The mystery of the regular explosions

This page was last modified on 17 March 2002.

A sunny spring morning in March 1999; crisp air and deep blue sky; the concrete campus buildings of the [University of Kent at Canterbury] looking almost agreeable in the bright sunshine. One distracted student gets waylaid with something rather more fascinating to him than Part I Computer Science project-work…

As told to ukc.misc, the local newsgroup.

Subject: Mystery solved: the regular explosions
Date: 17 Mar 1999 17:42:53 +0000

This morning at 10 o'clock I was sitting in a quiet room in Keynes next to an open north-facing window, and kept hearing shockwaves that sounded like faint explosions, occurring every minute or few; I'd noticed these casually whilst walking around campus from time to time, but thought they were nothing.

Wondering what I might be hearing, I asked a friend to sit and listen; he missed hearing the first, and on hearing the next he claimed it was someone moving around upstairs. I didn't think so, having heard the noises on campus, so we opened the window and sat right by it. Sure enough, we could actually sense the shockwave and noticed the glass tremble; I suggested it might be quarrying activity somewhere (although I don't know of any quarries in the district).

Out of curiosity, I followed the second-hand of a watch and was further intrigued when one explosion happened exactly two minutes after the first: for the next one, I jokingly said (carefully timing my words),

“I could be wrong but I'm expecting the next one round … about … Now!”

Kaboom-rumble!!

Talk about a result… we had a very good idea of the direction they were coming from (about 20 degrees west of grid north on the OS map) so, unable to contain my curiosity, I took my bike and set out to Blean crossroads (where Tyler Hill Road comes out), as this was directly along a line from Keynes towards the direction of the sound. Throughout the past hour, I had heard the explosions at precisely 20 seconds past each odd minute in the hour, so I only had to stop for an instant to listen for the boom.

At Blean the sound had not changed direction, and I continued almost to Whitstable, where I turned off down a minor road near Clapham Hill; there I could plot exactly the direction because of a distant aerial on the hilltop — and the plot showed that the sound was in just the same direction (I could instead have ridden towards Faversham and done some triangulation!). The sounds were noticeably louder, less muffled and of course had advanced to being at five seconds past the odd minutes — but a bit of inaccuracy seemed to be creeping in at the source.

Thinking I must be about to go down into Whitstable to see an army exercise in the Bay, I continued to Seasalter and Whitstable but the sounds appeared to cease altogether after I left the higher ground. Thinking that whatever it was had finished for the day, I climbed the hill to the new dual carriageway, moved away from the traffic noise and stop for a listen: two minutes, three minutes, then “Kaboom-rumble!” once more, bang on schedule! It was considerably louder but obviously not very nearby, so it must be out to sea somewhere. I finally grasped the nettle and asked an old gent tending his front garden, who cheerfully provided the answer.

It's a military installation on the far side of the Thames Estuary at Shoeburyness where the Maplin Sands, when exposed at low tide, extend five miles offshore: they've been exploding things there “about four days in seven” for fifty years, apparently, and some of it is testing, and some of it is disposing of land-mines.

So that's the explanation for that little mystery; does anyone have any more information about the Installation there or what exactly is going on?

A [map] showing the relevant area can be found at [Streetmap].