The IP addresses might not be accurate location. I live in Rochester, New York, but when I log onto Facebook from my iPad it says I am logging in from Cleveland, Ohio (258 miles away).
Wish I could help you. If it's happened 10 times, I doubt they could be guessing the password (1 or 2 times, maybe), so coming up with a more complicated password (like 30 characters, letters, and numbers) probably wouldn't help. I will let someone with more knowledge of this stuff help.