A strong magnitude 6.9 earthquake struck off Indonesia on Sunday, the US Geological Survey reported, triggering a brief tsunami warning that sent panicked residents fleeing to higher ground. The Southeast Asian nation is one of the most disaster-hit on Earth due to its position straddling the so-called Pacific Ring of Fire, where tectonic plates collide. Earthquakes and tsunamis have claimed thousands of lives in recent years. Sunday's quake struck at a depth of 24 kilometres in the Molucca Sea, 185 kilometres southeast of Manado, between Sulawesi and Malkuku islands, according to the USGS.