I’ve been living in the bay area for 14 years and have been through a lot of earthquakes before, but today, this was the longest and largest quake I’ve felt!
This quake was 5.6 on the richter scale and lasted around 12 seconds. It was a very long 10-12 seconds.
I was in the garage at the time taking a car battery out, when all of a sudden I hear this noise upstairs, and this rumbling noise. The ground started to shake, and the whole house was moving quite a lot. Then it stopped for a brief second. Then it continued going with a picked up pace. The scariest thing about it all is not knowing how long it was going to last and if it was going to get stronger. By far this was the largest quake I’ve felt.
For more specific information on the quake:
http://quake.usgs.gov/recenteqs/Quakes/nc40204628.htm
http://earthquake.usgs.gov/earthquakes/eqinthenews/2007/nc40204628/
UPDATE: The earthquake actually lasted about 30 seconds. You can read an article from the San Jose Mercury News, 5.6 quake hits Alum Rock.