I recently moved from using the Microsoft Exchange sync capability with Google Apps to IMAP, CardDAV, and CalDAV due to some bugs I was hitting. But this meant that all of the shared calendars began firing off alerts for my phone.
Turns out Google offers a page that allows you to toggle which calendars sync with your phone.
- Go to https://www.google.com/calendar/iphoneselect
- And then select which calendars you want to display.
- Save the changes.
Once that is done, open up the calendar app on your iPhone or iOS device and go to the screen where it shows the list of calendars. You should only see (and receive alerts) for the calendars selected previously.