Question about tier events on Bjora Marches

[Tekoneiric.6817]

On Bjora Marches tiered events; what are the tiers based on? Time or quantity? I've tried to get gold on the Cleanse the corrupted Eagle shrine event but it never rewards a tier. The wiki doesn't say what the tiers are based on.

[Hesione.9412]

Gold refers to the level of participation, which pops up once the event finishes (you'll also get some money and some karma). If you contribute to the event, you'll either get a bronze, silver, or gold medal. About halfway down this page, on the right, is the type of dialog box that will turn up once the event finishes:

https://wiki.guildwars2.com/wiki/Dynamic_event#Event_participation