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Okay, I've spent too much time looking for this book, it's time to ask for help. Around 10 or more years ago I've read a book about a young person (possibly a girl but I'm not sure). The main theme of the book was that the world's culture was based on magic, which was based on the runes. There was some kind of an earthquake (?) after which the magic stopped to work. It was really weak and had no more use of it. Eventually the hero found out that the runes were basically the map of the world (city?) with added lines, and that the earthquake created an abyss which had to be represented on the 'map' for runes to work. At the end of the book was awesome list (dictionary) of those runes with drawn symbols and written spells. I tried everything and can't find this book. I'm desperate. Sorry for any grammar mistakes, not a native speaker.