David Nosbusch

Data coverage is usually not available or overwhelmed in these scenarios. I think it would be more reliable for FB to send an SMS to the phone number you (may have) given them, where you could respond quickly with a Y or N, to conserve valuable cell tower resources in the area impacted.

what is the resolution on the "crowd?" is the algorithm optimized for larger public events or could this be used for smaller private events (parties, weddings, etc)?