An earthquake has rattled the Tokyo area hours after a stronger tremor caused a small tsunami on the northern Japanese coast. The Japan Meteorological Agency said the second earthquake was magnitude 6.1, and took place just off the coast of Chiba, east of Tokyo, at a rather shallow 6 miles below the sea surface. There was no immediate report of damage or injury from the second quake. The 6.8-magnitude tremor earlier last night caused a small swelling of water on the northern coast, including part of the region hit by last year's massive earthquake and tsunami. (More Japan earthquake stories.)