ON SEISMOLOGICAL INVESTIGATIONS. 51 
; Il. The Large Harthquakes of 1908. 
The distribution of origins for the large earthquakes of 1908 is very 
similar to that of 1907. The greatest activity has been at the overlap of 
districts EK and F. In the totals for districts the earthquakes for the 
BF overlap have been regarded as belonging to K and not to F. Harth- 
quake No. 1603 is included in the total for H, and Nos. 1568 and 1602 
in those for K. The correct number of District C for 1906 is 27 
and not 29 (see map and Report for 1907). 
In studying these districts it must be remembered that they merge 
_ one into the other, and cannot be regarded as so many strictly defined 
isolated elliptical areas. C, H, K, and F may, for example, be looked 
upon as districts of marked activity along a band which extends nearly 
round the world, while D, B, A, E represent areas of marked intensity 
on a band which fringes a great part of the Pacific Ocean. 
The total number of earthquakes which have occurred in 1908 on 
the east side of the Pacific is slightly greater than those which occurred 
‘in 1907. A similar increase is noted for the west side of the same ocean. 
A table published in the ‘-B. A. Reports,’ 1908, p. 63, shows that 
for the years 1899 to 1907 inclusive the greatest megaseismic activity 
has prevailed in the East Indian Archipelago, and the least on the West 
Coast of South America. If, instead of comparing the activity in the 
large districts which are indicated on the accompanying map (Plate I.) 
_ by the letters A, B, OC, &c., we compare the number of large earth- 
~ quakes which have originated during the last ten years within areas 
_ each about five degrees radius, the results arrived at are as follow :— 
Centre 120° E. 5° N. gave 75 large earthquakes. 
» 140° ER. 40°N. ,, 68 ,, As 
4 70° HE. 25° N. ,, 40 ,, ” 
» =145° W.45°N. ,, 33> ,, 5 
These figures indicate that at the present time the most pronounced 
centres of seismic activity are to be found in the centre of the Kast Indian 
chipelago and from the Kast Coast of Central Japan south-westwards 
wards Formosa. ‘The first of these is near to the junction of two 
_ pronounced lines of folding in the earth’s crust, 
__ In the Report for 1908, p. 64, reference is made to 148 after-shocks 
vhich in 1907 were recorded between January 14 and July 5, in Jamaica; 
inety-two of these appear to have been recorded in the Isle of Wight. 
he time taken for earth waves to travel from Jamaica to the Isle of 
ht, a distance of 67 degrees, would be about forty-three minutes, and 
at this interval of time subsequent to shocks in Jamaica that we find 
hickenings and sinuosities in seismograms obtained in Britain. A 
number of these records are also to be found on seismo- 
hic traces obtained at Bidston, Kew, Paisley, and Edinburgh. This 
rrence of records from different stations and the particular 
imes ai which they occur in reference to the times of origin 
f shocks in Jamaica lead us to the conclusion that com- 
tively small shocks may with suitable instruments be recorded 
at localities several thousands of miles distant from their origin. The 
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