Minor tsunami hits Japan after undersea quake

A strong undersea earthquake unleashed a small tsunami Feb. 17 off the same coastline of northern Japan devastated by a tsunami in 2011 that left more than 18,000 people dead.
      
The quake was followed by a series of tremors, the largest of which was magnitude 5.8, but there were no immediate reports of damage or casualties.
      
A wave of 20 centimetres (eight inches) was recorded off the city of Kuji at 9:07 am (0007 GMT), way below the possible one metre (3.3 feet) tsunami that the Japan Meteorological Agency (JMA) warned could hit.
      
Waves of up to 10 centimetres were recorded along other parts of the coastline of Iwate prefecture.
      
Aerial footage showed no perceptible rise in sea levels along the coast. There was no visible change at the ports in the area, where broadcaster NHK has cameras permanently stationed.
      
The JMA said the 6.9 magnitude tremor struck at 8:06 am in the Pacific some 210 kilometres (130 miles) east of Miyako, at a depth of 10 kilometres.
      
An official told a Tokyo news conference that geologists regard the quake as an aftershock of the 2011 earthquake.
      
The US Geological Survey put the magnitude at 6.7.
      
Another quake measuring magnitude 5.8 struck in the Pacific off Iwate Tuesday afternoon, the USGS said. No tsunami warning was raised.
      
As soon as the morning quake hit, Japan's well-tested system of public alerts sprang into action, with NHK giving blanket coverage.
      
Announcers urged viewers to seek safety on higher ground and warned against going to the shore to watch for possible effects.
      
Public address systems all along the coast also broadcast warnings, while emergency vehicles...