6.3 Geographical epicentre-coordinates (localisation by one seismographic station)  [ cont'd (b) ] 3/5

If one transfers these ground-displacements into a coordinate system of axes, which correspond to the four cardinal points of the compass

Fig.55: two-dimensional ground-movement-diagram

One simulates a two-dimensional movement, which comes up to the frame movement of the historical "Wiechert-Seismometer", (s. Fig. 56).