Crispin has an apartment in the central city of Wellington. Last night I snuck into his apartment while he was having a shower, spread myself out on his double bed and undressed right down to my sexiest black lingerie, exposing my erect nipples. I think Crispin freaked when he first noticed there was an intruder, but the adrenaline must’ve paid off when he noticed who it was. His towel was bursting; it seemed he had acquired a third leg. Needless to say, my third leg massager was self-lubricated.

What followed was a session of intensely satisfying and vigorous love-making. Crispin is a butterfly swimmer, and testimony to the buttock-toning abilities of the dolphin kick. As Angus Young would have said, he shook me all night long, but given the audible movements of his bedside ornaments and furniture, I was just a little conscious of who else he might have shook.

I awoke the next morning to the terrible news of a catastrophic earthquake in Los Angeles which killed more than 30,000 people! The initial shock provoked a tremendous feeling of guilt in me. We may have disturbed the neighbours last night, but surely we hadn’t caused anything more devastating than that.

I couldn’t help but think about the butterfly effect of chaos theory. If the flapping of a butterfly’s wings in Brazil could set off a monstrous tornado in Texas, then what trouble could be caused by the flapping of a butterfly swimmer’s buttocks in Wellington? In the midst of our unbridled passion, I fear that our pelvic movements were significantly more energetic than the delicate yet tornado-inducing flapping of a butterfly’s wings. Could it be merely coincidental that both Wellington and Los Angeles lie on the outskirts of the same tectonic plate, the Pacific Plate, the shifting of which has given birth to the Southern Alps, the Hollywood Hills and who knows what else?

Hippies are fond of preaching “make love not war”, but if making love can lead to as many deaths as the Vietnam War and the Second World War combined, then does that make me some sort of love-criminal? Could Crispin and I ever be held responsible for these man slaughtering love-crimes against humanity? Or are longitudinal seismic waves a tragically inevitable consequence of sexual encounters on our planet’s geology?

Emma

A  You are correct that it is possible that your sexual liaisons were the trigger for the catastrophic earthquake leading to the death of those poor people in Los Angeles but, in the unlikely event that you are a man slaughtering love-criminal, you will never be convicted thanks to the human limitations of law enforcement.

The Butterfly Effect of which you spoke is the essence of chaos theory and may be technically described as the sensitivity of chaotic systems to initial conditions. It was initially discovered by Edward Lorenz when he observed such sensitivity and unpredictability in his computer models of weather systems. This led to the assertion at an American science conference that a butterfly flapping its wings in Brazil could create small air currents and disturbances which could propagate unpredictably to set off a tornado in Texas. Natural disasters in America could now be blamed on the third world.

The crust of the Earth is more accurately described by a theory called self-organized criticality. Over hundreds of millions of years of earthquakes and volcanic activity the Earth’s crust has self-organized into a critical state at the boundary between order and chaos, displaying fractal patterns in fault lines, rivers and coastlines and power laws in the distributions of catastrophic events such as earthquakes. Because of the sensitivity of the critical state to small changes, the Butterfly Effect again applies – a small perturbation can eventually affect the behavior of the system everywhere.

It is perfectly conceivable that your naively enthusiastic pelvic tucks created low-frequency, low-amplitude vibrations in the South-West edge of the Earth’s Pacific Plate that could have propagated unpredictably through the Earth’s crust and geological layers, causing the force at the weakest site in the tectonic plate to exceed the threshold for breakage and to propagate, eventually causing a tectonic movement on the other side of the Pacific Ocean.

Though while this is in the realm of possibility, it is far from likelihood. Statisticians estimate that at any point in time there are around 2000 couples engaging in some form of sexual intercourse. On the night of the Los Angeles earthquake, around 2.5 million couples would have been having sex on the Pacific Rim alone. It would be drastically unethical and morally inexpedient to pin the cause of the earthquake down on any one of these couples individually without knowing the detailed fault structure and the forces that were acting on those faults everywhere throughout the Pacific Plate. Both the lack of geological data and your anonymity in a crowd of Pacific Rim sex participants will save you from prosecution in the unlikely event of guilt.

But even if we did have the foresight to identify and remove that fatal triggering pelvic thrust, complexity theory says that there would sooner or later be another earthquake, originating somewhere else, perhaps with equally devastating consequences. The power law distribution of earthquake magnitudes is a property of the Earth’s crust being in the critical state, and large earthquakes cannot be removed from this distribution by removing their source.