Induced seismicity in Basel
The largest event prompted concern from local residents. The six borehole seismometers installed near the Basel injection well to monitor the natural background seismicity and the geothermal stimulation recorded more than 13,500 potential events connected with the geothermal project, from which 3,124 were of sufficient quality to permit [hypocenter] determinations in the period 2–12 December 2006, which spanned the main stimulation and the decline in the event rate. During the post-stimulation period from 13 December 2006 onward, a further 350 locatable events were detected up to 2 May 2007, by which time events were occurring sporadically at around one per day. In all, locations for more than 3,500 events were determined.
1185 East Midlands earthquake
The earthquake of 15 April 1185 in the region of East Midlands was one of the largest and most damaging earthquakes the British Isles had ever encountered. The magnitude has been estimated at around 5 . Some think the epicentre of the earthquake was close to Nottingham in East Midlands. The epicentre has also been suggested to be in or around Lincolnshire. However, it could possibly be anywhere from Dogger Bank to the East Midlands. Some references talk of the earthquake happening somewhere offshore in the North Sea east of northern England; its effects may have been felt as far away as Norway.