Either way, a starship in the JJverse crashing into a city would cause major damage to a city. The Dreadnought ship is nearly a mile long. San Francisco is over 7 miles in length from bay to ocean, so at least 1/6th of the city will be destroyed by this ship.
Based on the trajectory of this ship, northeastern San Francisco will be utterly destroyed by this behemoth. The question is, how far will this ship go into the city?
And, according to this map, the distance from Alcatraz to Fisherman's Wharf is approximately a mile or so. (http://upload.wikimedia.org/wikipedi...tricts_map.png