If we compare Mallet’s records, as he invites us to do, with the great outlines of human progress, we see that the two increase simultaneously, and we come to the conclusion that, taken as a whole, during the historical period the seismic activity of the world has been tolerably constant.
These conclusions, based on the evidence at our command, are not to be confuted. If, however, instead of considering the seismic energy of the whole world, we consider the seismic energy of particular areas, it seems reasonable to expect that in certain instances sometimes a decrease and sometimes an increase in this energy might be discovered, especially, perhaps, in areas which are highly volcanic.
In France we know that volcanic activity ceased at a period closely bordering on historical times, and it is not unlikely that seismic activity may have ceased at a corresponding time.
In a country like Japan, it is possible that in one district seismic energy may be on the increase, whilst in another upon the decrease.
In a country like England, it is probable that the seismic state is constant, and, whatever changes may be now occurring, they are taking place at so slow a rate that, even if our records of the historical period were complete, we could hardly be expected to find these changes sufficiently marked to be observable.
For purposes of reference, and also for examining the present question, the table, page 240, has been compiled. The earthquakes given are chiefly those which have been recorded in histories as being more or less destructive.
In the second column of this table will be seen the number of earthquakes which have occurred in Japan during each century, the centuries being marked in the first column. In columns 3 to 18 inclusive are given the number of earthquakes which have occurred during different centuries in the various countries and districts mentioned at the head of each column. These latter, which are taken from the writings of Mallet, are given for the sake of comparison with the Japanese earthquakes. If we commence with the seventh century in the column for Japan, we see that a great increase in the number of earthquakes, as we come towards the present time, is not so observable as it is in the other columns.
Key:
| 1 | Centuries |
| 2 | Japan |
| 3 | Scandinavia and Iceland |
| 4 | British Isles and Northern Isles |
| 5 | Spanish Peninsula |
| 6 | France, Belgium, Holland |
| 7 | Rhine Basin |
| 8 | Switzerland and Rhine Basin |
| 9 | Danube Basin |
| 10 | Italy, Sicily, Sardinia, and Malta |
| 11 | Supplemental table for Italy, Sardinia, and Malta |
| 12 | Turco-Hellenic Territory, Syria, Ægean Isles, and Levant |
| 13 | United States and Canada |
| 14 | Mexico and Central America |
| 15 | Antilles |
| 16 | Cuba |
| 17 | Chili and La Plata Basin |
| 18 | Northern Zone of Asia |
| 19 | Approximate Intensity in the Kioto District of Japan |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
I. | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
II. | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
III. | 1 | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — | — |
IV. | — | — | — | — | — | — | — | — | 6 | — | 23 | — | — | — | — | — | — | — |
V. | 1 | — | — | — | 1 | — | — | — | 5 | — | 19 | — | — | — | — | — | — | — |
VI. | 1 | — | — | — | 6 | — | — | 19 | 3 | — | 27 | — | — | — | — | — | — | — |
VII. | 12 | — | — | — | — | — | — | 1 | — | 8 | — | — | — | — | — | — | 15 | |
VIII. | 11 | — | — | — | — | — | — | 2 | 1 | 12 | — | — | — | — | — | — | 17 | |
IX. | 40 | — | — | — | 21 | — | 19 | 6 | — | 7 | — | — | — | — | — | — | 60 | |
X. | 17 | — | — | — | 2 | — | 2 | 3 | 3 | 5 | — | — | — | — | — | — | 24 | |
XI. | 20 | — | 8 | 3 | 16 | — | 9 | 7 | 5 | 18 | — | — | — | — | — | — | 28 | |
XII. | 18 | — | 11 | 4 | 12 | — | 8 | 18 | 22 | 23 | — | — | — | — | — | — | 20 | |
XIII. | 16 | 28 | 15 | 3 | 9 | — | 3 | 15 | 26 | 13 | — | — | — | — | — | — | 16 | |
XIV. | 19 | 4 | 8 | 21 | — | 18 | 20 | 51 | 8 | — | — | — | — | — | — | 25 | ||
XV. | 36 | 1 | 4 | 14 | — | 12 | 18 | 47 | 11 | — | — | — | — | — | — | 29 | ||
XVI. | 17 | 8 | 10 | 61 | 10 | 52 | 35 | 32 | 5 | 22 | — | 6 | 1 | 4 | 5 | — | 17 | |
XVII. | 26 | 14 | 10 | 91 | 29 | 120 | 31 | 121 | 9 | 53 | 10 | 7 | 16 | 4 | 9 | — | 11 | |
XVIII. | 31 | 111 | 63 | 93 | 237 | 71 | 141 | 88 | 438 | 20 | 124 | 88 | 24 | 85 | 2 | 10 | 32 | 8 |
XIX. | 27 | 113 | 110 | 85 | 211 | 81 | 173 | 145 | 390 | 88 | 194 | 51 | 30 | 145 | 50 | 170 | 57 | 8 |