You could also try looking at http://thegradcafe.com
, which has discussion forums for the graduate application process, being a grad student, etc. for all disciplines!
My undergrad was in physics/astrophysics, masters in astronomy and now I'm at a Planetary Science program in the US (so I'm an international student too!) and here, Geophysics and Planetary Sciences are grouped in the same department. I think most of the Geophysics students here come from geophysics undergrad programs but I think cross-discipline fields, such as geophysics, tend to accept strong students from a variety of backgrounds. I know that my cohort of planetary scientists are a mix of physics, astronomy, geology, and earth science undergrads!
So, my short and educated guess would be that having a theoretical physics background isn't going to rule you out of many programs. What's important is to demonstrate that you show and motivate your desire to do a Geophysics PhD. But I would recommend you talk to geophysics departments and check out thegradcafe forums linked above!