88 



KNOWLEDGE 



[May 2, 1892. 



THE GREAT EARTHQUAKE IN JAPAN OF 1891. 



By the Eev. H. N. Hutchinson, B.A., F.G.S. 



LAST year the Japanese empire was visited by one of 

 those great catastrophes that every now and then 

 cause widespread destruction to life and property. 

 The country, as everyone knows, is a land of 

 Earthquakes. It is calculated that at least live 

 hundred shocks occur every twelve months. Japanese 

 people talk of Earthquakes from day to day just as we, in 

 England, discuss the weather, and hardly a day passes 

 without some perceptible shaking. 



Our present knowledge of Earthquake phenomena is 

 largely due to the valuable labours of Prof. Milne in Japan. 

 We propose, in the present paper, to give some slight 

 account of the great Earthquake of last year as described 

 in an interesting and beautifully illustrated book' by 

 Professors Milne and Burton, containing twenty-nine large 

 photographs, mostly taken by one of the authors for the 

 Japanese University. These have been very artistically 

 reproduced and printed by a mechanical process by Mr. K. 

 Ogawa, so that they are as permanent as the paper they 

 are printed on (which is itself a product of the Earthquake 

 district, being manufactured only in Echizeu). These 

 illustrations will be found most helpful by anyone wishing 

 to study the effects and phenomena of Earthquakes, for they 

 give a far better idea than any amount of verbal description, 

 and for the time being one almost seems to be transported 

 to the district in question, and to be studying the effects 

 on the spot. 



The Nagoya-Gifu Plain, which has been so sadly devas- 

 tated, is one of Japan's great gardens. It occupies the centre 

 of the empire, and is in the prefectures of Aichi and Gifu. 

 To give some idea of the destructiveness of this Earth- 

 quake it may be mentioned that the most severely shaken 

 district, in many portions of which the destruction of 

 buildings and engineering works was complete, extends 

 over 4200 square miles. Brick buildings were affected 

 over a still larger area, viz. : as far as Tokyo to the east, 

 and Kobe to the west ; but the disturbance made itself 

 felt over an area of 92,000 square miles. The authors 

 estimate that, if the Japanese islands presented a larger 

 surface of land, the effects might have spread over an area 

 of 400,000 square miles. They tell us that a disturbance 

 occurred in the Mino mountains, and at once an area 

 greater than that of the empire of Japan became a sea 

 of waves, the movements being magnified on the surface 

 of the soft alluvial plains. In Tokyo, more than 200 

 miles from the centre of the disturbance, the ground 

 moved in long easy undulations, producing in some persons 

 dizziness and nausea, the movements being not unlike 

 what we might expect upon a raft rising and falling on an 

 ocean swell. But near to this centre the waves were short 

 and rapid ; whole cities were overturned, the ground was 

 rent, small " mud volcanoes " were created, and the 

 strongest of engmeering structures were ruined. The loss 

 of life was fearful ; about 10,000 persons were killed, 

 15,000 were wounded, 100,000 houses were levelled with 

 the plain, whilst almost every building in the inner seismic 

 region was shattered. From these effects it is concluded 

 that the earth-movements in Mino at the time of the great 

 Earthquake were at least equal to any movements recorded 

 in the annals of seismology. 



* " The Great Earthquake in Japan, 1891," b_y Jolm Milne, F.R.S., 

 Professor of Mining and Geology, Imperial University of Japan, and 

 W. K. Burton, C.E., Professor of Sanitary Engineering. Imperial 

 University of Japan. Published by Lane, Crawford & Co., Yokohama, 

 Japan ; Agent for this country, Edward Stanford, Cocks])ur Street, 

 Charing Cross, 



In speaking of the possible causes of Earthquakes, the 

 authors point out that in the Nagoya-Gifu district there 

 are neither volcanoes nor volcanic rocks ; the plain is a bed 

 of alluvium lying in a basin of pala-ozoic hills, and it 

 was in these hills that the disturbance began. Hence it 

 does not appear that this was one of those cases in which 

 an Earthquake is connected with volcanic action, as many 

 undoubtedly are. Rather it suggests a huge, internal, 

 sudden jar, and possibly a slip or displacement, producing 

 what is known to geologists as a " fault." In the general 

 process of mountain formation, by which strata are com- 

 pressed, contorted, and elevated above the level at which 

 they were originally formed in lakes, seas, or estuaries, 

 fractures must from time to time take place, when the 

 internal strain becomes greater than they can bear. 

 Geologists have sought the cause of such movements as 

 these, by which mountain ranges are upheaved, in the 

 secular cooling of the earth, whereby the outer layers 

 cooling and contracting less rapidly than those down 

 below, tend to be left unsupported, so that in settling down, 

 they are thrown into folds, much in the same way as the 

 skin of a dried apple is wrinkled. But it must be admitted 

 that at present the subject of earth movements of all kinds 

 — the slow movements producing elevation and depression 

 of lands, or the sudden movements whereby the surface of 

 the earth is shaken — is still involved in much obscurity. 



Leaving these questions, let us turn our attention to the 

 actual effects produced by the Great Earthquake in Japan 

 last year. The greatest destruction has taken place along 

 and near the river banks ; the reason of this seems to be 

 that, being unsupported on one side, the momentum of the 

 shock has shot them forward much in the same way that 

 the last of a series of railway waggons is shot forward 

 when a locomotive bumps against the other end. Our 

 illustration^ shows the kind of destruction which has 

 occurred along the banks of the Biwajima Eiver for a 

 distance of several miles. Innumerable longitudinal clefts 

 occur, of all widths up to about two feet ; also the inner 

 half of the embankment has slid down towards the river 

 to some extent, sometimes to a number of feet, measured 

 vertically. At one place the embankment is entirely gone 

 for a couple of hundred feet or so, and here a very strange 

 thing has happened : a large bamboo grove and a few pines 

 just at the back have been pushed sixty feet back, and yet 

 the bamboos and trees remain upright ! It will be seen 

 that one thatched roof has fallen intact. The longitudinal 

 cracks are well seen in the illustration. 



The road from Nagoya to Gifu is a series of nllages, or 

 rather was, a nearly continuous street of more than twenty- 

 five miles in length ; now, except in a few cases, it is 

 simply a narrow lane between two long heaps of debris 

 that were once houses. The recent Earthquake teaches us 

 that wooden houses, built on European models, have 

 suffered less than ordinary Japanese dwellings, which have 

 heavy roofs, no diagonal bracing, and light supports. No 

 wonder that the heavy roof brings the whole structure down. 



The disturbance seems to have been greatest in the 

 famous Neo Valley, where the ground has been both 

 elevated and depressed. The people say that the moun- 

 tains themselves have been depressed, so that from certain 

 points, hills, formerly invisible, can now be seen. 



Earthquakes frequently cause landslips, and in this case 

 we find that landslips were taking place for several days 

 after. People who witnessed them were greatly impressed 

 by the roaring noise and vibration. It is probable that 

 the sounds are transmitted through the earth. 



t Our Illustration is copied from the Photograph of Profs. Milne 

 and Burton, by the kind permission of Messrs. Stanford. 



