Albert Barnes Commentary 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 be cleft 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." — Zechariah 14:4 (ASV)

And His feet shall stand in that day upon the Mount of Olives – “Opposite Jerusalem to the east, where rises the Sun of Righteousness.” The Mount of Olives is the central eminence of a line of hills, a little more than a mile in length, overhanging the city, from which it is separated only by the narrow bed of the valley of the brook Cedron.

It rises 187 feet above Mount Zion, 295 feet above Mount Moriah, and 443 feet above Gethsemane. It lies between the city and the wilderness toward the Dead Sea; around its northern side, the road to Bethany and the Jordan wound.

There, David probably worshiped (2 Samuel 15:32); his son, in his decay, profaned it (1 Kings 11:7); Josiah desecrated his desecrations (2 Kings 23:13). There, upon the mountain, which is on the east side of the city, the glory of the Lord stood, when it had gone up from the midst of the city (Ezekiel 11:23). The Mount of Olives united the greatest glory of the Lord on earth, His Ascension, with His deepest sorrow, in Gethsemane.

Since the angel said, This same Jesus, which is taken up from you into heaven, shall so come in like manner as ye have seen Him go into heaven (Acts 1:11), the old traditional opinion is not improbable: that our Lord will come again to judge the earth where He left the earth, near the place of His agony and crucifixion for us.

So will the Feet of God literally stand upon the Mount of Olives. Elsewhere it may be that “the Feet of the uncircumscribed and simple God are to be understood not materially, but that the loving and fixed assistance of His power is expressed by that name” (Dionysius).

Which of these is true, or whether, according to an old opinion, the last act of antichrist will be an attempt to imitate the Ascension of Christ (as the first antichrist, Simon Magus, was said to have met his death in some attempt to fly) and be destroyed by His Coming there, the event must show.

And the Mount of Olives shall cleave – (be cleft) in (from) the midst thereof toward the east and toward the west – that is, the cleft will be east and west – so as to form a very great valley through it, from Jerusalem toward the Jordan eastward; and this will be, in that half of the mountain shall remove northward, and half thereof southward.

If this is literal, it is to form an actual way of escape from Jerusalem. If figurative, it symbolizes how that which would be the greatest hindrance to escape—the mountain which was higher than the city, blocking, as it were, the way—would itself afford the way of escape.

This is as Zechariah speaks, O great mountain, before Zerubbabel thou shalt become a plain (Zechariah 4:7); and Isaiah, Every valley shall be exalted and every mountain and hill shall be brought low, and the crooked shall be made straight, and the rough places plain (Isaiah 40:4). That is, every obstacle will be removed.