Mamad Har Sinai

There is a tradition from the Vilna Gaon that Milchemes Gog and Magog at the time of Moshiach will last only 12 minutes. In that short amount of time 1/3 of the world will be destroyed, 1/3 severely wounded and 1/3 will survive. Until recently this was incomprehensible - how could such destruction happen so quickly?