Page images
PDF
EPUB
[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][ocr errors][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][subsumed][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small]

The barometer readings are given as the number of millimetres above 700.

The barometrical change is the difference in the readings on successive days taken at 2 P.M.

=

The numbers representing barometric gradient are the number of millimetres on the weather map (where 1 mm. 6 geo. miles), which correspond to a difference in pressure of 5 mm. Where a number is omitted it means that the barometrical pressure has been fairly uniform over Central Japan.

Temperature is indicated in the Centigrade scale and rain in milli

metres.

To show the state of the weather the following signs have been usedd=cloudy, c=clear, r=rain, f=fine, fg=fog, and s=snow.

The relative humidity is in percentages, 100 being saturation.
Tension is expressed in millimetres of mercury.

The force of waves is recorded at 2, 6, and 10 A.M., and at 2, 6, and 10 P.M. at the various lighthouses round the coast. The scale employed is as follows:-0-calm, 1 smooth, 2=moderate, 3=rough, 4=high, 5=very high, 6=tremendous. In the tables the mean value for the above hours is given for Jogashima, 33 miles south from Tokio, and for Inuboye, 53 miles east of Tokio.

6) Earthquakes recorded by Horizontal Pendulums in Tokio, October 31, 1894, to February 7, 1895.

To obtain Greenwich mean time, subtract nine hours. The instrument which recorded a given shock is indicated by its letter. The numbers in brackets indicate the width in millimetres of the displacement as shown upon the photographic trace. The times given are obtained by a rough measurement of the diagrams. For several of these disturbances it would have been desirable to have made the time observations more accurate, but owing to the loss of my notebooks by fire, this is now impossible.

[merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][ocr errors][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][ocr errors][ocr errors][merged small][ocr errors][ocr errors][ocr errors][merged small][merged small][ocr errors][merged small][merged small][ocr errors][ocr errors][merged small][ocr errors][merged small]
[merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][ocr errors][merged small][merged small][merged small][merged small][merged small][merged small]

11 20.0

22.0 to 24.0. A. Several small disturbances.

19 1.0, 3.0, 4.30 to 6.0, 7.0 and 8.0, each about (5). A.

20 2.0, several; 2.45, 4.0, 4.30 and 9.0, each (2) to (4). A.

21 1.0. 2.0, 4.0 and 5.0. A. All doubtful.

23 3.0 (15), local origin; and up to 9.0, four shocks each (2). A. 30 18.0 (20).

19.0 (5).

[blocks in formation]

18 3.0 and 6.0 (3), introduction to a tremor storm. (Local origin..) 11.0, large earthquake. A. (Local origin.)

[blocks in formation]

One of the most interesting of these disturbances is that which was recorded at three stations, at about 18 hours, on October 27. The origin of this was near to the Antipodes of Japan, in the Argentine Republic. In the shaken district Dr. E. von Rebeur-Paschwitz tells me that the mean velocity of progagation was about 1.2 km. per sec. Mr. C. Davison tells me that it reached Europe to be recorded at Rome with a mean velocity for the large motion, of 3.17 km. per sec., the preliminary vibrations having a velocity of 10.38 km. per. sec. These latter movements reached Charkow and Nicolaiew with velocities of 11:47 and 9.47 km. per sec. If the record J for Japan can be assumed to be approximately correct, then the movements recorded in Japan, if they were propagated over the surface of the earth, reached that country with a mean velocity of 19 km. per sec. The figure is reduced from the record of K.

[merged small][merged small][merged small][merged small][merged small][merged small][ocr errors]

III.-DESCRIPTION OF A CATALOGUE OF 8,331 EARTHQUAKES RECORDED IN JAPAN BETWEEN JANUARY 1885 AND DECEMBER 1892.

(a) History of the Catalogues.

In order to determine the number of shocks which are felt per year in Japan, and to obtain some general idea as to their distribution, in 1880, with the assistance of Mr. Toshiwo Nakano, the present writer communicated with residents in all the principal towns of the Empire, asking them to furnish information about the seismic activity, both past and present, of the districts in which they resided. An examination of the replies which were received led to the conclusion that on the average there were three or four shocks per day, or for Japan alone there were as many shocks per year as Professor Heim had calculated for the whole globe ('Trans. Seis. Society,' vol. iv. p. 30). In the following year, in order to determine the extent of country which was shaken by a given shock, bundles of postcards were sent to very many towns and villages within a range of about 100 miles of Tokio, with a request that every week one of these cards should be returned with a statement of the earthquakes which had been felt. The result of these communications showed that nearly all the shakings which disturbed Tokio came from the east and north, and seldom passed beyond the mountain ranges to the west and south. These facts having been established, the barricade of postcards was extended northwards until it reached Sapporo, which is about 450 miles north from Tokio. With this system, between October 1881 and October 1883, 387 earthquakes were recorded, for each of which a map was drawn showing They may have passed through the earth with a velocity of 13 km. per second.

the area which had been shaken and the approximate centre from which each disturbance had originated. To render the observations more complete, one or two watches were given to telegraph operators (a few of the more enthusiastic observers provided themselves with good time-keepers), and seismographs were sent to the following stations:

[blocks in formation]

From these observations it was definitely shown that the greater number of earthquakes had their origin along the seaboard or beneath the ocean, that the volcanic and mountainous regions of Japan are singularly free from shakings, and that the country might be divided into seismic regions (Trans. Seis. Soc.,' vol. vii. Part II.). The establishment of these and other important results in 1884 led the Imperial Meteorological Department, then under the direction of Mr. Arai Ikunosuke, to undertake the continuation and extension of investigations, the labour and expense attending which were altogether too great to be borne by an individual. On the retirement of Mr. Arai the work was continued by Mr. K. Kobayashi, the present Director of the Bureau, and it is to his kindness that I am indebted for access to the vast amount of material that has been accumulated. The observing stations from which this material is being derived, and which for the last two years has been pouring in at a rate too fast for analysis, are as follows:

Gunyakusho (district offices). (As several of the smaller of
these are controlled by their larger neighbours, postcards
and letters are only forwarded from 527)

Kencho (offices at the capitals of provinces)
Fu (large cities), Tokio, Kyoto, and Osaka

Light-houses

Light-ships

Meteorological Observatories (of these 39 have instruments).

Total number of reporting stations

[ocr errors]

804

43

3

63

52

968

The information derived from these stations, which are distributed over the Empire, an area of 140,000 square miles, is from time to time supplemented by records obtained from stations under the control of the Imperial University and those of private observers.

When an earthquake is felt, according to the area over which it has extended, the number of postcards, letters, and diagrams which may be received at the central station vary between three or four and several hundreds. From the catalogue it will be seen that between 1885 and 1892 more than 8,331 shocks have been recorded, and for each of these a separate map has been drawn. To draw these maps, which has been entirely the work of the Meteorological Department, it is possible that 80,000 to 100,000 documents were examined. For reducing this bulky mass of matter into the comparatively small and accessible form in which it has been published, my thanks are due to Mr. M. Suzuki, a former

« PreviousContinue »