Apparently, there have been no official announcements, at least three submarines (American, Chinese and Indian), detected the December 26th underwater earthquake that caused the tidal waves that left over 150,000 dead along the shores of the Indian ocean. Modern submarines carry sensitive sensors used to detect other subs, and surface ships. These sensors also pick up the sounds of underwater creatures, as well as underwater volcanoes and earthquakes. A Cold War system of fixed sensors in the Pacific also picks up natural underwater events, and led to the current early warning system there for events like the December 26th catastrophe. The American and Indian subs are said to have returned to base, but not the Chinese sub. If the subs were close enough to the quake, they could have been damage by the underwater shock waves that caused the tidal waves. Chinese subs are more likely to suffer damage from poorly trained crews, than from underwater earthquakes.