2011 Tōhoku Earthquake & Tsunami (M9.1): Japan's Fukushima Disaster

On 11 March 2011, a magnitude 9.1 megathrust earthquake struck off the Pacific coast of the Tōhoku region of northeastern Japan. It was the most powerful earthquake ever recorded in Japan and one of the five strongest ever measured worldwide. The rupture, along the boundary where the Pacific Plate subducts beneath the plate carrying Honshu, lasted several minutes and shifted the coastline eastward by metres.

Powerful ocean wave — the kind of tsunami that struck Japan's Tōhoku coast in 2011

The earthquake generated a devastating tsunami with waves that reached heights of up to about 40 metres in some inlets and surged several kilometres inland across the low-lying Sendai plain. The vast majority of the roughly 18,000 to 19,500 deaths and missing were caused by the tsunami rather than by the shaking itself. Entire towns along the coast were swept away within minutes of the waves arriving.

Aerial view of a Japanese coastal town, the kind of low-lying area devastated by the 2011 tsunami

The tsunami crippled the Fukushima Daiichi nuclear power plant, knocking out cooling systems and triggering meltdowns in three reactors — the worst nuclear accident since Chernobyl. Hundreds of thousands of residents were evacuated from the surrounding exclusion zone, some permanently. The disaster reshaped Japanese energy policy and prompted major upgrades to tsunami defences and early-warning systems.

Nuclear power plant cooling towers, similar to the Fukushima Daiichi plant crippled by the 2011 tsunami

At an estimated $360 billion in damage, the Tōhoku earthquake remains the costliest natural disaster in recorded history. Japan's dense network of seismometers gave residents up to a minute's warning via the Earthquake Early Warning system before the worst shaking arrived, and the event pushed the country to raise tsunami sea walls and revise evacuation planning nationwide. More than a decade later, the Fukushima Daiichi clean-up and decommissioning is still ongoing and is expected to take decades more.

NOAA's National Centers for Environmental Information (NCEI) catalogues the Tōhoku tsunami as one of the best-instrumented events in its global historical tsunami database, with field surveys confirming runup heights over 40 metres at Miyako Bay — among the highest ever measured worldwide. NCEI's Significant Earthquake Database credits the March 2011 rupture with roughly 600 times the energy release of the 1995 Kobe earthquake, and its network of DART deep-ocean buoys tracked the resulting tsunami crossing the entire Pacific, triggering evacuations as far away as Chile, Hawaii and California hours after the quake.

Frequently asked questions

What caused the 2011 Tōhoku earthquake and tsunami?

A magnitude 9.1 megathrust rupture along the subduction boundary where the Pacific Plate dives beneath the plate carrying Honshu, off Japan's northeastern coast, displaced the seafloor and generated a tsunami with waves up to 40 metres high.

How many people died in the Tōhoku earthquake and tsunami?

Around 18,000 to 19,500 people were killed or went missing. The vast majority of deaths were caused by the tsunami rather than by the earthquake's shaking itself.

What happened at the Fukushima Daiichi nuclear plant?

The tsunami knocked out backup generators and cooling systems, causing meltdowns in three reactors — the worst nuclear accident since Chernobyl — and forcing the evacuation of hundreds of thousands of residents from the surrounding area.

How tall was the Tōhoku tsunami?

Wave heights reached roughly 40 metres in some narrow inlets such as Miyako Bay, among the tallest tsunami runups ever measured, though most of the affected coastline saw waves in the 10–15 metre range.

Was the Tōhoku earthquake predicted or given warning?

The earthquake itself was not predicted, but Japan's dense seismic network gave residents up to about a minute's warning through the Earthquake Early Warning system before the strongest shaking arrived.

How much did the Tōhoku disaster cost?

Estimated damage reached about $360 billion, making it the costliest natural disaster in recorded history — far above Hurricane Katrina or the 1995 Kobe earthquake.

Is the Fukushima Daiichi clean-up finished?

No. More than a decade later, decommissioning of the plant and removal of melted nuclear fuel is still ongoing and is expected to take decades more to complete.

How does Tōhoku compare to the biggest earthquakes ever recorded?

At M9.1, Tōhoku ties with the 2004 Sumatra earthquake for fourth place among the largest earthquakes ever measured, behind only Valdivia 1960 (M9.5) and Alaska 1964 (M9.2).