If we keep in mind the perspective of the 1st audience then we will find it easier to discover the meanings of the prophesies of Revelation. Rev. 1:1 stated the time, "things which must shortly come to pass..." Rev. 1:7 said that those who pierced Him would see His coming. Those who pierced Him were those who crucified Him, and those caused Him to be crucified who lived in the 1st century AD (BCE).
The temple was still standing when the Revelation was given to John (Rev. 11:1-2), and when Christ told him that he would prophesy again to many people (Rev. 10:11). Revelation was shown to John to take the message to the first century churches. They were told Christ was coming quickly. The book opens with that message, and closes with it five times in chap. 22 (vs. 6, 7, 10, 12, & 20).
As it is a book of prophesy then we must consider the usage of prophetic metaphors established from the OT judgment language. A coming of the Lord was always used for the presence of God coming in judgment against the wicked.
"For, lo, Jehovah is coming out of His place, To charge the iniquity of the inhabitant of the earth upon him, And revealed hath the earth her blood, Nor doth she cover any more her slain!'" (Isa. 26:21, YLT)
"And caused to be heard hath Jehovah The honour of His voice, And the coming down of His arm He doth shew with the raging of anger, And the flame of a consuming fire, Scattering, and inundation, and hailstone." (Isa. 30:30, YLT)
The "earth" was used for the land or occupied territory / region of the people who were being warned of the coming judgment. As the prophet of Revelation was Jesus (Rev. 1:1), and as Jesus was sent to the lost sheep of the house of Israel (Matt. 15:24), and as John was being sent again to prophesy to the seven churches in Asia, then the "earth" was the lands of Judah and those nations / people of the Roman empire which existed in the 1st century A.D.
The "earth" then in Rev. 1:7 were all the tribes / peoples of all of the nations which the Roman empire had conquered, but specifically that of Judah, the remnant of Israel which God had maintained for the manifestation of the Messiah, the savior. Those were the tribes / people who wailed because of Him.
Jer. 9:11-19 -
"11 And I will make Jerusalem heaps, and a den of dragons; and I will make the cities of Judah desolate, without an inhabitant.
12 Who is the wise man, that may understand this? and who is he to whom the mouth of the Lord hath spoken, that he may declare it, for what the land perisheth and is burned up like a wilderness, that none passeth through?
13 And the Lord saith, Because they have forsaken my law which I set before them, and have not obeyed my voice, neither walked therein;
14 But have walked after the imagination of their own heart, and after Baalim, which their fathers taught them:
15 Therefore thus saith the Lord of hosts, the God of Israel; Behold, I will feed them, even this people, with wormwood, and give them water of gall to drink.
16 I will scatter them also among the heathen, whom neither they nor their fathers have known: and I will send a sword after them, till I have consumed them.
17 Thus saith the Lord of hosts, Consider ye, and call for the mourning women, that they may come; and send for cunning women, that they may come:
18 And let them make haste, and take up a wailing for us, that our eyes may run down with tears, and our eyelids gush out with waters.
19 For a voice of wailing is heard out of Zion, How are we spoiled! we are greatly confounded, because we have forsaken the land, because our dwellings have cast us out." (KJV)
The first fulfillment of this prophesy was the destruction of Jerusalem (Zion) approx. 539 BC in the Babylonian captivity. The double or second fulfillment was in the destruction of Jerusalem and the 2nd temple in A.D. 70 and the people of the land (the earth) of Jerusalem and all Judea wailed because of Him. They saw His coming in the results of that destruction and in the Roman army which laid that city waste / desolate.