Show EARTH ZONE WAS VERY SMAll Richfield Shocks Not Recorded by Seismograph at Uni University University of Utah According to Professor Fred C Pack of the University ot of Utah any slight dis disturbance disturbance In the fault block which ex extends extends tends across the middle and southeastern section of the state might produce a con alterable seismic disturbance In those dis districts without affecting In any great measure other sections ThIs would ex explain explain plain the tact fact that there was a recent heavy earthquake In the vicinity ot of RIch RIchfIeld Richfield fIeld Utah which not only did not make Itself felt outside Its own Immediate zone but produced no record on the seismograph seismograph graph at University This fault block Professor Protessor Pack states extends across the state from Mantl Manti to the Colorado line and down through the southeastern part of at the state and across the Colorado river Into Arizona The na nature nature ture ot of the formation of at the earth throughout thIs section Is such that there might be disturbances In the lay layers ers era constituting the earth there without there being any disturbance anywhere else In the state A slide ot of one of the blocks of the fault for tor example might shake the earth In that vicinity and pro produce duos duce no effect at all anywhere else In Inthe inthe the state This Is shown by the fact that the re recent recent cent earthquake at Richfield left no of official record on the Instruments at the University The disturbances In the country about the northern part of Great Sale lake were recorded only slightly by bythe bythe the Instruments at the University and In several ot of the cases were not recorded at all Just what should be the explanation explanation nation ot of this particular phenomenon Professor Pack does not to explain How Vibrations Travel It Is a well weli known tact fact however that earth vibrations travel better In some kinds of formation than In others and Professor Protessor Pack cited the familiar exam example plo of pounding upon a steel rail with witha a hammer which produced vibrations for fora a long distance whereas If a piece ot of otwood wood were placed upon the rail the vi vibrations vibrations would be felt only a short dis distance distance tance These vibrations In the earth travel for fora a greater distance when the ground Is hard than they do when the ground Is of at a less firm composition It Is likely that the ground In the localities which have been affected In the recent disturb disturbances disturbances ances was such that the disturbances did not travel an any great distance The pro professor fessor stated that he could give a num number ber ot of cases In which there had been quite serious disturbances In different sections of the state where no records had been shown on the seismograph The professor said that he had received numerous reports of at a heavy disturb disturbance disturbance ance In the vicinity ot of Richfield especially ally last Sunday and there had bad been no confirmation by his Instruments This latter fact however did not affect the value of at the reports from the places af affected affected since the formation of the earth at those points was such that vibrations not necessarily travel to other places |