164 REPORT— 1890. 
much more disturbed than the western side. If we take a map of Japan, 
and commence at the north-eastern end of Yezo, and proceed southwards 
along the Pacific Coast, the districts most disturbed are, with but three 
exceptions, the extremities of all the peninsulas jutting out into the ocean 
-—a fact which, when we remember that many of these peninsulas repre- 
sent earth-foldings which may be continued, or are being continued, 
beneath the ocean, is of considerable significance. The exceptions 
referred to are the earthquakes of the alluvial plain round, and to the 
north of Tokio—where at least 80 shocks were recorded—the earthquakes 
on the alluvial plain at the head of the Bay of Owari, and the earth- 
quakes round the flat shores of the Bay of Tosa, on the south side of 
Shikoku. 
During 1887 the Shinano earthquakes, which in 1886 were 19 in 
number, decreased to 5, whilst the Echigo disturbances decreased from 
31 to 10. These localities are inland, and are respectively at distances of 
60 miles N.E. of Tokio and 100 miles north of Tokio. 
As in previous years, in Central Japan, where there are many earth- 
quakes and many volcanoes, the earthquakes, or at least the majority of 
them, did not come from the volcanoes. In the Kii peninsula, where 
there are no volcanoes, there have been many earthquakes ; but there are 
also districts, as for example the southern extremity of Kiushiu, where 
there have been a fair number of earthquakes, where it is possible that 
such disturbances may be directly connected with the proximity of vol- 
canoes. On the whole, however, there is no reason to consider that the 
majority of earthquakes are in any way connected with voleanoes. The 
approximate origin of shocks which have been recorded in 1886 and 
1887 is given in the following table, from which we see, at least for 1887, 
that the greater number of earthquakes, especially those of any extent, 
have chiefly originated along the coast or beneath the sea. 
Table of distribution of earthquake origins relative to sea and land. 
— Total | Large |Moderate| Small 
Earthquakes which occurred a) 1886 228 15 50 163 
neath the sea or along the coast. 1887 302 36 76 190 
Earthquakes which occurred in- 1886 244 11 70 163 
land c P . : { 1887 181 14 34 133 
1886 472 26 120 326 
fotat mie {] 1887 | 483 50 | 110 | 398 
More (+) 
Tess) peOE UBT Wea +11 +24 —10 -—3 
AREAS SHAKEN BY HARTHQUAKES. 
Probably the best method we have at our command for measuring — 
the seismic activity of any region, rather than considering it proportional 
to the number of disturbances which occur, is to measure it by the area 
of land which has been shaken. As has been pointed out in the Report 
for 1888, this method of measuring intensity is only approximate, but 
still it is very much better than methods used by previous investigators. 
The unit is one square ri or 5°95 square miles. 
