Earthquake

It may make sense to combine high and low tech warning systems, once an earthquake is detected. In Padang it was reported that communications were DOWN after the earthquake struck. The size of Summatra/ Indonesia earthquake, makes a complete warning system unlikely.

All to often, buildings are poorly constructed, collapsing like a pack of cards, upon those inside. In recent earthquakes with high casualty numbers, it is the design and construction of multi-storied buildings, that are THE problem. Enforcing laws on building safety is the key to prevention, but nations where corruption is endemic, will prevent safe buildings, as they cost considerably more, and it may be cheaper to bribe, although more expensive to rebuild after collapse.

In China's recent quake, citizens turned their anger towards government officials, as schools etc collapsed even as SOME newly constructed private buildings remained undamaged.
There are many countries across all continents where poorly constructed buildings are a danger to those inside, should a quake occur.

Human greed appears to sit at the heart of most problems, and sadly such incidents will reoccur