RELATION TO OTHER ALASKAN EARTHQUAKES 401 



installed by the U. S. Coast and Geodetic Survey at Sitka, and on April 

 29, 1904, a Bosch-Omori seismograph, so that in the future the earth- 

 quake records from Alaska will be fairly complete. 



In the preceding list the earthquakes reported by Grewingk, Perret, 

 Dall, Petroff, and Becker in 1788, 1843, 1847, 1853, 1857, 1861, 1866, 

 1867, 1868, and 1880 are doubtless tectonic. Some may have been world- 

 shaking. The others are doubtless largely volcanic and merely local. 



Other tectonic shocks in Alaska which were probably world-shaking, 

 like these in Yakutat Bay in 1899, and which have not previously been 

 described, are mentioned below. There were no volcanic phenomena of 

 Mount Wrangell or the Aleutian volcanoes at these times. 



The Chugach earthquake of October 9, 1900, was felt between 2 and 3 

 a. m. in the Chugach Mountains and all about the Gulf of Alaska from 

 Yakutat Bay to Kodiak Island. The minimum area disturbed was about 

 121,000 square miles on the land. The seismograph stations at Victoria 

 and Toronto recognized its Alaskan origin, and instruments throughout 

 the world recorded it.^^^ The seismograph record was referred to by 

 Prof. John Milne,^*<* and seismograms at Laibach, Austria,^*^ and Tokio, 

 Japan,^*2 iig^e been published. The latter is reproduced in this article 

 as the upper seismogram in plate 30. 



The Lynn Canal earthquake of September 24, 1907, was felt at Skag- 

 way at 4.02 a. m., and at Sitka at 3.59%, where the TJ. S. Coast and 

 Geodetic Survey seismograph recorded it. 



The Prince William Sound earthquake of February 14, 1908, was felt 

 at Valdez about 1.25 a. m. ; also throughout Prince William Sound and 

 eastward to Controller Bay. Two submarine cables in Yaldez fiord were 

 broken by faulting in 600 to 700 feet of water. Seismographs recorded 

 this shock at Sitka, Victoria, Toronto, Baltimore, etcetera. 



The Controller Bay earthquake of May 14, 1908, occurred at 11 p. m., 

 and was sensible along the Alaskan coast from Seward to Sitka. Seis- 

 mographs recorded it at Sitka, Victoria, Toronto, Baltimore, Chelten- 

 ham, Washington, Porto Eico, the Hawaiian Islands, and doubtless else- 

 where. Other Alaskan earthquakes are mentioned in the following list. 



The place of observation was not usually, of course, the origin of the 

 earthquake, and it is not known how many of these shocks are volcanic 

 and how many tectonic. Many of the places referred to here are shown 

 on figure 8. 



"» Selsmologlcal Committee of the British Association for the Advancement of Sci- 

 ence, circular 3. 1901, pp. 63, 65, 69, 73; 74, 77, 85, 87, 89. 



"» Nature, vol. Ixv. 1902, p. 203. 



i« Beitras-en zur Geophysik. Ersranzunarsband. I. 1902, tafel v, fi.ar. 13. 



1^ Publications of Earthquake Investigation Committee in foreign languages, no. 21, 

 1905, fig. 51. 



