You need people to submit events in their areas, so how about a gaming mechanic. If you get random people to submit as many events as possible (Don't specifically target the event owner (Only 1 event)) and reward them somehow (Badge, payment, physical prize), it could work.
Make it cool to use SplashActive.
I'd also get rid of the advertising until you are abit more popular, it's just a turn-off that no one will pay for until you have a large user base.
The title in the header could be shortened to "Find activities in your area"
Finally, I hoped you had fun making this, I like it's simplicity.
Good Luck! - Matt