IS THERE ANY EVIDENCE OF NORMAL-DISTRIBUTIONS OF EQ MAGNITUDES

The Gutenberg-Richter relation, which means that the number of earthquakes within a given magnitude interval is an exponential function of the magnitude, is considered almost as a law in seismology. In many cases the relation is not very evident but only for relatively narrow magnitude intervals. It is more like a rule that a dual behaviour exists. Further the frequency-magnitude diagrams are often so scattered that it is difficult to get any clear pattern and by using cumulated frequencies we have a great smoothing of the data, which increases the linearity of the logarithmic number-magnitude behaviour. In the present paper we have as an example studied three selected subregions of the Fennoscandian area, principally comprising the following regions: southwestern Norway, northern Norway, northeastern Sweden and northern Finland. We have found that the log-M relationship may be interpreted as a normal distribution of magnitudes as well as the generally assumed exponential one.