v.12-14 I looked when He opened the sixth seal, and behold, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became like blood. And the stars of heaven fell to the earth, as a fig tree drops its late figs when it is shaken by a mighty wind. Then the sky receded as a scroll when it is rolled up, and every mountain and island was moved out of its place.
With his eye again upon the earth, John witnesses a tremendous cataclysm. First, an earthquake of such magnitude that it’s able to thicken the atmosphere with enough dust and ash to blacken the sun and make the moon appear red like blood (a volcanic eruption can do this). Secondly, what seems to be a meteor shower, John sees stars falling to earth like over-ripened fruit from a tree. And thirdly, a mysterious receding of the sky followed by a violent trembling of every mountain and island on earth. Though we might not fully understand the nature of these events, it is clear that the entire universe is convulsing.
v.15-17 And the kings of the earth, the great men, the rich men, the commanders, the mighty men, every slave and every free man, hid themselves in the caves and in the rocks of the mountains, and said to the mountains and rocks, “Fall on us and hide us from the face of Him who sits on the throne and from the wrath of the Lamb! For the great day of His wrath has come, and who is able to stand?”
Because of these things every man, woman, and child on earth will run for cover inside every crack and crevice they can find and they will acknowledge the work of God but without repentance for it becomes evident later that they aren’t repenting (at least not all of them).
This concludes the first wave of judgments know as the seal-judgments, so-called because they are evoked in concert with our Lord’s removal of the seals from the scroll. Two more waves of judgment will follow, each intensively worse than the one before it.