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.
1959 Hebgen Lake earthquake
Although magnitude estimates for the 1959 earthquake vary (the United States Geological Survey recorded the quake at both 7.3 and 7.5, now calculated by the ISC as 7.2 ) the 1959 earthquake is comparable to the 1906 San Francisco earthquake as one of the strongest earthquakes in North America, behind the 1964 magnitude 9.2 Good Friday earthquake in Alaska. The 1959 earthquake is also the most severe earthquake in the Rocky Mountain area of the United States along with the 6.9 magnitude earthquake which struck Idaho in 1983. The landslide caused by this quake was the largest since an earthquake in Wyoming in 1925 caused a landslide amounting to of rock and debris that left 28 people dead. The death toll from the quake was also the highest since the 1925 earthquake and most recent for the Northwestern United States since an earthquake in 1927 that left seven people dead. The 1959 earthquake was also the most damaging earthquake to occur in Montana since the 1935–36 earthquakes that left four people dead. The Hebgen Lake area also experienced earthquakes again in 1964, 1974, 1977 and 1985.