The earthquakes began at the end of the second season. They cause the land of the lost to collide with a different dimension with different Marshalls. Rick and Will are able to stop the dimensions from colliding and everything goes back to normal(well as normal as it can get in the land of the lost). Although the fate of the other Marshalls is never discovered the first episode of the 3rd season another earthquake happens. This earthquake marks the beginning of major change. The earthquake sends Rick home,separates Cha-ka from his family,brings Jack to the land of the lost,awakes lulu and possibly torchy ,destroys the high bluff,forces will,holy,ch-ka,and jack to move into an old temple and destroys sleestak tunnel