Note: Map shows the area with a shake intensity of 4 or greater, which U.S.G.S. defines as “light,” though the earthquake may be felt outside the areas shown. The New York Times
A major, 7.4-magnitude earthquake struck off the northeast coast of Japan on Monday, according to the United States Geological Survey. The Japan Meteorological Agency reported the quake had a magnitude of 7.7.
The temblor, which could be felt several hundred miles away in Tokyo, happened at 4:53 p.m. Japan time about 62 miles northeast of Miyako, Japan, data from the U.S.G.S shows.
As seismologists review available data, they may revise the earthquake’s reported magnitude. Additional information collected about the earthquake may also prompt U.S.G.S. scientists to update the shake-severity map.
Aftershocks detected
Subsequent quakes have been reported in the same area. Such temblors are typically aftershocks caused by minor adjustments along the portion of a fault that slipped at the time of the initial earthquake.
Quakes and aftershocks within 100 miles
Aftershocks can occur days, weeks or even years after the first earthquake. These events can be of equal or larger magnitude to the initial earthquake, and they can continue to affect already damaged locations.
When quakes and aftershocks occurred
Source: United States Geological Survey | Notes: Shaking categories are based on the Modified Mercalli Intensity scale. When aftershock data is available, the corresponding maps and charts include earthquakes within 100 miles and seven days of the initial quake. All times above are Japan time. Shake data is as of Monday, April 20 at 5:11 p.m. Japan time. Aftershocks data is as of Tuesday, April 21 at 1:23 a.m. Japan time.
