美國次按風暴達到幾多級? 等唔等於香港ge10號風球?

They are 2 different things.

USA SUB-PRIME MORTGAGE means the lower credit ratings home owners made mortgage loans with the banks, but now, they might not be possible to repay their loans, hence, they will default and finally the whole US banking sector and US economy will be seriously deteriorated by this event

Typhoon is just natural diaster to HK.