Earthquake and tsunami in Honshu, Japan: 11th March 2011

Updated Wednesday, 11th March 2015
Shortly after news started to come through of the massive earthquake in Japan, David Rothery shared his thoughts for us.

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This morning's Japanese earthquake (11th March 2011 at 05:46 GMT) measured 8.9 on the Richter scale. That is very powerful, and in an average year there is only one quake more powerful than 8.0 anywhere in the globe.

At its source, it was over a thousand times more energetic than the magnitude 6.3 quake that struck Christchurch on 22 February.

USGS map showing the 11th March earthquake
USGS map showing the earthquake

This one occured about 25 km below the seabed, and the displacement of seawater caused a series of tsunami waves capable of causing far more damage than the on-land ground shaking.

Parts of the eastern coast of Japan have already been inundated, but there is a tsunami warning in force across most of the Pacific basin. For example,the first waves are expected to reach Hawaii 19 hours after the earthquake.

This earthquake was a consequence of the floor of the Pacific ocean being dragged under Japan as a result of plate tectonic movements.

It was preceded by a nearby magnitude 7.2 quake on 9 March and there was a magntiude 7.1 aftershock at 06.25 GMT.

The 2004 Boxing Day tsunami in the Indian ocean was caused by a magntide 9.1 earthquake where the floor of the Indian ocean is dragged below Sumatra.

Tokyo streets following the Honshu earthquake
The normally busy streets of Tokyo fall silent following this morning's earthquake. Photo by japan_style.

Find Out More

USGS report on the earthquake

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  • picture of David Rothery

    David Rothery

    (Department of Physical Sciences)

    Professor David Rothery is a volcanologist and planetary scientist at The Open University, where he is Professor of Planetary Geosciences within the Department of Physical Sciences. He chairs modules in level 2 planetary science, and ...

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