San Francisco Example: 4 seconds after detonation
The shock wave will have an overpressure of 20 psi at a distance of 1.4 miles from the site of the accident. Even the most heavily reinforced structures will be destroyed inside this circle, including Fisherman's Wharf, buildings on Alcatraz Island and a good portion of the north facing waterfront. Any ships inside this ring will be sunk. Roughly one minute later a wave over 50 feet high, created by the blast, will hit the shore.
Only a few square miles of the 20 psi ring are over land. All people inside this ring, about 45,000, are killed by the thermal pulse (attenuated by the fog, but still over 160 calories per square centimeter) or the shock wave.
The fireball will have a maximum radius of 2,695 feet. However, it is completely over water, and does no damage to the nearby structures.