A 7.2-magnitude quake struck on Monday off Indonesia's Sumatra island, sparking a tsunami alert, the geophysics and meteorology agency said. The quake hit 165km northwest of Sumatra's Mukomuko at 15:36 (08:36 GMT) at a depth of 10km, the agency said. The US Geological Survey put the magnitude of the quake at 7.1. The quake was felt in tall buildings in the capital Jakarta, where pictures swayed on walls.