If you're into technical analysis you know that price structures (a.k.a. support and resistance) are key levels to watch and that markets tend to respect them as turning points. It's very likely that a resistance, once broken, will turn into support and vice versa.
This is a clear example: you can see how the price level in the yellow box (around $700) has been tested many times in the past and has always produced some sort of reaction; today's spike confirms the strength of such level, hinting good buying pressure.