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Historical event archive

Japan earthquake and tsunami of 11 March 2011

A structured guide to reporting on the Tōhoku earthquake, its tsunami, major aftershocks, humanitarian response, damage assessments and long-term aftermath.

Date11 March 2011
RegionOff northeast Honshu
EventMegathrust earthquake
This archive discusses a disaster with extensive loss of life and displacement. Historical figures changed as authorities reconciled records; linked reports reflect the information available at publication.
Archive overview

What happened

On 11 March 2011, a very large undersea earthquake occurred off the Pacific coast of northeast Japan. The rupture generated a destructive tsunami that affected communities across the Tōhoku region and caused a wider emergency that included severe infrastructure disruption and the Fukushima Daiichi nuclear accident.

This page organizes the site’s contemporaneous reports and later follow-ups. Early entries contain preliminary earthquake parameters and impact estimates that were subsequently revised. They should be read as a record of evolving information rather than a final official account.

Chronological index

Reports and follow-ups

The newest archive items appear first. Titles have been calmly edited for clarity; linked pages retain their original URL structure.

2012 follow-up

Anniversary reviews and observations of debris movement across the Pacific.

April 2011

Aftershocks, field surveys, damage reporting and the transition toward longer-term recovery.

March 2011

Initial reporting, the evolving seismic sequence, impact estimates and emergency response.

Earlier background

Context published before the 11 March event.

Related archive paths

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Archive method

How we present this event

Earthquake Report separates historical reporting from present-day guidance and makes uncertainty visible.

  1. Preserve chronology. Entries remain ordered so readers can follow how information developed.
  2. Clarify preliminary data. Early magnitude and impact figures are identified as estimates where relevant.
  3. Use measured language. Distressing events are summarized factually without graphic detail.
  4. Point to preparedness. Historical lessons connect to practical earthquake and tsunami guidance.
Common questions

2011 Tōhoku archive FAQ

Why do early reports show different magnitudes?

Rapid estimates were calculated from limited incoming station data. Seismic agencies refined the earthquake’s size, location and rupture characteristics as more observations became available.

Are the impact totals on old pages final?

No. Early casualty, building and economic estimates changed as records were reconciled and assessments expanded. Each figure should be read in its publication context.

Was the tsunami caused by an aftershock?

The destructive tsunami was generated by the main megathrust earthquake on 11 March. Contemporary terminology in some early pages was inconsistent while the sequence was still developing.

Why are some archive titles edited here?

Index titles have been shortened or paraphrased for clarity, accuracy and respectful presentation. The established destination URLs remain unchanged.

Does this page provide current warnings?

No. It is a historical archive. For an active earthquake or tsunami threat, follow local emergency authorities and official warning centers immediately.

What should coastal residents do after strong shaking?

Follow local evacuation guidance. Long or strong coastal shaking can be a natural tsunami warning, so move promptly toward designated safer ground rather than waiting near the shore.