The chain of reasons starts with gold.
If I would take an educated guess, I'd say that some gold owners on the futures market finally started to dump their positions:
http://finviz.com/futures_charts.ashx?t=GC&p=w1
Notice how their position (green line, data last updated wednesday before this price drop) still is twice its bottom on 2008).
They are dumping silver positions with it, only that there they already sit since 2 weeks under 2008's bottom
http://finviz.com/futures_charts.ashx?t=SI&p=w1
There are two questions: the degree at which other market segments sell (panic?), and the duration that this lower price level lasts.
$50 lasted a couple days. It was also never revisited since. The same applies to the other side of the swings.
The higher the price, the more silver is needed to be bought to keep it there.
The lower the price, the less silver is needed to be bought to keep it there.
During the past months, a part sold silver. What did they do with the fiatmoney? Did they buy something else (what?) or did they keep the fiat to try to buy more silver? It's not like that the crisis is over.
For my personal case in this, I can't buy silver now, I did it when spot was $29. If this price level or lower lasts longer than a month, I can benefit from it. If it doesnt, well, bad luck. It would be only a few % of the silver I already have.
For those that intend to sell now or in a near future, it might be less good news.