The San Andres fault line can only be visible in certain areas because of the angle you are on, how close you are to the fault. and the weather. If the weather is rainy and foggy, you wont be able to see it. If you are standing 10 miles away from the fault, you may not see it because the fault goes downwards so it may appear flat, and it may just appear as more ground. and if you are very high up, (in space) The fault may not show because it seems extremely small from so high up, it may just look like a sliver of blackness.