Scenes from the M8.9 Earthquake in Japan
An 8.9-magnitude earthquake hit off the east coast of Japan early today. The quake -- one of the largest in recorded history -- triggered a 23-foot tsunami that battered Japan's coast, killing hundreds and sweeping away cars, homes, buildings, and boats.
The US-run Pacific Tsunami Warning Center said amplitudes (top to bottom of waves) of up 7.3m were recorded on the coast of Japan.Japan's Kyodo news agency reported that a 10m wave (33ft) struck the port of Sendai, carrying ships, vehicles and other debris inland.Even out in the deep ocean, the specialist tsunami warning buoys were recording wave amplitudes of a metre, which is considerable.This means waves will have reached out across the Pacific, towards the Philippines, Hawaii and perhaps even to be recorded on the landmasses of North and South America.What is likely to interest seismologists will be the association with a number of very strong foreshocks in recent days.
These began on 9 March with a Magnitude 7.2 event just 40km from Friday's earthquake, and continued with a further three earthquakes greater than Magnitude 6.0 on the same day.In terms of public awareness and reaction, these foreshocks could turn out to be quite important because they will have reminded people what they are supposed to do in a big quake to protect themselves.
Remember, the scale used to measure earthquakes is not a simple linear one.Each step in magnitude equates to a 32 times jump in the release of energy. As a consequence, Friday's 8.9 event was some 250 times more energetic than anything seen on Wednesday this week; and about 1,400 times more energetic than the Great Hanshin, or Kobe, earthquake in 1995 (M 6.8).
Japan has had about 10 quakes since 1900 that have resulted in major casualties, typically a few thousand people each time."The exception is the 1923 Great Kanto earthquake, Tokyo, which killed 140,000," Dr Elliot said."The 1995 Kobe earthquake in southern Japan had about 6,500 deaths, but was different in that it was not a subduction event, and was located under a populated area."
