@DoubleAA Interesting. That might qualify as tzara b'makom yadu'a' b'Yisra'el, in which case the Ramban would either hold that people must fast 24 hour fasts (Beit Yosef, Bach) or that it might be appropriate to do so (Vayigash Y'huda, though he says that this would be dependent on the practice of prior generations - since they weren't strict we aren't strict).
