zechariah 14:4 And his feet shall stand in that day upon the mount of Olives, which is before Jerusalem on the east, and the mount of Olives shall cleave in the midst thereof toward the east and toward the west, and there shall be a very great valley; and half of the mountain shall remove toward the north, and half of it toward the south. - Free Bible Online

      4. The object of the cleaving of the mount in two by a fissure or valley (a prolongation of the valley of Jehoshaphat, and extending from Jerusalem on the west towards Jordan, eastward) is to open a way of escape to the besieged (compare Joe 3:12, 14). Half the divided mount is thereby forced northward, half southward; the valley running between. The place of His departure at His ascension shall be the place of His return: and the "manner" of His return also shall be similar (Ac 1:11). He shall probably "come from the east" (Mt 24:27). He so made His triumphal entry into the city from the Mount of Olives from the east (Mt 21:1-10). This was the scene of His agony: so it shall be the scene of His glory. Compare Eze 11:23, with Eze 43:2, "from the way of the east."

JFB.