In order for CrisisGo to display alerts during an emergency, it may be necessary to modify an iOS device's Notification Center settings. Directions are attached to this article for both iPads and iPhones.
It is also important to note that if an iOS device has the sound muted, an alert will still appear on the screen but the warning siren sound will not be played. The sound can be muted by either turning the level down manually or using the "side switch" above the volume buttons.