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.
Heisei period
On 11 March 2011, Japan suffered the strongest recorded earthquake in its history, affecting places in the northeast of Honshū, including the Tokyo area. The quake's magnitude of 9.0 approached that of the severe 2004 megathrust earthquake. A tsunami with waves of up to 10 meters (32.5 feet) flooded inland areas several kilometers from shore, causing a large number of considerable fires. The epicenter of the quake lay so close to coastal villages and towns that thousands could not flee in time, despite a tsunami warning system. At the Fukushima Daiichi Nuclear Power Plant and three other nuclear power plants,serious problems occurred with the cooling systems, ultimately leading to the most serious case of radioactive contamination since the Chernobyl disaster (see Fukushima Daiichi nuclear disaster), as well as ongoing electric power shortages. Following the earthquake, for the first time, the Emperor addressed the nation in a pre-recorded television broadcast.