The Shaking

Chapter Five

11.16. UKGeoScan head office; Cambridge.

Dr Brian McLean's busy fingers typed out a series of complex instructions: Finishing, he tapped the enter key with a final emphatic jab and waited for the powerful mainfraime connected with his terminal to process his commands. It didn't take long for the request to be completed and the data returned.

The results startled the geologist. Never before had he seen anything like it. On his monitor a map of south-east England was displayed, upon which was superimposed a diagonal slash running from Kent northwestward towards London; it was the well-known minor intraplate fault underlying the area which produced weak earthquakes from time to time. Rendered in a scale of vivid colours it showed the electrical potential of the ground as neasured by a newly installed experimental array of deeply buried resistivity sensors.

To a lay person the data would be meaningless, but to McLean what he saw shocked him - no, scared him shitless. If the readings were correct, and he hoped they were wrong, the piezoelectrical signals indicated the tectonic forces were building rapidly again along the underground fissure; the squeezing of the fault being reflected in the increased potential. Put simply, the risk of a significant earthquake was growing.

But it wasn't only the strain building on the known feature which alarmed him, McClean suspected pressure was being transferred to the fault from a deeper rift laying far below the Kentish fracture, beyond the detector array's range. Just as a champagne cork contained the carbonated gases held within a shaken bottle, so a triggering of the upper fault would remove the restraint preventing a far greater force from being loosed. And just as uncorking a gaseous bottle, the energy would be released abruptly.

Brian felt impelled to act on these findings, but first he needed to absolutely sure of his facts; he ran the programme again, only this time changing a few of the variables and excluding some of the more spurious measurements. Then he conducted a further series of calibration and diagnostic exercises. Despite some expected differences in the detail, the results came back much the same as before.

McClean called over to his colleague Michael Wilson, who was also in the office.

"Hey Mike, can you take a look at this please?"

"What's up?" replied Wilson, walking over to the terminal.

Quickly Brian summarised his observations and hypothesis. Michael pondered for a moment.

"I'm not convinced." he said. "There could be any number of reasons for what we're seeing; the most obvious being the electroseismic aftereffects of the previous tremor there. Or it might be a case of electrical earthing into the soil; don't forget there's quite a lot of construction and ground disturbance activity going on in the area, not to mention those exploratory fracking drillings, any one of those factors could explain it."

"Well explain this!" McLean retorted, his swift keystrokes and mouse clicks bringing up another image. "This was the same area a week before the last 'quake; this the day before, and this nine hours prior to the event.

"Yes, but it's easy to spot things in retrospect..."

"Now let's run the model into the future. What do you see now?"

Wilson watched as new branches of false coloured stress began radiating from the fault; the branchlike tendrils spreading into the Kent Downs and as far as St Mary's Bay on the coast.

"Whoa there!" Wilson exclaimed. "You know as well as I that correlation does not equal causation. At a guess, and this is a pure gut reaction, I'd say you were dealing with a model artifact. It can't cope with the data because its not had a long enough baseline to work with. The algorithms are extrapolating an incomplete dataset and presenting outliers as the mean. They're adding two and two together but coming up with five, or in this case several thousand. That or it's being swamped with too much poor quality data as a result of the event and can't discriminate what's real from the background noise. If you were to aggregate everything you'd be bound to arrive at an apocalyptic outcome."