[klotz] earthquake WAVES 49 



In the above the amplitudes in millimeters have all been reduced 



to a 30^ period representing 400 mm. of the analyzer. In the analysis 



the first Pn.s, Pew were of that period, hence no change for the 



amplitude, but for all the others the amplitudes were multiplied 



respectively by 



67-8 81-3 132 118 147 ^ 144-6 



— — — and 



30 30 30 30 30 30 



the numerators indicate the whole period for the compound wave 

 under consideration. This reduction was necessary in order to make 

 the amplitudes intercomparable. To repeat, whatever the period it 

 must be photographed (enlarged), so as exactly to cover 400 mm. to 

 fit the analyzer. 



It may be observed that during the earthquake there were 

 microseisms (micros), but they were practically unrecognizable on 

 the E-W (magnetic damping) component, while on the N-S small 

 micros appear whose average period was 5!25, the variation being 

 confined to one or two-tenths of a second. 



