USGS COMMUNITY INTENSITY MAP: This map shows the intensity of shaking and damage at 14:46 local time near the east coast of Honshu, Japan's main island, on March 11, 2011. Indigo-blue represents weak to light shaking and no damage. Red represents violent to extreme movement with heavy to very heavy damage. Oranges represent very strong to severe shaking causing moderate damage.
Image: USGS
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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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Add CommentApparently, Japan moved 8 inches closer to the US due to the earthquake. That is in less than a week!
Reply | Report Abuse | Link to thisThis is the best information I have found. Thank you. I have now learned that the eepicenter was 80 miles from Sendai. I assume that is where the fault is. My friends and I are wondering how far the San Andreas fault and the faults in NY and Ilinois are from nuclear power plants and major cities. Although I did not articulate this well, perhaps you can address our concern about US vulnerability.
Reply | Report Abuse | Link to thisthanks that help a lt for my SOSE assignment
Reply | Report Abuse | Link to thisthat helps a lot thankyou
Reply | Report Abuse | Link to thisthanks for the information, it really helps a lot with studying this as my case study for my leaving cert
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