66 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION, 
VICTORIA, BRITISH COLUMBIA. 
Meteorological Office. R. F. Stupart, F. R.S.C., director; E. Baynes Reed, superin- 
tendent. 
Lat. 48° 27’ N.; long. 123° 22’ W.; altitude, not much above sea-level; distance, 
10.41° or 1,157 km.; chord, 1,155 km.; direction, N. 20° W. 
Foundation, solid rock. 
Seismograms, sheet No. 1. 
The instrument used was a Milne horizontal pendulum, east component; photographic 
registration. 7, 15 seconds; V, 6.1; J, 330 meters; angular displacement, 1 mm. 
=/().76" 5.250 o9m.9) 9, 15.6 cm: 
Kast component: First preliminary tremors, 14.2"; second preliminary tremors, 14.7™; 
maximum, 17.1"; amplitude, 17+ mm. 
There seems to have been a reinforcement of the motion at 15.2™, and at 16.1™ the 
motion was strong enough to join the records from opposite sides of the seismogram ; 
that is, the amplitude of the pointer exceeded 17 mm.; this continued with slight inter- 
ruptions for 11 minutes, and then diminished with many irregularities. If Victoria 
recorded only the violent shock, the velocity of propagation would have been 1,155/104 
= 11.1 km./sec., which is far too great; we must therefore believe that the beginning of 
the record refers to the earlier and lighter motion that began at 5" 11™ 58° at a point 
25 km. further from Victoria. The velocity would then be 1,181/134 = 8.8 km. /sec., 
which is a little but not much larger than might be expected. The beginning of the 
strong motion on the seismogram, coming a half minute after the beginning of the record, 
occurs too early for the long waves from the earlier disturbance, and too early even for 
the second preliminary tremors. It must represent the first preliminary tremors of the 
violent shock, whose velocity would then be 1,155/134 =8.6 km./sec. We thus get two 
records of the velocity of the first preliminary tremors; which agree very well when we 
consider the difficulty of determining the exact point on the seismogram where the 
movements begin, and the further difficulty of reading the corresponding time as near as 
a tenth of a minute. The strong motion, beginning at 16.1", would correspond in time to 
the arrival of the second preliminary tremors of the earlier shock, but as this shock was 
not felt in Sitka it does not seem possible that it could have made so great a record in 
Victoria, even tho the latter recorded especially the transverse vibrations and the former 
the longitudinal. The remainder of the record is complicated by the overlapping of 
vibrations coming apparently from different parts of the fault-plane. 
SITKA, ALASKA. 
Magnetic Station of U.S. Coast and Geodetic Survey. O.H. Tittmann, superintendent ; 
Dr. H. M. W. Edmonds, magnetic observer. 
Lat. 57° 03’ N.; long. 185° 20’ W.; altitude, 15 meters; distance, 20.72° or 2,303 km.; 
chord, 2,291 km.; direction, N. 19° W. 
Foundation, directly on solid rock. 
Seismograms, sheet No. 11. 
The instrument was a Bosch-Omori horizontal pendulum, north component ; mechanical 
registration on smoked paper. T,,14 seconds; V,10; J,.490 meters; e€, 1.0; r, 1.0 mm.; 
M,10kg.; L, 75 cm. 




First EESEIMING RE ARCOM ERROR ARE an lao Wines INS 
; Ms Be m & m 8. m8 mM. 8 mm, 
North component 17. 02 21 06 22 32 | 238 30to030 20 65 + 
Interval. . 4 34 8 38 10 04 


