Tsunami

On March 11, 2011, a massive 8.9 magnitude earthquake generated a wall of water that surged over the east coast of Japan, sweeping many to their deaths. Japan is situated along the active earthquake belt, the Pacific "Ring of Fire", where plates in the Earth's crust collide. The Pacific Plate is moving almost due west and being pushed down into the Earth's interior along a trench off Japan's east coast. The process of one plate being pushed beneath another is called subduction, producing other earthquakes.  This 8.9 is the largest Japanese quake on record and the fifth-largest quake worldwide since 1900, according to the U.S. Geological Survey (USGS). The earthquake caused the seafloor to suddenly shift vertically and this shifted the water column above it. This then spawned a series of massive waves known as a tsunami. The waves spread toward the east coast of Japan and toward the west, on a much longer path to the west coast of North America.

Earthquakes trigger tsunamis when the seismic activity causes the land along fault lines to move up or down. When parts of the seafloor shift vertically, either becoming raised or lowered, entire water columns become displaced.

Severe earthquakes in Haiti, Chile and now Japan have experts around the world asking whether the world's tectonic plates are becoming more active -and what could be causing it.

Some scientists theorize that the sudden melting of glaciers due to man-made climate change is lightening the load on the Earth's surface, allowing its mantle to rebound upwards and causing plates to become unstuck.

These scientists point to the historical increase in volcanic and earthquake activity that occurred about 12,000 years ago when the glaciers that covered most of Canada in an ice sheet several kilometres thick suddenly melted.

The result was that most of Canada's crust lifted -and is still rising.

Scientists have discovered that the accelerated melting of the Greenland ice sheet over the last 10 years already is lifting the southeastern part of that island several millimetres every year.

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http://www.livescience.com/13187-japan-earthquake-tsunami-science-faq.html
http://www.montrealgazette.com/technology/Scientists+link+melting+glaciers+earthquakes/4449816/story.html