1 Correction to: Pure Appl. Geophys. https://doi.org/10.1007/s00024-020-02637-3

The publication of this article unfortunately contained a mistake. There was an error in Eq. 5. The corrected equation is given below.

$$ z = \frac{{M_{1} - M_{2} }}{{\sqrt {\frac{{S_{1}^{2} }}{{n_{1} }} + \frac{{S_{2}^{2} }}{{n_{2} }}} }} $$

The original article has been corrected.