You're right it is a lighthouse. Well is a photo of San Francisco, with Alcatraz in the foreground. I think the island itself is in the same angle that you said that the crashing was heading.The guard tower is in the foreground.I don't know. Maybe. It looked to me like it hit the cellhouse straight down its length, going right over the lighthouse. That would mean it was heading more or less southeast, and if it didn't veer at all, it could've conceivably skidded all the way to the Bay Bridge. That's why I placed landfall somewhere in North Beach. Of course, I guess it could've veered even farther west towards the Marina District when it hit the water, but I think it's the poor sea lions at Pier 39 who are going to have the bad day.
Um, no. Not to belabor the point, but unless you see something I don't, that's the light house you're mistaking for a guard tower. The ruins of the warden's house are next to it (just to its left, our right). Those things are really there, today.
I hope the link works?
http://youshouldstoprunning.com/wp-content/uploads/2013/02/Alcatraz.jpeg