In Fig. 4(a), the polarity of ground velocity was found to be reversed. Therefore Fig. 4 should read as follows:

Fig. 4
figure 1

(a) Ground velocity record of another artificial earthquake during another blasting experiment at another site and (b) electric field record, corresponding to the groune velocity. E x and E y denote the northward and the eastward components of electric field, respectively. (c) Absolute values of transfer function derived from the observed ground velocity and the observed electric field.

It should be noted that the discussion and concluding remarks are not subject to correction.