Date of Award


Degree Type


Degree Name

Master of Science


Dr. Robert Shcherbakov


The occurrence of supershear ruptures implies unique pre- and post-seismic stress con­ ditions on and around the host fault segment leading to off-fault aftershocks. This increases seismic hazard even at very large distances away from the main fault. This thesis tries to ascertain whether this leads to anomalous statistical behaviour of the aftershock sequences produced by these events. The aftershock sequences of the known supershear events are studied and, for each sequence, the statistical features of the aftershocks in the supershear zone are compared with those of the rest of the aftershocks. It is observed that the ¿»-value is always higher in the supershear zone, the largest aftershock magnitude is smaller than that expected according to Bath’s law and that there is no systematic trend in the spatial distribu­ tion of the exponent of the modified Omori law. It is further proposed that these statistical features are a consequence of the off-fault distribution of aftershocks and that the ¿»-value anomaly is due to the dependence of the ¿»-value on material strength.



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