ON Tin: DAHTIiyUAKi; rHEXOMENA OK JAPAN. 



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Fo'iiih Report of tL' ('outiiiltft'c, coiis'tsiuxi of .Mr. W. ETiiKitiiMii;, 

 .Mr. 'I'JIOMAS (ji{AV, (dul J'rofi'ssor .loiiN Mii^NK (lSe.crelaft/), 

 apixtiided for ihe ^ntrpusn <f lnvesli(j<Uln<i the Eartliijnuke 

 Phenomena of Japan. Drawn up by the. Secretary. 



Ui i;ix<i the last year, tlint is, IVom Juno 18S:J to the end of ^lay 1884, 

 nnlv tliirty-niiio riirtlitjnakc.s liavo boon recorded in Tokio. In llio throe 

 ])iovions years diiriiijj coiTeHpitiuling periods the number of records were 

 ".J, -u, and 28. Js'ot only have tlie shocks been few in number, but they 

 liavo also been unusually feeble. At tlie time when the greatest shocks 

 oconrrod, which was at the end of Decemher and in Januiiry, I was 

 absent from Tokio on a visit to the Takasliinia Colliery, near Nagasaki, 

 with tlie object of establishing an nndergi'ound observatory. 



AUliougli, as these remarks indieiite, my opportunities for the obser- 

 vation of earihtjnakes have been small, I am {)leased to state that J have 

 Ikou sir.gularly ibrtniiatcin obtiu'ning a series of most interesting records, 

 anil at the same time have liiid leisure to work up a portion of the nu- 

 merous observations which during the last few years have been steadily 

 accumulating. A few of the results which have been obtained liavo 

 alreaily been eomrnunicati^d to the Seiamological Society. These, together 

 with others which yet remain for publication, ai'c briefly as follows: 



Bkrmiiiafion of areas from icldrli the shakhujs so often felt in Norfh .lajnin 



emanate. 



In my report to the IJi'itish Association in 1882, I stated that 1 had 

 sent bundles of postcards to all the important towns within a radius of 

 sixty to one hundred miles of Yedo, with a request that every week one 

 of these cards should be returned to mn together with a statement of the 

 earthquakes which had been felt. Subsequently the boundary of the 

 postcard area was extended until it covered the whole of Japan north of 

 Tokio. I did not extend the area far towards the south, because 1 quickly 

 discovered that it was seldom that earthquakes originated in that direction 

 whilst disturbances travelling from the north towards the south quickly 

 died out as they reached heavy mountain ranges which in that part of the 

 country had a strike at right angles to the direction in which the die- 

 tarbances were travelling. At the end of September 188;5, after exactly 

 two yoiirs of observation, I ceased to supply my correspondents witli 

 postcards and commenced the arrangement and aimly.sis of the .accumu- 

 lated n;aterial. From rccrular observers I found that I had received 

 iibout 1,500 letters, whilst there were also a lai-ge number of others froni 

 casual correspondents. 1 also had the records of instruments placed in 

 various parts of the countiy, and a very extensive series of diagrams and 

 uotes made by myself and others in Tokio iind Yokohama. 



In the two years I refer to, in North Japim and Yezo 387 earthquakes 

 Imd been noted. Of each of these I was ensibled to draw a map showing 

 the area over which it had been felt, and to indicato approximately its 

 origin. In the determination of origins 1 Wiis gieatly assisted by the 

 records of instruments and the time obsorvaticnis which had been checked 

 by daily time signals sent by the Telegra]di Department from Tokio. 

 One hundred and twcntv-five of these maps drawn on a small scale 



1884. " n 



