finding a book for my wife?

Quite some time ago (measuring in years) my wife had a book that told the story of a young girls life prior to and after the 1906 San Francisco earthquake. Unfortunately she lent the book out and never received it back (hate that!!) Her problem is she can neither remember title nor author.

The basic plot runs

• young girl finds herself in San Francisco

• Landlord want favours in place of rent

• Girl falls into life as prostitute to pay rent

• Finds a lover

• His family finds out about her history, and upset ensues

• Earthquake hit

• Both lovers think each other has been killed in the quake

• But find each other at end of story

If anyone can point to likely titles it would help

Thanks