question about BOJ intervention

[cantrell24x]

Guys

This will probably show my ignorance but I want to ask. If the average BOJ intervention is 4.5B maybe backed up a couple times after the initial, will that have a huge effect on the market? When so much is FOREX is traded everyday I wouldnt think 12B would make a huge difference. I guess I am wrong, with all the talk of intervention it must be a significant event. Would anyone mind explaining to me how such a small % of the daily amount traded will have a long term direction changing effect on the market

Thanks

Chris