What role does the great earthquake play in the end of the tribulation?
The great earthquake occurs at the midpoint of the tribulation, in Revelation 6 and 11, and it triggers or sets in motion the final events of the last three and a half years. After those events run their course, Christ returns to the Mount of Olives and establishes His Kingdom.
Les explains that at the midpoint of the tribulation, after the two witnesses are resurrected and ascend into heaven, the Antichrist comes to the temple, defiles it, forces the Jew to stop temple worship and worship him, triggering awful persecution during the final three and a half years. One of the other big midpoint events is a tremendous earthquake, mentioned in Revelation 6 and 11. That great earthquake triggers or sets in motion the final events of that last three and a half years. Once those events run their course, Christ returns to the Mount of Olives, sets up His Kingdom, the curse is lifted, Israel becomes the top nation, and the rest of the world comes under the blessings of the covenant given to Abraham.