On April 4, 2010, I experienced a 7.2 earthquake that was centered south of Mexicali. I was in San Diego, which is pretty far away, but the quake was strong and lasted about 40 seconds. Before the quake, I had been eying the area where it was centered. I had learned that it was a part of a rifting zone. In a rifting zone, the ground within the rift's trough sinks. This article shows us what may well be the further lowering of a rifting trough. Is that indeed so? Thus my constant study and research.

Here is the article:

http://abcnews.go.com/Technology/wireStory?id=12417829&tqkw=&tqshow=