380 



L. MARTIN ALASKAN EARTHQUAKES OF 1899 



of the three largest earthquakes originating at Yakutat moved outward 

 through the earth's crust and interior. The figures selected are taken 

 chiefly from circulars 1 and 2 of the Seismological Committee of the 

 British Association for the Advancement of Science. All records are 

 from Milne horizontal pendulums of the same general type, recording is 

 uniformly done, the magnification of amplitude is the same, and observa- 

 tions may, therefore, be roughly compared. All observations are reduced 

 to Greenwich mean time. 



The places of observation are shown in figure 8. The observed times 

 at the Alaskan localities are placed for convenience in the first column, 

 although not seismographic and not exactly equivalent to the commence- 

 ment of the preliminary tremors. It is recognized that the recorded 

 maxima on seismographs with little damping are largely instrumental 

 and do not correspond to the greatest movement of the earth. It should 

 be stated that these are based on old calculations, and that trained seis- 

 mologists might now determine the times and occurrences of the various 

 shocks with greater accurac}^, in view of the most recent seismological 

 studies. The main facts, however, are briefly assembled here for con- 

 venience of reference. 



Shock of September 3-4, 1899 



Place of observation. 



Commence- 

 ment of 



preliminary 

 tremors. 



Maximum. 



Amplitude in millime- 

 ters or seconds of arc. 



Total duration. 



Yakutat (Disen- 



h. m. s. 



21 40* 



23 38 



26 13 



30 14 

 30 65^ 

 33.6 

 35.0" 

 33.6 

 45 25 



40.8« 



h. tn. s. 





h. m. s. 



chantment) Bay, 

 Alaska. 

 Cape Whitshed, 









Alaska. 

 Victoria, British Co- 



35 9 



48 19 



Off paper 





lumbia. 



Toronto, Canada 



Tokio, Japan 



24 millimeters 



1.35 millimeters^ .. 



7.49 inches 



15.0 millimeters^ 



7 54 19 

 1 17 



Kew, England 



Shide, England 



San Fernando. Spain. 

 Bombay (Colaba), 



India. 

 Cordoba, Argentina. . 

 Mauritius, Indian 



1 3.0^ 

 1 1.5 

 1 7.1 

 1 18 34 



1 52.4 



1 51.5 s 



1 51.5 •! 



2 49.2 



8.17 inches 



4.66 inches 



3 19.9 



6.5 rnillimeters 



5.70 inches 



3 14.6 



Ocean. 

 Capetown, South Af- 

 rica. 



46.2 



2.5 inches 









