TIMES OF YAKUTAT BAY EARTHQUAKES 389 



Eiver; Messrs. Schrader, Gerdine, and AVitherspoon, of the U. S. Geo- 

 logical Survey, on the Koyukuk Eiver, and others. These last three 

 parties were engaged in topographic work, and their records might pos- 

 sibly be adjusted. The time observations at Skagway and other points 

 on the telegraph line should also be fairly correct. 



The times of origin in inner Yakutat Bay (Disenchantment Bay) have 

 been determined as follows: The first earthquake on September 3 was 

 recorded at Cape Whitshed,^^^ the Coast Survey camp near the Copper 

 Eiver delta, at 2.40 p. m. Allowing a correction of 25 minutes and 

 26 3-10 seconds of time for 6 degrees 21 minutes and 35 seconds of longi- 

 tude and a correction of 1 minute and 58 seconds of time for transmis- 

 sion about 220 miles, at the arbitrary rate of 3 kilometers, or a little over 

 two miles per second,^^^ we determine the time of origin of the shock of 

 Disenchantment Bay as about 3.031/2 p. m. September 3 (3h. 3m. 28is., 

 local time at Yukatat, or Oh. 21m. 40 Js. a. m., September 4, when re- 

 duced to Greenwich mean time). 



The first shock recorded on September 10 at Camp Whitshed came at 

 7.43 a. m. When this is corrected for longitude and transmission as 

 above, it is found that it would have been felt at Disenchantment Bay at 

 8.061/2 a. m. (8h. 6m. 28^8., local time at Yakutat, or 17h. 24m. 40^s., 

 September 10, in Greenwich meridian time). This is about 23 minutes 

 later than the shock shown by the seismograph records should have orig- 

 inated, and forces us to conclude that either (a) the first shaking at the 

 Coast Survey camp was mild and not recorded, because coming just at 

 or near the time of rising, or (&) that this shock was not central in Dis- 

 enchantment Bay, but originated somewhere else in tlie mountains near 

 by. The intensity of the first shock felt in the prospector's camp in 

 Disenchantment Bay is against this hypothesis, and the time record by 

 E. W. Beasley at Yakutat Village (7.40 a. m.) indicates the former to 

 have been the case. Mr. Beasley's sun time, though close, is not precise 

 enough, and we have adopted Doctor Oldham's seismograph time record 

 for the origin of this shock, as is shown on a subsequent page. 



A similar correction for longitude and transmission fixes the time of 

 origin of the heaviest shock on September 10, which was recorded at the 

 Coast Survey camp at llh. 58m. 33s. as about 12.22 p. m. (12h. 22m, 

 Is.) local time in Disenchantment Bay, or 21h. 40m. 13s. when reduced 

 to Greenwich mean time. 



The September 15th earthquake, observed at Yakutat at 7.15 a. m. 



101 Camp Whitshed, longitude 145° 54' 35" west, latitude 60° 27' 34" north; Disen- 

 chantment Bay, longitude 139° S3' 0" west, latitude 59° 58' 20" north. 

 '^'^ This may have been as great as 7 or 8 kilometers per second. 



