A huge earthquake may be building beneath Bangladesh, which can turn urban areas in eastern India into “ruins”, a new study has warned. Scientists said they have new evidence of increasing strain where two tectonic plates underlie the world’s largest river delta. At least 140 million people in the region could be affected if the boundary ruptures; the destruction could come not only from the direct results of shaking, but changes in the courses of great rivers, and in the level of land already perilously close to sea level.