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.
1663 Charlevoix earthquake
The estimated length of the most active portion of the CSZ was and the fault area was put at . By comparison, the 7 February 1812 New Madrid event, which was thought to have taken place on the Reelfoot fault and was the largest event in that series, had a rupture zone that was less than that of the Charlevoix earthquake and caused chimney damage at distances of more than . These things together suggest that the Charlevoix earthquake was similar in size to the largest of the New Madrid earthquakes and was at least a magnitude 6.8 event. The estimation of the earthquake's intensity was based on the condition of the soil where the damage occurred. A lower magnitude range would be preferred if the soil in the area was soft and loosely compacted and a range based on firm ground or bedrock would be proportionately higher.