Where did the earthquake come from?
Japan is situated along the worlds most active earthquake belt, the Pacific Ring of Fire, where rigid plates in the earth's crust collide along the rim of the Pacific Ocean. This earthquake originated 231miles (373 kilometers) northeast of Tokyo and 80 miles (130 km) east o sendai, honshu in the PAcific Ocean. The earth quake ocured at a depth about 15.2 miles (24.4 kilometers).
In this area, the Pacific Plate, the plate beneath the Pacific Ocean, is moving almost due west and being pushed down into the Earth's interior along a trench off Japan's east coast. On average, the Pacific Plate is moving at 3.5 inches (8.9 centimeters) per year, but this process is not continuous, according to Keith Sverdrup, a professor of geophysics at the University of Wisconsin-Madison.
The process of one plate being pushed beneath another is called subduction, and it occurs all along the Ring of Fire, producing other earthquakes, including the 7.7 magnitude quake that struck off the coast of Indonesia in October.
What happened?
A reverse faulting had occurred where the Pacific Plate, 373 kilometres from Tokyo “dived” under the North American Plate.
Factors that contribute to the destructiveness of an earthquake:
1. Location - a populated area is more likely to do more damage.
2. Magnitude - the amount of seismic energy released.
3. Depth - deeper earthquake do less damage.
4. Distance from the epicentre - epicentre is the place where the earthquake originates.
5. Local geological conditions - nature of the ground (loose soils can liquefy).
6. Secondary effects - triggers tsunamis, fires, floods and landslides.
7. Architecture - poor construction obviously brings more damage.
