Bioquake

Bioquakes are a naturally occuring natural disaster that can have catastrophic results. One of the greatest bioquakes ever recorded occured shortly after the Great Cataclysm. It shook all of Metru Nui, causing all not only the destruction of the Chute System and the Archives, but also the awakening of creatures such as Ussal Crabs, Bohrok, Rahkshi, Protodites, a Gukko, and the Visorak.

Little is known of any other bioquakes, but they occur spontaneously.