I love the city of San Francisco and have always wanted to live there. This book reminded me of one reason not to move there (maybe the only one, really): the earthquakes.
It's kind of a weird book. It starts out as a history of the settlement of California, detailing the problems (lack of water, earthquakes), and hypothesizes that it was a land that should never have been settled in the first place. All well and good.
The second half of the book is more of a doomsday prophecy, in which the author writes in the first person as though the Bay Area has been more or less annihilated by a massive earthquake. He describes desperately trying to locate his children and wife, the damage done to the bridges, expensive houses more or less sliding off of cliffs. It's scarily convincing. I emailed someone I know who lives in San Francisco a few days after reading the book and mentioned it to her. She told me that they had just had a minor quake that week, but that she felt the big one was coming. It just gives you chills.