2008 Kasatochi Earthquake Swarm

Overall, there is a strong causative relation between the behavior of the seismic swarm and the eruption episodes. Due to seismic network limitations in the region (all stations are in a linear array along the island arc), determining accurate locations of the Kasatochi seismicity became a challenge.

The locations have much larger uncertainties in the N-S direction than in the E-W direction, and overall are poorly constrained. Moment tensor inversions of the 12 largest events resulted in solutions with large non-double-couple components. The consistent orientation of the moment tensors, combined with rupture lengths of a typical magnitude 5.8 earthquake and knowledge of the likely regional stress field, suggests the intrusion of a dike system. This dike system may extend several kilometers from the volcano in a possible orientation ranging from NNW-SSE to E-W.