Basle is on a fault line, and seismologists say that a major earthquake could hit the region again at any time. In the time I've been living in Weil, several notable earth tremors have been recorded. Most times they occurred at night when I was fast asleep. The only time I actually felt something was November 2005, when there was a quake measuring 5.4 on the Richter Scale. The epicentre was in Waldkirch (D) near Freiburg but could be felt here. Windows started to shake and it was a bit scary.
Anyway, another tremor occurred at 5.50pm on Friday 8 December. However, the difference with this one was that it was "man-made". According to press reports, the epicentre was directly under the border area of northern Basle (Kleinhüningen) and Weil. It turns out that it was caused by a Deep Heat Mining project located in Basle only 100m or so from the border. There had been several more minor earth tremors in the 24 hours prior to this quake, and these have continued up until today, albeit barely detectable.
Although the quake on Friday evening only measured 3.4 on the Richter Scale, it felt worse, by all accounts, because the tremor occurred only 5 kilometres below ground - most natural tremors are a lot lower (15 to 20km). I say "by all accounts" because I was totally oblivious to it. By my reckoning, I'd just come out of work and was on a tram in the centre of Basle at that time and didn't notice a thing. A colleague said she felt a tremor earlier at around 5pm - which I also didn't notice.
Ho hum. Anyway, here is an article about it in German which I've scanned (click to enlarge):