Fig. 2

a Focal mechanism solutions for the 27 aftershocks determined in this study (lower hemisphere of the equal-area projection) with colors used to differentiate between the reverse (green), strike slip (red), and normal faulting (blue) mechanisms. A triangle diagram (Flohlich 1992) with a color scale is presented at the top right. Open circles indicate relocated hypocenters derived using the velocity model shown in the bottom right. The S-wave velocity is assumed by scaling the P-wave velocity by a factor of \(1/\sqrt 3\). b Results of the stress tensor inversion. The top panels show the principal stress axes with their 95% confidence regions plotted on the lower hemisphere stereonets. The middle panel shows the misfit angle for the data with respect to the best stress tensor determined by the stress tensor inversion. Here, the misfit angle represents the angular difference between the tangential traction predicted by the best solution and the observed slip direction on each focal mechanism. The bottom panel shows the frequency of the stress ratio ϕ, which belongs to the 95% confidence region. Inverted triangle represents the stress ratio of the best stress tensor