From David Coomer.
I LEFT Jersey some 20-odd years ago, but keep in touch with family on the Island. My daughter recently showed me a copy of the JEP with the story of the strange hum in St Ouen.

- I lived for a while in a remote area of the Black Mountains, right on the Herefordshire/Welsh border, where I repeatedly experienced the same phenomenon as described over a period of two years.

- It truly does sound like an engine on tick-over some distance away, and I deeply sympathise with those experiencing it now, especially the poor guy trying to sleep. I can personally attest to how frustrating it really is.

- As an environmental scientist, I do have some observations that I’d like to share.

- Both locations are over granite – and lots of it.

- Both locations (Jersey, I only suspect), given the geological nature of granite, have deep watercourses/aquifers in the proximity.

- Granite often contains high amounts of quartz.

- Water flowing over a surface causes friction.

- Quartz has the capacity for discharge of piezo-electric current (think cigarette lighters) – static discharge through the granite generated by said friction, perhaps?

The noise, if it’s the same, will be rarely heard during daylight hours, and more rarely outdoors.

There is usually too much background noise and our diurnal senses filter out stuff that isn’t immediately important – it’s a survival strategy.

At night, however, we’re more attuned to it, exactly because it’s different. Again, it’s a primordial survival strategy.

It’s more like infrasound and, like the low frequency calls of the blue whale, it’s more ‘felt’ than heard, at least in the initial stages.

After a while, one develops the capacity to filter out the background and perceive it directly. Then it can be heard by just sort of ‘tuning into it’.

Sadly, once you’ve done that, it’s nigh on impossible to filter it out again, and therein lies the problem. No sleep.

I consoled myself by choosing to believe that it was simply the heartbeat of Mother Earth, after which I slept. Soundly.

It’s not your fridge motor, different frequency altogether. It is unlikely to be anything within the confines of your house.

However, it is likely that your house, if over said granite and if the foregoing is correct, acts like an amplifier, which is why you hear it more often indoors than out.

My house in the mountains was near, in relative terms, a geological fault. Is Jersey?

Granite is a volcanic rock. You are basically on top of an extinct volcano. That doesn’t mean lava doesn’t flow under you any more and increases the likelihood that you are over a fault, because volcanoes erupt at weak spots along faults, the lava taking the path of least resistance.

Lava also creates friction as it flows. Don’t panic, it’s likely to be several miles down, so I don’t think you’re in for the big one quite yet.

We are currently in a highly active phase of solar activity and it may be about to flip its magnetic poles, which it does every 11 years or so. Such activity is known to have some pretty bizarre effects on the Earth, particularly gravitationally – think laval tides.

I do recall a major sun storm a month or two ago that had NASA and the ESA worried because it was spinning anti-clockwise, a sure sign that a new round of activity was about to begin, which as a consequence would play havoc and possibly knock out many geostationary and orbiting satellites. Some of these satellites will be GPS, communications and the like.

With regard to the effects upon electrical equipment, I suspect that this is another phenomenon altogether.

As reported, this sounds like an electro-magnetic pulse, if so, diesel vehicles should remain unaffected.

Again, over granite, EMP should not be discounted. I never experienced this in the mountains, but the earth can pull some pretty worrying stunts.
However, remember that these effects can also be caused by solar flares.