374 L. MARTIN ^ALASKAN EARTHQUAKES OF 



second each. Shocks were also felt on this date at Cordova and Valdez, 

 on Prince William Sound, and at Sitka. 



On September 26 four shocks were felt at Cape AVhitshed, one of them 

 at 2.40 a. m., during a rain-storm, waking sleeping men ; one at 12h. 5m. 

 38s. p. m., lasting half a minute. There was a short shock at 2.46 p. m., 

 and another during the night. One of these earthquakes seems also to 

 have been felt at Eagle. 



On September 29 the last earthquake of the series was sensible at 

 Cape Whitshed during the night, the Coast Survey observers feeling none 

 others before they left the Copper River delta on October 23. Light 

 after-shocks were felt at Yakutat, however, all winter. '^^ R. W. Beasley 

 lists them as occurring December 14, 20, and 28, 1899 ; January 12 and 

 27, and February 16, 1900. 



• 



Seismograph Records 



study by seismologists 



As has been pointed out by Dr. G. K. Gilbert,'^^ this series of Yakutat 

 Bay earthquakes is of importance because it belongs in the rather small 

 group of adequately observed great shocks. "It ranks high in the scale 

 of energy, the position of its origin has been determined with unusual 

 precision, and its initial time is known with close approximation." More 

 than this, it is an abnormal group of shocks^^ in its departure from the 

 normal sequence of (1) prelude, (2) great shock, and (3) after-shocks. 

 This group (figure 7) perhaps had no prelude (August 27?); there 

 were at least four great shocks (September 3, 10, 10, 23) ; several other 

 important ones (September 15, 17 (?), 26), and a long series of after- 

 shocks. 



The seismograph records at Victoria, British Columbia (figure 1), 

 the station nearest to Yakutat where precise instrumental observations 

 were made, were first noticed, while the earthquakes were still in prog- 

 ress, in newspaper interviews with Mr. Napier Denison.^^ Afterwards 

 these world-shaking earthquakes were studied by experienced seismolo- 



'8 Rev. Albin Johnson : Report of Commissioner of Education for 1898-9, vol. 2, 1900, 

 p. 1402. 



■^^Preface to report on the Yakutat Bay (Alaska) earthquakes of September, 1899, by 

 B. S. Tarr and Lawrence Martin, in Professional Paper of the U. S. Geological Survey 

 (in preparation) . 



80 G. K. Gilbert : Earthquake forecasts. Science, N. S., vol. xxix, 1909, pp. 126-127. 



81 Victoria Semi-Weekly Colonist, September 21, 1899 ; same, September 28, 1899 ; 

 Chicago Times-Herald, September 25, 1899 ; New York Daily Tribune, September 25, 

 1899 ; San Francisco Examiner, September 25, 1899. 



