Fast Facts about the Japan Earthquake and Tsunami

The speed of the Pacific Plate, the distance Japan's main island was displaced, and other facts and figures about the March 11 earthquake help to put this event into perspective

By Francie Diep

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Why was Japan's March 11 earthquake so big? One answer is the large size of the fault rupture as well as the speed at which the Pacific Plate is continuously thrusting beneath Japan, U.S. Geological Survey (U.S.G.S.) scientist Tom Brocher told KQED News. People felt shaking in cities all over Honshu, Japan's main island.

Below are some more facts and figures relating to the causes and consequences of the world's fifth-largest earthquake since 1900.
Magnitude, according to USGS: 9.0
Speed at which the Pacific Plate is smashing into the Japanese island arc: 8.9 centimeters (3.5 inches) per year

Speed at which the San Andreas Fault in California is slipping: about 4 centimeters per year

Size of the rupture along the boundary between the Pacific and North American plates: 290 kilometers (180 miles) long, 80 kilometers across

Approximate length of Honshu island: 1,300 kilometers

Years since an earthquake of this magnitude has hit the plate boundary of Japan: 1,200

Duration of strong shaking reported from Japan: three to five minutes

Greatest distance from epicenter that visitors to the USGS Web site reported feeling the quake: About 2,000 kilometers

Distance that the island of Honshu appears to have moved after the quake: 2.4 meters

Change in length of a day caused by the earthquake's redistribution of Earth's mass: 1.8 microseconds shorter

Normal seasonal variation in a day's length: 1,000 microseconds

Depth of the quake: 24.4 kilometers

Range of depths at which earthquakes occur in Earth's crust: 0 – 700 kilometers

Top speed of a tsunami over the open ocean: About 800 kilometers per hour

Normal cruising speed of a jetliner: 800 kilometers per hour

Length of warning time Sendai residents had before tsunami hit: eight to 10 minutes

Number of confirmed foreshocks to the main shock: four

Magnitudes of the confirmed foreshocks: 6.0, 6.1, 6.1 and 7.2

Number of confirmed aftershocks: 401

Worldwide average annual number of earthquakes over magnitude 6.0: 150

Additional sources: USGS, CNN, SPACE.com, National Oceanic and Atmospheric Administration, Boeing, PBS NewsHour

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