I watched as he opened the sixth seal. There was a great earthquake. The sun turned black like sackcloth made of goat hair, the whole moon turned blood red, and the stars in the sky fell to earth, as figs drop from a fig tree when shaken by a strong wind. The heavens receded like a scroll being rolled up, and every mountain and island was removed from its place. – Revelation 6:12

The Bible tells us that at the time of the Great Tribulation, people on earth will cry for the mountains and rocks to fall on them.  However, the scriptures also explain that those who were slain because of the word of God and the testimony that they had maintained will be found “under the alter” and wearing a white robe given to them by Christ.