Waiting for an apocalypse from Mother Nature? Are we ready for a continent-wide major earthquake? For a decade of severe food shortages after a major volcanic event? Do you even think about the curve-balls that keep being flung at humanity?
Human record keeping is spotty, and having a global network that reports and records major geological events only got going in the 19th Century with the onset of telegraphy and newspapers. There was a lot that happened in the depths of history that we never understood until very recently.
The emergence of multi-disciplinary approaches to archeology and paleontology have filled in some of the gaps in our knowledge. In the last couple of decades, it has slowly dawned on many scientists that civilization, if not our existence, is more precarious than we know.
We’re always being peppered with big rocks from space. Kilometer-wide rocks (approximating 50,000 Megatons of TNT) hit every 400,000 years – these could be horrific, but the last one splashed into the Pacific off the uninhabited Southwest coast of New Zealand in the 15th Century. The only people who may have noticed were Tasmanian coastal Aborigines, and very few would have survived the massive Tsunami.
We get hit by 20m wide rocks hit every 60 years or so. We shouldn’t see a repeat of the 2013 Chelyabinsk Meteor for a few decades… probably. The next one might finally show what a rock of that size can do to a city, but the energy release is comparable to a nuclear weapon in the megaton range.
Major volcanic events seem to be reliably linked to periods of major famine and epidemic in history – having lousy crops for the better part of a decade due to dust in the high atmosphere can do that.
The Volcanic Explosivity Index (VEI) charts the severity of volcanic explosions – which can shroud our whole planet in dust and ash. A VEI Level 8 event (Toba) nearly wiped out the entire human race in our infancy around 72,000 years ago. Level 7 events like Thera (3,620 years ago) and Tambora (1815 AD) usually triggered widespread and severe hardship.
We shouldn’t expect an event of these magnitudes in this century… but the Yellowstone Super-Volcano (VEI of 8) could happen ‘soon’. In geological terms, this could be tomorrow or 100,000 years from now. We can expect one or two Level 6 (Krakatoa) events and six or seven Level 5 (Mount Saint Helens) eruptions in the balance of this century. This is not the stuff of an apocalypse, but the effects could still be widespread and disruptive.
Lots of earthquakes have been deadly and destructive, especially if combined with a tsunami. While the effect of an earthquake can be highly variable, the greater the magnitude, the greater the potential. The 19th Century saw two earthquakes that were around 9.0 on the Movement Magnitude Scale (er, forget the old Richter scale). The 20th Century had one off Alaska in 1964 and we believe there was one in the 18th Century. We can expect one, somewhere and sometime, in this century.
We know that apocalyptic geophysical events occur but we’re probably not due for one in our lifetime. However, playing the odds in the catastrophe lottery isn’t smart in the long run. Some “how to save civilization” preparation would always be prudent.