Energy Technologies: How They Work and Their Induced Seismicity Potential - Induced Seismicity Potential in Energy Technologies - page 55

mitigate the occurrence of further events—injection was stopped in the early morning hours of December 8
after approximately 11,500 m 3 (~3 million gallons) of water were injected (Deichmann and Giardini, 2009)
and after the recording of M 2.6 and M 2.7 seismic events. During this injection period, more than 10,500
seismic events were recorded (Häring et al., 2008). While the well was shut in (operations terminated), seismic
activity continued, so it was decided to “bleed off” the pressure (reduce pressure through controlled release).
On December 8, an earthquake of M 3.4 occurred in Basel and was clearly felt by the local population. This
was followed by three more events greater than M 3.0. The project, operated by Geopower Basel AG as a
partnership of both public and private companies, was immediately suspended and then ultimately abandoned
almost 3 years later following further study and risk evaluation after these seismic events. However, increased
seismicity activity over historical levels is likely to continue for 7 to 20 years based on Bachmann et al.'s (2009)
model for induced seismicity.
December 2006 - February 2008
Figure 2 Seismic events and wellhead pressure at Basel. SOURCE: Kraft et al. (2009).