Thanks to the assistance of the members on this site including          ModestEarner and gddsmith, I received a forwarded notification today. Apparently they accidentally sent the notification to our old email address:

> It looks like we sent it to your old email address instead of the new one.
> My apologies for the inconvenience. I've started an investigation to
> ensure this issue gets resolved for future cases.

Anyway, we've determined the violation was a user on Flickr who uploaded lewd photos and targeted a location. They (or someone else) did a search for that location on our site and the Flickr API displayed the photo. The photo undoubtedly got removed from Flickr for a TOS violation since the URL the Adsense team sent me no longer has lewd content, but to avoid this, I went ahead and removed the Flickr API function from the site.

Thanks everyone for your assistance. Without you, I'd probably be shutting down the site (the income from it pays the hosting bill). We sent our violation appeal in and also mentioned all of the other violations mentioned here and corrections we've made to correct those issues as well.