hey goldmining,
just look at the time and sequence of the trades after you have someone sell into the ask without a limit to the sale. As it runs down and cleans out the asks other houses start to sell in time with the original sale. This is a sign of stops being triggered.
You don't know for fact that it is a stop loss trigger but it is a reasonable guess. Most retail traders (me included) are to rattled by a flash crash to react quickly and their natural tendency is towards hope! Stupidly though! Hope isn't a business strategy. But, what does happen is that traders don't sell that quickly unless they are pro's, highly disciplined or electronic stop losses.
Usually it is the latter......especially when dealing with penny stocks on the Venture!
hope this helps..........carry