Interesting, what are the "DUMB" tunnels?

At the 6th seal, there will be a massive earthquake (followed by a total solar eclipse and a total lunar eclipse) wicked will crawl into caves attempting to hide from God's judgment.

Rev. 6
12 I looked when He broke the sixth seal, and there was a great earthquake; and the sun became black as sackcloth made of hair, and the whole moon became like blood;
13 and the stars of the sky fell to the earth, as a fig tree casts its unripe figs when shaken by a great wind.
14 The sky was split apart like a scroll when it is rolled up, and every mountain and island were moved out of their places.
15 Then the kings of the earth and the great men and the commanders and the rich and the strong and every slave and free man hid themselves in the caves and among the rocks of the mountains;
16 and they *said to the mountains and to the rocks, "Fall on us and hide us from the presence of Him who sits on the throne, and from the wrath of the Lamb;
17 for the great day of their wrath has come, and who is able to stand?"