qu ake ▁sources , ▁called ▁the ▁Rich ter ▁scale . ▁In ▁ 1 9 3 7 , ▁he ▁returned ▁to ▁the ▁California ▁Institute ▁of ▁Technology , ▁where ▁he ▁spent ▁the ▁rest ▁of ▁his ▁career , ▁eventually ▁becoming ▁professor ▁of ▁se ism ology ▁in ▁ 1 9 5 2 . ▁ ▁Career ▁Rich ter ▁went ▁to ▁work ▁at ▁the ▁Car neg ie ▁Institution ▁of ▁Washington ▁in ▁ 1 9 2 7 ▁after ▁Robert ▁Mill ikan ▁offered ▁him ▁a ▁position ▁as ▁a ▁research ▁assistant ▁there , ▁where ▁he ▁began ▁a ▁collaboration ▁with ▁Ben o ▁G uten berg . ▁The ▁Se ism ology ▁Lab ▁at ▁the ▁California ▁Institute ▁of ▁Technology ▁wanted ▁to ▁begin ▁publishing ▁regular ▁reports ▁on ▁earth qu akes ▁in ▁southern ▁California ▁and ▁had ▁a ▁pressing ▁need ▁for ▁a ▁system ▁of ▁meas uring ▁the ▁strength ▁of ▁earth qu akes ▁for ▁these ▁reports . ▁T ogether , ▁Rich ter ▁and ▁G uten berg ▁de vised ▁the ▁scale ▁that ▁would ▁become ▁known ▁at ▁the ▁Rich ter ▁scale ▁to ▁fill ▁this ▁need , ▁based ▁on ▁meas uring ▁quant it atively ▁the ▁disp lacement ▁of ▁the ▁earth ▁by ▁se ism ic ▁waves , ▁as ▁Ki y oo ▁W ad ati ▁had ▁suggested . ▁ ▁The ▁pair ▁designed ▁a ▁se ism ograph ▁that ▁measured ▁this ▁disp lacement ▁and ▁developed ▁a ▁log arith mic ▁scale ▁to ▁measure ▁intensity . ▁The ▁name ▁" m agn itude " ▁for ▁this ▁measurement ▁came ▁from ▁Rich ter ' s ▁child hood ▁interest ▁in ▁astronom y ▁- ▁astronom ers ▁measure ▁the ▁intensity ▁of ▁stars ▁in ▁magn