The preferred origin, kept intact
The linked USGS record identifies the event as official20110311054624120_30. Its preferred origin is 38.297° north, 142.373° east, 29 kilometres deep, at 05:46:24 UTC on 11 March 2011. The preferred magnitude is 9.1 mww and the origin record is marked reviewed. The provider ID remains the event identity used by this page.
Provider revisions matter. A magnitude, depth, place label, or product status may change as observations are reviewed, so every value here is tied to the cited USGS page and the date on which this editorial snapshot was verified. The page does not combine alternate provider solutions into a fabricated average.
Magnitude is not a universal impact score
Magnitude describes earthquake size on a logarithmic scale. It does not by itself encode local shaking, building performance, exposure, tsunami effects, landslides, response capacity, or casualties. That is why the historical chart labels the exact source field and is paired with depth, time, location, and source status rather than presenting one dramatic ranking.
The comparison set is deliberately small and editorially selected. It includes the 1960 Great Chilean, 2004 Sumatra–Andaman, 2010 Maule, and 2011 Tohoku source records. It is not a complete ranking of earthquakes and must not be expanded automatically into thousands of event URLs.
Historical context is not a current warning
Nothing on this page asserts current calm or current danger near Japan. The interactive coordinate view has no real-time data and no hazard layers. For a current earthquake, aftershock, tsunami, evacuation, or infrastructure question, readers must follow the competent national and local authorities and current USGS products.