Japan tsunami live updates: At least 23 people injured after rare 7.5-magnitude earthquake strikes
Why Japan issues ‘megaquake’ advisories after significant earthquakes
- A powerful 7.5-magnitude earthquake struck off the coast of northeastern Japan late Monday, prompting tsunami warnings and evacuation orders for approximately 90,000 residents.
- The Japan Meteorological Agency initially warned of tsunamis up to 3 meters (10 feet) high, but hours later downgraded the warnings to advisories after observed waves reached 20-70 cm (7 to 27 inches).
- Japan is highly prone to earthquakes, experiencing a tremor every five minutes and accounting for 20% of global quakes over magnitude 6.0 due to its location in the Pacific “Ring of Fire.”
- One of the country’s most-deadly earthquakes, a 9.0-magnitude, struck in March 2011 and triggered a series of massive tsunamis two days after a magnitude 7-level quake.
- That tragedy claimed nearly 20,000 lives and led Japan to implement a one-week “megaquake” advisory system after significant earthquakes in a region, a system that was most recently activated in August last year for the Nankai Trough area in central-southern Japan.