All across northern Japan, they felt it—a violent, magnitude 9.0 earthquake on March 11, 2011.
It was centered about 80 miles offshore, and tsunami warnings went up immediately.
In coastal cities, people knew what to do next: run to higher ground.
It's from these vantage points on hills and in tall buildings that incredible footage was captured.
In Kesennuma, people retreated to a high-rise rooftop and could only watch in horror as tsunami waves inundated their city, knocking buildings into rubble and mixing into a kind of tsunami soup filled with vehicles, building parts, and contents.
Seawater cascaded over seawalls and into cities.
This video shows the water rushing over an 18-foot seawall in the Kamaishi city.
The seawall here was the world's deepest and largest, but not enough for the magnitude of the March 11 disaster.
It was the largest quake ever known in Japan, and one of the five largest recorded in the world.
More than 28,000 people are confirmed dead or missing.
When two tectonic plates push together under the sea, the resulting earthquake sends an enormous burst of energy up through the ocean, displacing enormous quantities of water.
With the upward motion, a series of waves expands in all directions.
In deep water, these waves travel fast—up to 500 miles an hour—but only reach a height of a few feet.
A passing ship might not even notice.
But as the waves enter shallow waters, friction with the ocean floor lowers the waves' speed, but raises their height.
This video is from a Japan coast guard ship confronting a tsunami wave in shallow water on March 11.
And a rare view from the air—video of a tsunami wave approaching the shoreline.
In Japan, some tsunami waves reached as far as three miles inland.
Japan may be the most seismologically-studied country in the world, and with more than 1,200 high-precision GPS stations, a geophysicist at the University of Alaska used the data to create a visualization of the March 11 quake.
The waves of displacement that you see were moving as fast as five miles per second.
In this photo, the ripples of tsunami waves are seen moving upstream in the Naka River at Hitachinaka City.
New technology left an enormous amount of visual evidence for study in years to come, and can, perhaps, help us better understand the power of earthquakes and tsunamis, and prevent loss of life in the future.
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