100 REPORT OF THE CALIFORNIA EARTHQUAKE COMMISSION. 
mmn.; M,6kg.; L,76 + cm. The times on the seismogram are a, 13" 38™ 52°; b, 13" 
56" 20°: c, 14" 20" 27°: d, 15" 00™ 48°. 







EARTH’S 
AMPLITUDE, 
(a) PRELIMINARY] (b) REGULAR 
TREMORS. 

Max. AMPLITUDE, PERIOD. 

min. mm, sec. mm, 
0.0 3.5 22 0.25 



m 8. 
28 52 
16 24 





East component. . . 
Interval 


The time of the beginning is evidently too late. It is probable that the earth-amplitude 
was greater than calculated, as the large vibration lasted for a very short time. 
SOFIA, BULGARIA. 
Central Meteorological Institute. Dr. Spas Watzof, director. 
Lat. 42° 42’ N.; long. 23° 20’ E.; altitude, 550 meters; distance, 93.58° or 10,404 
km.; chord, 9,286 km.; direction, N. 24° E. 
Foundation, sands and sandy shales. 
Seismograms, sheet No. 13. 
The instruments used were Bosch-Omori horizontal pendulums, two horizontal com- 
ponents; mechanical registration on smoked paper. 
(1) North component: 7, 20.8 seconds; V, 10.1; J, 108 meters; e, 1.0; r, 2.7 mm.; 
M,10kg.; L, 74 cm. 
(2) East component: T,, 31.0 seconds; V, 10.1; J, 2,400 meters; ¢, 1.0; 7, 4.0 mm. ; 
M,10kg.; L, 74 cm. 


(a) First (b) SeconD REGULAR PRINCIPAL 
Fe are ree 
min. min. min. min. 
(1) North component 25.00 35.5 57.5 03.0 
(2) East component | _...... 36.0 : LS i | | Meneeioh ae 
Average ... 25.00 35.45 57.06 
Interval eee 12.32 23.17 44.38 








During the long waves at 14” 01.5", the north earth-amplitude was 0.48 mm. During 
the maximum movement of the pendulums the periods of vibration correspond very 
nearly to the proper periods of the pendulums; we can not therefore determine the 
earth’s movement. It is very difficult to determine the times of the first and second 
preliminary tremors accurately; nor is it clear where we should place the beginning of 
the regular waves. 
MESSINA, SICILY, ITALY. 
Instituto di Fisica terrestre e Meteorologia della R. Universita. Prof. B. G. Rizzo, 
director. 
Lat. 38° 12’ N.; long. 15° 33’ E.; altitude, 46 meters; distance, 94.67° or 10,524 km. ; 
chord, 9,368 km.; direction, N. 32° E. 
Seismograms, sheet No. 12. 
The instrument used was a Vicentini microseismograph, three components; mechanical 
registration on smoked paper. 
(1) Northeast component: T,, 2.4 seconds; V, 100; J, 143 meters; M, 106 kg.; 
L, 1.43 meters. 
(2) Northwest component: T,, 2.4 seconds; V, 100; J, 143 meters; e¢, 1.04; M, 106 
kg.; L, 1.48 meters. 
