An explosion shattered a building housing a nuclear reactor today amid fears of a meltdown, while across wide swaths of north-eastern Japan officials searched for thousands of people missing more than a day after a devastating earthquake and tsunami.

Another powerful earthquake has hit the same area where a nuclear power plant has already leaked some radiation.

Miles from the ocean’s edge, weary, mud-spattered survivors wandered streets strewn with fallen trees, crumpled cars, even small airplanes.