Fukuoka was lucky - the quake on the 20th of March (6.6 Magnitude moment*, magnitude 7 on the local scale) killed 1 but was only a little smaller than the quake that lead to 6000 plus death in Kobe in 1995. Some reasons why: Duration: the actual slippage at the source lasted up to 1 second, leading to a tremor that lasted for around 30 seconds. Slippages lasting 1 to 2 seconds are more likely to produce severe damage. 2) The city sits on very strong bedrock. 3) The tremor occurred at 11am when most people were up and about and few people were cooking.

About the Kego fault ("Kego Danso")
The epicentre of the quake was at what is believed to be or related to the far end of the Kego Fault (Kego danso) around 30KM NW of Fukuoka. The fault runs through Daimyo and down through Yakuin to Ohashi. Occasional small tremors along it are not uncommon ( It runs under the go-fubar office - we speak from experience. Editor.) It had been assessed by the gov. as being 22km long, with an activity cycle of one M7 event every 15,500 years.

What the city had expected
For a magnitude 6.5 event in winter between 17:00 and 18:00 with 4km/sec of wind and an epicentre 10km deep, the tremor was EXPECTED to be felt at magnitude 4 to 6 in the city. It was assumed 2968 people would require evacuation with 77 dead, 2640 injured and 558 needing rescue. It was expected 952 wooden buildings and 103 non-wood buildings twould be destroyed with a further 3660 of both types badly damaged.

The last 7 magnitude quake in northern Kyushu was approximately 300 years ago.

Games to play during an aftershock.
Hi-Net, a government website displays preliminary assessments of earthquake magnitudes within about 45 seconds of a tremor hitting. Guess the size, loser does the washing up. This game keeps you focussed on the tremor and alert.

http://www.hinet.bosai.go.jp/
(Japanese, but with clear graphics.)


That earthquake pack...
Vital: Warm clothing and cheap plastic mac. Dried food, Water. Groundsheet. First aid kit for small cuts/abrasions. Work Gloves. Photocopy of passport and gaijin card, also details of your next of kin, etc. Medication you need. Useful: Toilet paper. Torch. Disposable mobile phone battery. Cheap radio. Spare batteries. Cash. Black plastic bags. Condoms. Soap. Contact lens cleaner/spare glasses. Portable stove.


Useful earthquake Japanese
danso - fault
jishin - earthquake
yoshin - aftershock
shingen - hypocentre (epi-centre)
ima no (jishin) wa tsuyokatta - oh shit, that was a big one.

Current US Gov assessment - the Japanese scales are slightly different. In general, a 5 mag earthquake will shake a building 10 times more than a 4 mag quake, but release 32 times more energy.


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