Qualifications
A bachelor's degree is a must for becoming a seismologist. No way to wiggle out of that one. You're not going to find too many degree programs that focus strictly on geophysics, though. You'll most likely have to split the difference with your undergrad degree by majoring in either geology or physics. While you're there, a minor in computer science could be super helpful as well. Mad computer skills are going to be handy when you're surrounded by screens in a lab one day.
While you can get some entry-level jobs with a bachelor's, you have to at least get a master's if you want to be a full-fledged seismologist (source). In grad school, you'll be able to delve into geophysics and seismology specifically. You're going to need this degree if you want to be truly competitive; it's the only way you're going to shake off all that competition out there.
If you want to be one of the dudes at the top of the pay scale, you'll need to get a PhD. Big companies and government institutions only give the big bucks to people with "Dr." titles.