Earthquake Size Estimates and Negative Earthquake Magnitudes - Induced Seismicity Potential in Energy Technologies - page 192

M
FIGURE E.2 Graph shows b values for two different microearthquake populations during a hydraulic
fracture treatment. The b values vary from about 1 for reactivated tectonic microseismic events and 2
for microseismicity associated with the hydraulic fracture injection. The hydraulic fracture microseismic
magnitudes are typically very small (less than M 0), hence the lack of larger microseismic events on this b
value example. SOURCE: From Wessels et al. (2011).