The quebrada ("broken") is an old tango move. According to John Charles Chasteen in "Black Kings, blackface carnival, and nineteenth century origins of the tango" (in Latin American Popular Culture: An Introduction, pp. 43-60), quebrada comes from a parent dance of tango, the candombe. Candombe was done with quebrada, which meant that there was a break in the line of the body at the waist "to generate sinuous, subtle, flowing motion, without bounding knees or flailing limbs" (Chasteen 2000:46).
In modern tango, quebrada allows the leader to twist, so that the follower can turn around a stable center that is really anchored. This makes turns and changes of direction have a lot more power, as the leader is not easily destabilized. It also looks cool! Don't we all want that "sinuous, subtle, flowing motion?"
Main points to remember:
- In the quebrada position, 70% of your weight is on your front foot, and 30% is on the back foot.
- Make sure your knees "kiss" each other, with the front of one knee pressed against the back of the other knee.
- Make a tripod with your feet: your back foot is behind and slightly sideways to your main support foot. I see a lot of folks try to do this with their feet touching, or right behind each other like a tightrope walker. Try to make a wider stance, and you'll find you have better balance.
- Continue the twist of the quebrada all the way from the floor to your embrace. The spiral in your body allows for a LOT of energy to be generated for movement, or absorbed from the follower.
Here's a clip from Body Dynamics class summarizing this in picture form.
Here's a clip of my teacher, Oscar Mandagaran, rocking the quebrada with Georgina Vargas. Notice how many times he uses the shape of the quebrada in this performance. And, yes, it's not their social dance tango. Yes, it's show tango, BUT he uses it like this on the dance floor, too.