The fact that the earthquakes were striking randomly, not along well-known geological faultlines, would be proof that something devastating was afoot.
Finally, the end would come, in a disaster of Biblical scale. The Earth would literally start to crack up.
Molten lava would wash over the land and the seas would start to boil.
Mega-hurricanes would level buildings and forests the world over. Eventually, mountains would crumble as the Earth’s crust continued to disintegrate.
The fabric of the planet itself would start to disappear, trillions of tonnes of rock, water, air and life sucked into a whirlpool of unimaginable force.
From space, our blue-and-white home would appear to vanish down a plughole in a flash of light.
At least in this scenario we would have a little time, perhaps, to come to terms with the end.
However, a second doomsday scenario is even more terrifying. There would be no warning at all.
In an instant - about one-twentieth of a second - the entire Earth would simply vanish from space.
Less than two seconds later, the Moon would follow suit. Eight minutes later, the Sun would be ripped apart, followed by the rest of the planets in the solar system and onwards, a wave of destruction caused by a rent in the fabric of space itself, spreading out from our world at the speed of light.
Any extra-terrestrials out there would die too, in due course. And there would be nothing technology could do about it.
But why should we now be worrying about such possible causes of Armageddon?
The answer is a gargantuan machine - the largest, most expensive scientific experiment in history, the ‘Large Hadron Collider’, to be turned on next Wednesday.
Although it was designed to answer the fundamental questions of life, some people have claimed that it could end up destroying the entire cosmos.
This gigantic 4 billion-plus atom-smasher has been built under the Swiss-French border near Geneva, and is the most powerful device ever built for probing the secrets of the atom and the forces and particles which make up our Universe.
It is a staggering device, occupying a train-sized tunnel 18 miles long, buried 300ft underground, studded with gigantic, cathedral-sized ring-shaped detectors where collisions between packets of ‘heavy’ subatomic particles, ‘hadrons’, will take place in the hope that the innermost workings of matter and energy will be revealed.
The LHC is, arguably, the most impressive machine ever built by Mankind.
But a few people are convinced that it should never be turned on. A lawsuit has been lodged at the European Court For Human Rights by a small group of maverick scientists.
They claim there is a small - but not zero - chance that when the LHC is activated it will create either a mini-black hole which would fall into the ground and swallow the Earth from within (scenario one).
Or, even more bizarrely, trigger a catastrophic chain reaction in the very fabric of space and time itself, which would rip apart the entire universe like the skin of a bursting balloon (scenario two).
Bizarrely, this group, led by a German chemist called Otto Rossler, are using the European Convention on human rights to argue that, should the LHC destroy the entire Universe, it would ‘violate the right to life and right to private family life’.
In fact, since 1994, when the collider was first mooted by the multi-national European nuclear research organisation (CERN), a small number of doomsayers have claimed that by replicating the conditions pertaining at the start of the universe (Big Bang), about 13,700 million years ago, there would be a small but real risk an unstoppable cataclysm would take place.
This is not a threat taken seriously by the scientists at CERN. When I visited the place a couple of years ago, to see the collider being built, any mention of mini-black holes and other risks elicited only raised eyebrows and shrugs of derision.
Hopefully is not the end of the day