Recent seismological research has focused on processes other than pure shear failure (double-couple) as an alternative mechanism for some types of seismic events. This has been stimulated by what appears to be anomalous focal mecha nisms observed for several earthquakes of possible volcanic nature in the 1980 Mammoth Lakes, California sequence (JULIAN and SIPKIN, 1985; SIPKIN, 1986). Although studies have concentrated on earthquakes associated with magmatic processes, possible non-double-couple seismic failure has been observed, but not widely known, in cases of mine seismicity in the past...
Recent seismological research has focused on processes other than pure shear failure (double-couple) as an alternative mechanism for some types of sei...