TY  - JOUR
ID  - epos1510
UR  - http://dx.doi.org/10.1007/s000240050187
IS  - 1
A1  - Talebi, Shahrair
A1  - Boone, Tom J.
N2  - We analyze source parameters of microseismic events (M < ? 1) associated with high flow-rate water injections in a shale formation at a depth of 220 m. Two types of events were observed several hundred impulsive events with clear P- and S-wave arrivals, and continuous emissions with peaked spectra detected well into the experiment. For a representative collection of impulsive events, an ?2 model provided satisfactory fits to displacement spectra corrected for attenuation, and average quality factors of 34 and 15 were obtained for P and S waves. P-wave first motion analysis and E S ?/E P ratios indicated the existence of a non-double-couple component in some events, particularly early in the experiment. A clear difference was observed for estimates of stress release parameters as non-double-couple events had smaller stress drops and apparent stresses. The seismic efficiency of double-couple and non-double-couple events was limited to 0.9% and 0.05% respectively, with average values being 0.25% and 0.02%. A comparison of our results with those reported for a similar magnitude range in a hard-rock formation indicates considerably smaller estimates of stress drop and apparent stress in our case while seismic efficiencies are comparable.
VL  - 153
TI  - Source Parameters of Injection-induced Microseismicity
AV  - none
EP  - 130
Y1  - 1998/11//
PB  - Springer Verlag
JF  - Pure and Applied Geophysics
KW  - Water injection
KW  -  microseismic events
KW  -  source parameters.
SN  - 0033-4553
SP  - 113
ER  -