As the world comes to terms with the tragedy of Haiti, we hear a grim warning that Indonesia faces another mega-earthquake and a possible tsunami, which could be as severe as the Boxing Day 2004 event which killed an estimated 230,000 people around the Indian Ocean.
John McCloskey of the University of Ulster, an authority on Indonesian earthquakes, issues the warning in the journal Nature Geoscience. He focuses on a section of the notoriously active Sunda zone west of Sumatra, where the Australian tectonic plate runs under the Eurasian plate.
There have been three huge earthquakes along this plate boundary in 2004, 2005 and 2007. But the full strain remains in one section, the 300km Mentawi segment opposite the city of Padang. A substantial magnitude 7.6 quake here last September killed 1,000 people, but unfortunately the analysis by McCloskey and colleagues shows that this did not relax 200 years of accumulated stress – and may have made a gigantic tremor in the near future even more likely.
“For hundreds of years the energy is stored as the two tectonic plates bend and deform. Then, in just a few seconds all this energy is released generating a massive earthquake and sometimes flexing the seafloor to create a tsunami,” McCloskey says. “Off western Sumatra the bow is drawn tight. The last shock happened more than 200 years ago and the stresses are probably larger now than they were then; the earthquake must happen soon.”
The quake will be at least magnitude 8.5 (far greater than Haiti’s 7.3) and it could unleash a tsunami even more destructive than in 2004.
Such an event would kill many thousands locally in Sumatra, though the Indian Ocean tsunami warning system set up since 2004 should prevent more widespread loss of life this time. Indonesia’s recent seismic history should also mean that it is somewhat better prepared for catastrophe than Haiti was – though again the international community will have to move quickly to help if (or when) the worst happens to Padang.