Japan is perhaps as unstable an area as anywhere exists on the earth, and the records of its earthquakes are more complete than in any other country. The number of destructive earthquakes recorded there in the last fifteen hundred years is 223. Since the beginning of the seventeenth century the records are fairly perfect, and it is found that since then a destructive earthquake has occurred somewhere in the Japanese islands nearly every two and a half years. For the lighter shocks systematic observation has become necessary, and the Japanese, with that development of the scientific spirit which is so remarkable an accompaniment of their progress during the last generation, have organised an Earthquake Recording Service—a Seismological Bureau—at which such conspicuous meteorologists as Mr. John Milne and Dr. Knott have worked, and which has produced great seismologists among the Japanese themselves. As many of our readers are aware, the earth is hardly ever still; it trembles continually like a boiling kettle, though not for the same reasons; and the delicate instruments for measuring earthquakes, which are called seismometers, show continual earth tremors or earth shivers. Since 1888 the earthquakes of all intensities recorded in Japan give a yearly average of 1447 shocks, or a daily average of four. Until the great earthquake of 1891, the greatest shocks within the memory of living men were those of 1854-5.
The earthquake of October 28th, 1891, shook an area of 243,000 square miles, or more than three-fifths of the entire area of Japan, though the greatest damage was done on the Mino-Owari Plain, a broad expanse of country occupied by rice fields and surrounded by mountains. Without the least warning the blow came, and in the first shock 20,000 buildings fell, 7000 people were killed and 17,000 were injured. Innumerable fissures great and small appeared all over the plain, and the houses in the thickly packed villages fell like packs of cards. The plain is one of Japan's great gardens, and supported almost 1000 people to the square mile. Villages were thereabout continuous, and a narrow lane of unusual destruction could be traced through them for twenty miles. After the first shock there were numerous smaller ones, and during the next five months no fewer than 256 shocks were recorded in all. Among the more remarkable effects of the earthquake was the actual shifting of the country. Along a crack many miles in length the plain after the earthquake was some feet lower on one side than on the other. Reservoirs and swamps were formed, as well as sand pits and mud craters. The most conspicuous effect, however, from a geological standpoint was the shifting and distortion of the strata.
Photo, G. C. Niven
The Curious Eruption of Mount Asama, Japan
Mount Asama is nearly 8000 feet high, and the crater is nearly a mile across, and has a depth of about 1000 feet. Steam is being continually discharged. The above display was photographed from about 8 miles distance. The discharge was about 1½ miles high, and shot up to that height in some ninety seconds. The evident inference is either that water is being forced out of the rocks by volcanic action, or that the eruptions are of the nature of steam explosions caused by water which comes in contact with molten rock.
A few years later, on the 26th and 27th August, 1896, occurred the remarkable Icelandic earthquake, which affected a triangular plateau, bordered by high mountains, including Mount Hecla and other well-known volcanoes, in the south-western portion of the island. During the shocks the earth's surface was thrown into waves, so that neither man nor cattle could stand. Persons who were lying on the ground near a cliff were by the shock thrown bodily over the edge. A high hill in the plain is described as shaken "like a dog coming out of the water," and a thick mantle of loose soil which had covered it was afterwards found distributed in heaps about its base. The surface of the plain was scarred by open fissures or by rock walls which had been caused by the earth's rising on one side of a fissure. One of the fissures was nine miles and another seven miles in length. The mountains round the plains were riven by clefts, and many landslips occurred. As we have mentioned elsewhere, a new geyser was formed, throwing up water to an enormous height, but soon spending its early force; and many geysers and springs were violently disturbed.
An earthquake of a very different kind occurred the next year in the province of Assam, India (June 12th, 1897). Unlike the Icelandic earthquake, almost the whole damage was here the result of the first shock. Everything was destroyed within the first fifteen seconds of the earthquake, and the heavy shocks had all passed before two and a half minutes had elapsed. In this brief space of time an area of 1,750,000 square miles had been shaken and 150,000 square miles laid in ruins. A member of the Geological Survey of India, who was in the town of Shillong, says that a rumbling sound like near thunder preceded the shocks by a second or so and increased in loudness, so that when masonry began to fall the noise and rattle of the falling stones were hardly to be perceived. Unable to stand on his feet, this observer sat down on the ground, and not only felt but saw the ground thrown into violent waves as if "composed of soft jelly." These waves seemed to run along the ground. When the shocks had passed all the masonry houses in Shillong had been levelled to the ground, and over each hung a cloud of pink plaster particles and dust. Some of the shocks seem to have occurred with a kind of twist, and stone monuments were given the appearance of corkscrews. There were left many fissures and depressions in the ground, and the rivers and lakes and streams were greatly affected. Thirty new lakes were formed; along the great Brahmaputra River rolled a great wave ten feet high. One great rent in the geological strata at the earth's surface was twelve miles long. Important changes of level of great blocks of country were clearly shown by the alterations in the aspect of the landscape. Ranges of hills which before had not been visible from certain points now came into view for the first time, while others had disappeared. Though the most destructive shock was that felt during the first few seconds, there were others which followed, lasting for nearly a week afterwards. This earthquake is of special interest, because it was the first one which was registered on the earthquake instruments set up in Europe. Since that date these instruments have been set up all over the world, and, as we say elsewhere, a great earthquake is now usually recorded on the seismometers and seismographic instruments set up in observatories stationed thousands of miles away.
All of our readers will recollect the Jamaica earthquake which occurred comparatively recently. Port Kingston, in Jamaica, has had its share of earthquake disasters. In the year 1692 Port Royal, the then chief city, was destroyed, and in rebuilding it the Jamaicans moved it across the harbour, because the old town site was largely submerged beneath the sea. It was a recurrence of the settlement of the ground which in part produced the earthquake of January 14th, 1907. There were slight shocks preceding the earthquake, and subterranean rumblings. The chief damage was done before thirty-five seconds had gone by, and of course the catastrophe was greater because the shocks were felt in the neighbourhood of a city. Considered by itself the earthquake was not of the order of "great" earthquakes, but many of the effects were most curious. A statue of Queen Victoria on a pedestal was partly turned round; a series of steep terraces was formed by the side of the harbour; a small spring was converted into a stream eight feet wide; and, as we all know, very great destruction was inflicted on life and property. Soundings which have since then been made in the harbour show that its depth has greatly increased in some parts, in one instance by not less than twenty-seven feet. The greatest depression occurred near Port Royal (the old city), where a hundred yards or more of the ground was submerged by water varying from eight to twenty-five feet in depth.
Proceeding northwards from the Antilles to North America, we come to other famous areas of earthquake disturbance. In 1811 and 1812 there were earthquakes along the lower lands of the great Mississippi River, which were felt throughout the whole of the eastern portion of the United States and as far west as exploration had gone. At New Madrid, which appears to have been near the centre of the disturbance, "subterranean thunder" appears to have been heard frequently for many years preceding the earthquake, though it had ceased for nearly a year. About two o'clock in the morning of December 16th, 1811, there came a severe shock accompanied by a noise which was like near thunder, and a few minutes afterwards the air was filled with sulphurous vapour. People thought that the end of the world had come. Light shocks were felt till sunrise; and then one more violent than the first occurred. But this was not the end. For three months the shocks went on, and in that time no fewer than 1874 shocks were recorded, eight of them great ones. The shock of January 23rd, though as violent as any that preceded it, was surpassed by the so-called "hard shock," which came at about four o'clock in the afternoon of February 7th. It was accompanied by a discharge of sulphurous vapour in the atmosphere, and an unusual darkness which added greatly to the terror of the people.