1 big one and at least >200 aftershocks
As of Oct 2011 there were 17 earthquakes of magnitude 7.0 and greater in 2011 with the largest being magnitude 9.0 in Japan on March 11th. The list of earthquakes by year (1990-Present) or by country can be found at the USGS Earthquake Hazards website. It provides a list of significant earthquakes for 2011 as well as a worldwide map of earthquakes for 2011. See link below maps, lists, and statistics.
There were 468 earthquakes with magnitude 5.0 - 5.9 (of that 141 were M 5) between March 12 and July 6th of 2011 according to the USGS earthquake data.As of July 6 there were 4,143 earthquakes in Japan region for year 2011 (not including small quakes under M 3.0) with March the most active month of the year.
On March 11, 2011 alone, there were 200+ aftershocks. From the 9.0 magnitude earthquake on Friday March 11 05:46:23 UTC until March 31 midnight there were approximately 2,806 earthquakes ranging in magnitude 3.9 through 7.9. As of August 10 there were 4,308 earthquakes in or near Japan for year 2011 according to the USGS earthquake data (not including small quakes under M 3.0) with March the most active month of the year. That's on average over earthquakes 19 per day.
One 8.9 Magnitude and about 100 6.0 Aftershocks
On Thursday March 10, 2011 a series of aftershocks rattled Japan (including a magnitude 6.6 quake) after the magnitude 7.3 quake hit the northeastern Honshu island March 9, said the Japan Meteorological Agency. On March 11, 2011 alone, there were 200+ aftershocks. From the 9.0 magnitude earthquake on Friday March 11 05:46:23 UTC until March 31 midnight there were approximately 2,806 earthquakes ranging in magnitude 3.9 through 7.9. As of August 10 there were 4,308 earthquakes in or near Japan for year 2011 according to the USGS earthquake data (not including small quakes under M 3.0) with March the most active month of the year. That's on average over earthquakes 19 per day.
No. It is only one of many times that an earthquake and tsunami have hit Japan. Earthquakes in subduction zones such as the one of the coast of Japan often trigger tsunamis. The March 2011 earthquake, at magnitude 9.0, was the strongest on record in Japan though.
about 16,000
Because the island of Japan lies in an area where several plates meet, it has experienced frequent earthquakes. Earthquakes are caused by the release of energy or seismic waves when these plates move. See the related links below for a list of earthquakes that have hit Japan in the past. The most recent earthquake and biggest to ever hit Japan occured March 11, 2011 and measured 8.9 on the Richter scale.
Yes and no. There have been many after shocks and earthquakes after March 11. On March 28 7:37 AM Japan local time (March 27 8:37 PM Eastern time) there was another earthquake near Miyagi prefecture, Magnittude 6.5 or (5 weak) on the Japanese scale was recorded in Ishinomaki city/ Miyagi prefecture.
japan
There were a number of earthquakes in Japan in 2012 ranging in magnitudes up to 7.3, but no deaths were reported. World-wide a total of 768 deaths from earthquakes in 2012 were recorded by the USGS Earthquake National Center and none of those from Japan. The last major earthquake from Japan was the magnitude 9.0 quake on March 11, 2011 that killed over 15,000 people in junction with the tsunami that it triggered.
One 9.0Near the East Coast of Honshu, Japan 2011/03/11 05:46:23