Zechariah 14:3-4

3Then the Lord will go forth and fight against those nations, as when He fights on a day of battle.

4In that day His feet shall stand on the Mount of Olives, which lies before Jerusalem on the east; and the Mount of Olives will be split in half from the east to the west by a very large valley, and half of the mountain will move toward the north and half of it toward the south.