Maybe they are and maybe they aren't mentioned in bible prophecy. We currently have two of the going one with fury right now, one in Kilauea and another in Guatemala. Earthquakes often come with volcanoes. “You will be punished by the Lord of hosts with thunder and earthquake and great noise, with storm and tempest and the flame of devouring fire” (Isaiah 29:6). These prophecies are often associated with catastrophic events leading up to Christ’s second coming. “Blow the trumpet in Zion, and sound an alarm in My holy mountain! Let all the inhabitants of the land tremble; for the day of the Lord is coming… a day of darkness and gloominess, a day of clouds and thick darkness” (Joel 2:1-2). “They have provoked Me to jealousy by what is not God; they have moved Me to anger by their foolish idols… For a fire is kindled in My anger, and shall burn to the lowest hell; it shall consume the earth with her increase, and set on fire the foundations of the mountains ” (Deuteronomy 32:21-22). The apostle John describes major events leading to the second coming in Revelation. “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 every mountain and island was moved out of its place” Volcanoes cause end-time celestial signs. Nuclear weapons do also. BLOOD MOON Revelation 6:12 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; Matthew 24:29 Immediately after the tribulation of those days shall the sun be darkened, and the moon shall not give her light, and the stars shall fall from heaven, and the powers of the heavens shall be shaken: In Mathew 24:29 Jesus is talking about the cosmic signs at the end of tribulation. Revelation 6 is at the beginning of tribulation. These are not the same cosmic signs. There's a difference between a blood red moon and a darkened moon or one that doesn't give her light. And there's a difference between a darkened sun and one black as sackcloth. There are two reasons why the moon appears red even today. When it first rises or sets the curvature of the earth causes our viewing of it to be through a much longer distance of the particles of the earth's spheres. We see it through a more dense part of the atmosphere and the particles scatter away the blue/green light and let the red light go straight through. When it's high in the sky we view it through much less of a distance through those spheres and it doesn't appear red. It's the particles in those spheres both natural and manmade that cause its appearance to be red. In the beginning of tribulation the moon will appear red all the time and as tribulation progresses you won't be able to see it hardly at all. The moon and stars as well will then fade more as the tribulation progresses. Toward the end of tribulation there will be so much stuff emitted into the atmosphere that we won't see it at all other than a dim glow above those spheres with pollution. The same is true about the sun. In Revelation 6 the sun became black as sackcloth of hair. In Mathew 24:29 the sun is darkened. Sackcloth is a coarse cloth that you can see through a bit. That's different than a sun that is darkened or can't see at all like on a cloudy day. This event has nothing to do with any Jewish festivals or celebrations like so many teach today. In Joel 2:31 we can't be sure if he's referring to the beginning or end of tribulation. All we know is that it's before the Day of the LORD. I tend to believe he's being more general and talking about the entire tribulation period. Joel 2:31 The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of the LORD come.