In relation to the Sumatran Quake it is interesting to note its proximity to huge underwater gas hydrate deposits which could contain Methane Hydrate.

57% of the world's 600 active volcanoes form islands or occupy coastal sites, while 38% are located within 250 kilometers of the coast. They could all be susceptible to the changes in the stress on the crust that will come with the rising sea-level if runaway thawing of the polar ice sheets really begins. This will lead to an increase in continental margin earthquakes, which are more likely to trigger sea-floor landslides. These sea-floor landslides are the very thing that could trigger the release of Methane Hydrate. Gas hydrates have been identified around the margins of all the ocean basins.