I have come to believe that the opening of the sixth seal in Revelation is meant to serve as an indisputable sign to the world, that we are indeed in the End of Days.. We have argued that the End of Days actually began decades ago with the opening of the first seal that unleashed the first horseman, the rider on a white horse. We can see evidence that the second, third, fourth, and fifth seals have also been opened. Though the evidence is strong, it is not conclusive. The events surrounding the opening of the sixth seal with rock the entire world, and in doing so, serve as a wake up call that we are indeed in the End of Days.
In Revelation 6:12-17:
And I beheld when he had opened the sixth seal, and, lo, there was a great earthquake; and the sun became black as sackcloth of hair, and the moon became as blood;
13And the stars of heaven fell unto the earth, even as a fig tree casteth her untimely figs, when she is shaken of a mighty wind.
14And the heaven departed as a scroll when it is rolled together; and every mountain and island were moved out of their places.
15And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men, and every bondman, and every free man, hid themselves in the dens and in the rocks of the mountains;
16And said to the mountains and rocks, Fall on us, and hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb:
17For the great day of his wrath is come; and who shall be able to stand?
Though the world has experienced many great earthquakes, the earthquake that will occur with the opening of the sixth seal is special. This earthquake will cause day to turn to the darkest night, and will hide the stars at night, and if you can see the moon, it will have turned the color of blood red. The events following this earthquake will cause the rich and powerful of the world to hide in their mountainside bunkers, and the poor will seek shelter where they can. This site has repeatedly argued that a major eruption of a super volcano could serve to fulfill this prophecy.
In a recently published scientific research paper, the authors argue that the trigger for super volcano eruptions is different from that of normal volcanoes. A normal volcano will typically erupt when magma builds up underneath the volcano. When the magma buildup reaches a certain point, the volcano erupts. In the case of a super volcano, the research argues that a major super volcano eruption is triggered when the ‘lid’ that covers the super volcano caldera weakens and breaks. The most likely cause of such an event would be an earthquake of sufficient strength to cause cracks in the ‘lid’. Should the cracks be large enough, pressurized gas would then explode outward, breaking the lid, and causing a major eruption.
http://www.iflscience.com/environment/what-actually-causes-supervolcanic-eruption
The scenario laid out by this research fits in well with the events as described in Revelation. A major earthquake occurs at the top of the super volcano, cracking the lid sufficiently to weaken it, and it caves in. The super volcano then spews out enough ash and smoke to darken the skies over the Western Hemisphere, causing all the rich and powerful to flee to their mountain bunkers (with everyone else left to seek shelter in their basements). The repercussions of such an eruption could further serve to facilitate other prophecies found in Revelation.
If we are correct in our belief that the fifth seal has already been opened, then in the not so distant future, we expect a devastating natural calamity to occur that will darken the sky and cause both the rich and the poor to seek shelter underground. Best to make some preparations.