A Verneshot (named as a reference to Jules Verne) is hypothetical natural disaster that could explain several mass extinction events in the Earth's prehistory. Some of these major extinction events (such as the Cretaceous–Tertiary extinction event) show evidence of both major geologic upheaval (earthquakes and volcanic eruptions) and also signs of a massive asteroid impact. The odds of an huge space rock hitting at about the same time as a massive volcano erupting is relatively slim, so some scientists have been looking at other possible explanations, such as the Verneshot.
A Verneshot is a (theoretical) case where the volcanic eruption of a supervolcano (or a superheated gas pocket under an otherwise stable craton) hurls a huge amount of rock or magma from the crust and mantle high into the sky. Not quite reaching escape velocity, the molten rock instead succumbs to the old adage "what goes up must come down." When it does so, it may create an impact crater 100 miles in diameter!
Game and Story Use
- This is for the GM who absolutely pulls no punches. You get all the thrills and dangers of a volcanic eruption followed immediately by the world-ending devastation of a major asteroid impact. If you want your campaign to go out with a bang, have Cthulhu or a Mad Scientist trigger a Verneshot. "Game Over, man!" / "Rocks fall, everybody dies."
- Post Apocalyptic settings could have this in their back story, whether the PCs know it or not.
- A Verneshot would be really devastating - it'd be hard to predict, and probably impossible to prevent. This would allow you to have scattered pockets of survivors who still have technology, as well as fearful enclaves who erroneously blame technology or man's arrogance instead of mother nature.
- The eruption and ejection could spread all sorts of strange materials over the new surface of the Earth. In the actual Verneshot theory, it's proposed that the dusting of iridium on the surface around the time of the Cretaceous–Tertiary extinction event came from deep within the Earth - but standard geology models don't expect there to be much iridium beneath the crust in the first place. Likewise, the GM could use this to introduce phlebotinum into the post-apocalyptic setting, change mineral scarcity for whatever purpose, or justify mutation rates a la Gamma World.
- This gives a good excuse to rework the map of the world. All that rock has to come from somewhere. Pick your favorite (or least favorite) continent and place a huge crater or volcano in the middle. You could even remove a continent (sunk beneath the waves), or a whole continental plate, as it's been blown sky-high. Depending on where and how it plays out, you could add a landing site or even dot the world with smaller impact craters. If the Verneshot blasted a coastal area, you could add a new continent or island chain.
- A coastal Verneshot blast might also vaporize or eject a lot of water. This could dry up or drain an ocean, change the climate and cause global warming as the water vapor in the air works as a greenhouse gas. If this gets out of hand, the Earth could end up becoming more like Venus.
- Under the right conditions, the rocky body of a Verneshot could actually leave the atmosphere and gravity of a planet. This could be used as the source or justification for a weird moon, uncharted asteroid, rogue planet, etc. Such a disaster happening on one planet could potentially threaten another world in the same system many months or years later.