Meaning of “went through the floor”?

Question

Question:

I read this post:
http://answers.onstartups.com/questions/40480/how-much-traffic-is-necessary-to-generate-1000-per-month-in-advertising-revenue

Quote

I previously had a real estate listings site and was generating around $1500 mth with about 3000 unique users per day. Content was essentially syndicated but as Google changed algorithm the traffic went through the floor.

Now my question:
The expression "went through the floor", in this context, what does it mean, collapse or explode ?
I suppose collapse, since the floor is at the bottom, but with expressions, one never knows for certain...

Answer 1

Yes, it means to collapse, or go way down, or whatever. Contrast with "through the roof".

I can't find a reference but I'm pretty sure the expression originated in the financial markets, wherein a seller or regulator would set a price floor on a commodity or security, and if the value of said commodity fell below the floor, it was very undervalued and no one would buy it.

Answer 2

To go through the floor means "to fall to very low levels". So, your quote basically says that the traffic decreased dramatically.