Magnitude 6.1 quake off Tokyo triggers alert despite no tsunami warning.
Context
What happened: A magnitude 6.1 earthquake struck offshore in the sea near Japan's Kanto region, the Japan Meteorological Agency said.
Key numbers: Magnitude 6.1; quake hit at 7:39 pm; no tsunami alert issued.
Why it matters: The agency reported the quake was shallow and did not issue a tsunami alert.