A powerful 8.6 magnitude earthquake and a series of strong aftershocks struck off Indonesia on Wednesday, sending people scurrying from buildings as far away as southern India, but there seemed little risk of a disastrous tsunami as in 2004. Indonesia said it was checking for damage and casualties but remarkably, no such reports had been received for several hours after the quakes, including in Aceh, the closest province and the area decimated by the disaster eight years ago.