Reasoning for consistent Earthquakes

The quantity of earthquakes that Japan experiences is due to the location of the islands. Japan sits on multiple continental and oceanic plates. The number of plates also contribute to the large amount of volcanoes and hot springs on the islands. If the earthquakes occur near the ocean there is then the possibility of a subsequent tsunami, which was the case on March 11, 2011.


Historical Earthquakes: 

• The Great Kanto Earthquake in 1923: hit both Kanto and Tokyo, resulted in over 100, 000 deaths

• Southern Hyogo Earthquake or Great Hanshin Earthquake in 1995 an eathquake hit and killed 6,000 people while injuring another 415,000.  

Northern Japan sits right on the tip of the west edge of the North American plate. The area where the North American Plate and the Pacific plate meet is called the Japan Trench. The Earthquake on March 11th was a result of the Pacific Plat faulting underneath the North American Plate. The push of the North American plate upwards created a huge amount of energy and water to be forces upwards, creating the tsunami. The energy from this radiates and sends waves traveling at high speed.The collision occurred 17 miles below the earth's surface.
This link gives a very clear overview, step by step as to what caused the earthquake and tsunami. 

The Ring of Fire: 
 The ring of fire is located around the pacific basin in a 40 000km semicircle. The ring of fire consists of 452 volcanoes, which is about 75% of the world's both active and dormant volcanoes. Close to 90% of the world's earthquakes occur in the ring of fire as a result of the high number of continental and oceanic plates. The consistent volcanic and earthquake action was noticed even before the plate tectonic theory was accepted. The Ring of fire is referred to as a subduction zone. A huge amount of energy is created by the movement of the plates, which explains the amount of volcanoes in the area. 
An article from about.com clearly explains each plate and its responsibility. 

"This is a listing of major volcanic areas in the Ring of Fire:

• In South America the Nazca plate is colliding with the South American plate. This has created the Andes and volcanoes such as Cotopaxi and Azul.
• In Central America, the tiny Cocos plate is crashing into the North American plate and is therefore responsible for the Mexican volcanoes of Popocatepetl and Paricutun (which rose up from a cornfield in 1943 and became a instant mountains).
• Between Northern California and British Columbia, the Pacific, Juan de Fuca, and Gorda plates have built the Cascades and the infamous Mount Saint Helens, which erupted in 1980.
• Alaska's Aleutian Islands are growing as the Pacific plate hits the North American plate. The deep Aleutian Trench has been created at the subduction zone with a maximum depth of 25,194 feet (7679 meters).
• From Russia's Kamchatka Peninsula to Japan, the subduction of the Pacific plate under the Eurasian plate is responsible for Japanese islands and volcanoes (such as Mt. Fuji).
• The final section of the Ring of Fire exists where the Indo-Australian plate subducts under the Pacific plate and has created volcanoes in the New Guinea and Micronesian areas. Near New Zealand, the Pacific Plate slides under the Indo-Australian plate."

The cause of the March 11th Earth quake:

 
Subduction: is the result of a more dense plate forcing another plate up by moving beneath it. 



















http://geography.about.com/cs/earthquakes/a/ringoffire.htm