I have read several commentaries on this portion of scripture and see it causes a lot of confusion because the most probable meaning is that it is not associated with the first coming of Messiah but the second coming. Originally I may have fell into the 'destruction of Jerusalem' trap because Jesus spoke about the destruction of Jerusalem while sitting on 'Mount Olives' (Matth 24:3) However this is also followed by warning of his second coming, so there is no need to go that direction.
The reason why I have moved to this new position is:
First, because during the destruction of Jerusalem under Tutus half were not spared and delivered and although it may be symbolic the symbolism just does not seem to fit well. Second, the Lord's appearance to save his people 'when all the nations are arrayed against them' is too similar to the images that revelation sets up concerning the second coming of Christ. Third, the fact that so many commentaries differ in their view on the meaning of this chapter is similar to how varied commentaries are on the book of revelation so the uncertainty indicates future fulfillment which is always unclear.
The idea of the section is that on the 'day' that the Lord goes out and fights against the nations his feet will touch Mount of Olives, and the occurring earthquake of his appearance will be split it into two, forming a great valley to flee through...'Then the Lord my God will come, and all the holy ones with him.'
From the standpoint of assigning this to his second coming, the Mountain being split and the people running from Jerusalem has no direct relation to the earlier two mountains. Actually in this context the mountain is simply some large barrier that is preventing escape under impending doom. On one side are enemies and the other a barrier. I can't help but accept those commentaries that think the passing through the Red Sea is being alluded to. In this sense the second coming of Christ, will make an appearance when the world is arrayed against the invisible church. At his appearing a horrible earthquake (a recognition of his power) will cause the barrier to open up and create a valley of escape, just like the passage through the Red Sea.
I do not really dare to say anything more because I confess much about end times prophecy is unclear to me and I do not follow anyone (yet) who pretends a detailed account of what will occur.
The source that made the clearest sense to me on this is Keil. He does not exactly argue everything I have (for example the Red Sea allusion) but Keil is pretty close to this in overall vision (though not seeming to limit it to the second coming only but possibly more generally). Anyway regardless of Keil is really arguing a key verse for me that triggers the concept of the second coming is 14:5 where after the believers flee into the way of escape it is said , 'Then the Lord my God will come, and all the holy ones with him.' Here Keil makes an important note:
The saints here, according to the analogy of other passages (Deut. 33:2, 3; Dan. 7:9, 10; Matt. 25:31; Rev. 19:14), are the holy angels, and not (Vitringa) both holy angels and holy men. (Commentary Zechariah, Keil, p110)
Lange's commentary series (Chambers of Zechariah) seems to pretty much copied Keil word for word in his commentary (he must have forgotten to add the quotation reference!):
The saints here, according to the analogy of other passages (Deut. 33:2, 3; Dan. 7:9, 10; Matt. 25:31; Rev. 19:14), are the holy angels, and not (Vitringa) both holy angels and holy men. (Commentary Zechariah, TALBOT W. CHAMBERS, D. D. p111)
Christ coming with all his holy angels is a major indicator of his second coming. One could take it more generally and say it is not the second coming but a symbol of his saving his people over and over again until the second coming but that does not explain a 'running out' of Jerusalem. That idea would indicate a running to Jerusalem. No, I think we are talking about the end of the age, where the unexpected direction indicates nothing logical about the old way of life. It the end of the world has arrived and the old Jerusalem will be made new to be a new habitation, the old one no longer having significance at the close of human history as we know it.
This is what will happen in that day:When Gog attacks the land of Israel, my hot anger will be aroused, declares the Sovereign Lord. In my zeal and fiery wrath I declare that at that time there shall be a great earthquake in the land of Israel. The fish in the sea, the birds in the sky, the beasts of the field, every creature that moves along the ground, and all the people on the face of the earth will tremble at my presence. The mountains will be overturned, the cliffs will crumble and every wall will fall to the ground. (Ezekiel 38:18-20, NIV)
Under this view interestingly the four winds that you mention does have a place:
When the thousand years are over, Satan will be released from his prison and will go out to deceive the nations in the four corners of the earth —Gog and Magog —and to gather them for battle. In number they are like the sand on the seashore. They marched across the breadth of the earth and surrounded the camp of God’s people, the city he loves. But fire came down from heaven and devoured them. (Revelation 20:7-9, NIV)