Five strong earthquakes have shaken India in the last decade, and new evidence has convinced scientists that much worse appears not only inevitable, but overdue. An analysis of the shifting subcontinent found enormous pent-up strain along most of the 1,200-mile arc where it slides under the Himalayas and the Tibetan plateau beyond. Dr. Roger G. Bilham, a geologist at the University of Colorado is an author of the new study, which is described in the current issue of Science.