And
the sky was split apart like a scroll when it is rolled up, and
This is difficult to understand. Isaiah 34:4 indicates the host (stars) of heaven are dissolved and rolled together as a scroll. Apparently, the very hot large object moving through the atmosphere will cause the atmosphere to appear to separate and then fold back in upon itself like a scroll. What is clear from this verse is that what hits the earth has come from above (outer space).
every mountain and island (undersea mountain) were moved out of their places.
How was this shown to John? He didn't have the Global Positioning Satellite (GPS) system. Yet he wrote (Revelation 1:11) what he saw.