300 others still listed as missing after the huge wave, triggered by a powerful earthquake, struck the Mentawai islands off the west coast of Sumatra. The Indonesian officials have revealed significant holes in the tsunami warning system. After the tsunami killed more than 2,30,000 people around the Indian Ocean in 2004, a string of sensor buoys was distributed off the Indonesian coast. But the survivors said they had almost no warning that the three-metre wall of water was bearing down on them, despite the alarm buoys. Deputy Chairman of the agency responsible for managing the buoys Riduan Jamaluddin said most of the alarm buoys are not working. He said initial plans for 22 buoys were scaled down to 12. Jamaluddin revealed that only three or four have survived technical problems. An official tsunami warning was issued after Monday's 7.7-magnitude quake, but it either came too late or did not reach the communities in most danger.