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Government or official record

M 9.1 — 2011 Great Tohoku Earthquake, Japan

U.S. Geological Survey

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Where this source supports the record

Each entry separates the File’s editorial relevance note from its exact, section-level claims. A bibliography link without a direct claim is labeled plainly.

  1. Natural disasters · 11 March 2011

    The 2011 Tōhoku Earthquake and Tsunami

    Pacific coast of Tōhoku, northeastern Honshu · Japan

    Open File evidence →
    Why editors use it here

    Authoritative event record for magnitude, epicenter, rupture, shaking, and the earthquake's regional setting.

    1. Quick read

      A magnitude 9.1 megathrust earthquake off northeastern Honshu generated a tsunami that reached the coast within about 30 minutes.

      Reviewed 24 July 2026
    2. Trigger and conditions

      A huge area of the plate boundary east of Honshu ruptured, displacing the seafloor.

      Reviewed 24 July 2026
    3. Uncertainty

      Official casualty totals change as missing-person cases are resolved and agencies use different reporting dates.

      Reviewed 24 July 2026
    4. Why it matters

      Tōhoku shows both the life-saving value and the limits of preparedness.

      Reviewed 24 July 2026