A 6.4-magnitude earthquake shook Japan's northern island Hokkaido Saturday, UPI quoted the officials as saying. There were no immediate reports of damage or casualties. The quake had a depth of about 75 miles and was centered about 68 miles west of the island's capital Kushiro, the Japanese Meteorological Agency reported, adding that the quake posed no tsunami risk. The U.S. Geological Survey reported the quake measured a 6.9 on the seismic scale.