CHAPTER XXIX

SOME OTHER NOTABLE EARTHQUAKES

It would, of course, be impossible within the limits of this book to attempt a description of all the remarkable earthquakes in the annals of science; but before leaving this part of the theme a brief account of a few more among the many may be worth while.

Jamaica, one of the West Indian Islands, about ninety miles south of Cuba, suffered a very destructive earthquake in 1692. During this earthquake the ground was agitated like the waves of the sea. These movements were so violent that numerous fissures were made in the ground, as many as 300 being formed at the same time, rapidly opening and closing. Many of the inhabitants were swallowed up in these fissures. In some cases, however, their bodies were afterward thrown out of the fissures, along with quantities of water.

The Jamaican earthquake was characterized by marked sinkings of the ground. At the city of Port Royal, which was then the capital, many houses on the harbor side sank in from twenty-four to forty-eight feet of water. As in the case of the earthquake at Cutch, many of these houses were left standing, the chimney tops of some being seen above the water, with their foundations and other parts apparently uninjured, and some of them were standing at a date as late as 1780. At a little later date, 1793, they were mostly ruins.

During the Jamaican quake a tract of land containing at least 1,000 acres near the town was sunk, and a wave of the sea rolled over it. This wave is said by Lyell to have carried a frigate over the roofs of the houses and left it stranded on one roof. When the wave rolled back to the sea, the weight of the frigate made it fall through the roof.

Perhaps one of the most remarkable things about the Jamaican earthquake was the swallowing up of several plantations, which disappeared, together with all their inhabitants, their former place becoming a lake. But the lake soon disappeared, leaving a mass of sand and gravel which obliterated any least sign that dwellings and trees had once adorned the spot.

The forces developed during this earthquake were sufficiently powerful to make several rents in the Blue Mountains, and the shock of blows on the waters of the sea killed fish by the hundred thousands so that the silver shine of their dead bodies stretched for miles and was beheld for days "on the face of the deep."

Portions of the world that have been frequently visited by mighty earthquakes, are the coasts of Chile. On the 24th of May, 1751, a part of the Chilian coast near the ancient town of Concepcion, sometimes called Penco, was destroyed by an earthquake, and the powerful earthquake waves that afterwards rushed in from the sea. So complete was this destruction that the ancient harbor was rendered useless and the people had to build another town about ten miles from the coast, so as to be beyond the reach of earthquake waves from the sea.

Another great earthquake occurred on the coast of Chile on the 19th of November, 1822. This shock was felt simultaneously over a distance of 1,200 miles from north to south. It reached its greatest intensity about 100 miles north of Valparaiso. This earthquake caused a rising of the coast to a height of from three to five feet. From careful examinations it appears that the area over which a permanent elevation of the country took place must have been equal to 100,000 square miles, an area equal to about half of the area of France, and five-sixths that of Great Britain and Ireland.

"If we suppose," says Dana, "the elevation to have been only three feet on an average, it will be seen that the mass of rock added to the continent of America by the movement, or, in other words, the mass previously below the level of the sea, and after the shock, permanently above it, must have contained fifty-seven cubic miles in bulk; which would be sufficient to form a conical mountain two miles high (or about as high as Etna) with a circumference at the base of nearly thirty-three miles.... Assuming the Great Pyramid of Egypt, if solid, to weigh in accordance with the estimate before given 6,000,000 tons, we may state that the rock added to the continent by the Chilian earthquake would have equalled more than 100,000 pyramids.

"But it must always be borne in mind that the weight of rock here alluded to constituted but an insignificant part of the whole amount which the volcanic forces had to overcome. The thickness of rock between the surface of Chile and the subterranean foci of volcanic action may be many miles or leagues deep. Say that the thickness was only two miles, even then the mass which changed place and rose three feet, being 200,000 cubic miles in volume, must have exceeded in weight 363,000,000 pyramids."

The shocks of this earthquake continued from the time of its occurrence, on November 19th, 1822, to the end of September, 1823, and even then there were scarcely two days that passed without a shock.

On the 20th of February, 1835, the same part of the world was in the throes of an earthquake that was felt nearly 1,000 miles from north to south, or from near the town of Concepcion to the Isle of Chiloe, and from east to west a distance of about 500 miles, from Mendoza to the island of Juan Fernandez, which you probably know better as Robinson Crusoe's Island. By this earthquake the new town of Concepcion and several other towns were partly destroyed.

There were the same phenomena connected with great sea waves that are common in earthquakes of this character. Both this and the preceding earthquakes probably began on the bed of the ocean at some distance from the coast; for, in the last earthquake, the sea retired from the Bay of Concepcion and vessels were grounded that had been anchored in seven fathoms of water. Shortly afterwards waves from sixteen to twenty feet in height rushed in from the ocean and swept over the land.

It is interesting in this connection to note that the volcanoes of the Chilian Andes were in an unusual state of activity before, during, and after the earthquake.

Another characteristic of this quake was the great number of severe shocks. Between the day of the first great shock; i. e., on February 20th, 1835, and March 4th, there were more than 300 severe shocks.

In this as in the preceding quake a notable elevation of the land near the coast occurred, amounting to from four to five feet, and a part of the bed of the ocean near the coast was raised permanently above the level of the sea.

In the description of the explosive eruption of Krakatoa in 1883, the fact was noted that the island of Java is very frequently visited by earthquakes. Here a terribly severe earthquake occurred on the 5th of January, 1699. There were no less than 208 shocks of great intensity. Considerable property in the city of Batavia was destroyed, and a neighboring river, that has its head waters by a volcano near the city, ran high and muddy and brought down multitudes of fishes that had been killed, together with many buffaloes, tigers, rhinoceroses, deer, and other wild beasts. Seven hills bordering on the river sank down, damming up the streams of the region and thereby causing wide destruction from floods.

During portions of the years 1811 and 1812 an earthquake occurred in the United States, in the Mississippi Valley near the town of New Madrid, Missouri, at the mouth of the Ohio River. These shocks continued almost incessantly for several months, and were accompanied by a sinking of the ground over large areas. This depressed area, known in the neighborhood as _The Sunk Country_, extended along the course of the White Water River and its tributaries for a distance of about eighty miles from north to south, and several miles from east to west. Most of it was converted into a marshy lake characterized by thousands of submerged trees. The area was covered for the greater part with water to a depth of about three to four feet.

As the earthquake shocks continued at intervals for several months there was an ample opportunity for studying the peculiarities of the earth waves. The ground rose and fell like large waves in the sea, and after the crest of the waves had reached great heights, the ground burst, and threw large quantities of water, sand, and earth into the air.

Throughout the disturbed district there were numerous depressions known as _sink-holes_, or irregularly shaped pits, varying from ten to thirty yards across, and having a depth of about twenty feet. These were formed by the forcible ejection of large quantities of water mixed with sand.

New Zealand has been subject to earthquake shocks for a long time, the years 1826, 1841, 1843, 1848, and 1855 being especially marked by such visitations. It is a characteristic of the New Zealand earthquakes that they have produced a marked change in the coast line. This was particularly the case with those of 1848 and 1855.

The 23d of January, 1855, an earthquake occurred that was most violent in the narrowest part of Cook's Strait, a body of water separating the two principal islands that constitute New Zealand; or, as they are called, the North Island and the South Island. These shocks were felt at sea by ships 150 miles from the coast. The entire area shaken, including the water, has been estimated at three times the area of the British Isles. In the vicinity of the southern shores of the North Island a tract of land having an area of 4,600 square miles is believed to have been permanently raised from one to nine feet.

The earthquakes in New Zealand are evidently of the tectonic type. During that of 1848 a rent or fissure was formed, which, though but eighteen inches in average width, yet extended for a distance of sixty miles in a direction parallel to one of the mountain chains.

On the 31st of August, 1886, an earthquake of considerable intensity occurred in the United States in the neighborhood of the city of Charleston, South Carolina. The details of this earthquake were carefully studied by Major Dutton of the U. S. A., and published in the Ninth Annual Report of the United States Geological Survey of 1888.

Charleston is situated on a narrow tongue of land between the Ashley and the Cooper Rivers, about seven miles from the Atlantic Ocean. There are in this area numerous creeks connected with the drainage of these rivers. As the city limits extended, the creeks were filled in, forming "made land," all buildings or structures erected on this land being supported by pilings.

It appears that the point at which the earthquakes started was situated sixteen or seventeen miles from Charleston.

The earthquake shock affected a large area of the United States. Fig. 49 shows curved lines called isoseismal connecting places, having the same degree of seismic intensity. This map shows that these isoseimals are marked by figures or numbers from two to ten. These numbers are the numbers of the Rossi-Forel earthquake scale. They indicate varying degrees of intensity, beginning from the least intense shock which is marked as two and ending with the severest shock marked as ten. There is one degree not marked on this map, the least, called the micro-seismic shock.

The shocks then increase in intensity as follows: II. Extremely feeble shocks; III. Very feeble shocks; IV. Feeble shocks; V. Shocks of moderate intensity; VI. Fairly strong shocks; VII. Strong shocks; VIII. Very strong shocks; IX. Extremely strong shocks; X. Shocks of extreme intensity.

The meaning of the map presented in the accompanying figure will now become more apparent in several ways. That portion numbered ten, denoting where shocks of greatest intensity have been experienced, clearly indicates the region just above the point where the earthquake originated.

Beyond this is a region marked nine where the earthquake shock has decreased in intensity to the next figure on the Rossi-Forel scale, and then to eight and a half, seven, six, five, four, three, and two.

The Charleston earthquake damaged property to a considerable extent; for, although comparatively few buildings were completely destroyed, a considerable number were partially injured, and many, not thrown down by the shock, had to be torn down in order to insure public safety. The loss of life, fortunately, was comparatively small. During this earthquake a number of openings called _craterlets_ were made in the ground by the forcible ejection of large quantities of water and sand.

The empire of Japan is another part of the world particularly subject to great as well as frequent earthquake shocks. Although Japan is also especially noted for its volcanic activity, its earthquakes are almost entirely of the tectonic type, or are due to the slipping of the land at faults in the earth's crust. Most of these quakes occur on the bed of the ocean on the sides of a steep slope that extends down to a very deep part of the Pacific known as the _Tuscarora Deep_.

On the 28th of October, 1891, Japan was visited by a great quake, generally known as the Mino-Owaro earthquake, from the name of the two provinces of Mino and Owaro in which it occurred.

This earthquake is correctly regarded as one of the most severe in Japanese records. Originating, as it did, in a densely populated section, it caused a great loss of life and property. The deaths reached about 7,000, while the number of houses entirely destroyed reached about 80,000 and those partly destroyed nearly 200,000. The total area markedly affected reached 250,000 square kilometres, while the area sensibly affected reached 900,000 square kilometres, or a little more than one-half the Empire.

The place at which this earthquake started was situated, not as usual on the bed of the ocean, but on the surface of the land. The first shock was the strongest and wrought the greatest havoc. Besides the loss of life and property, the damage to the system of dikes or levees on the river where it passed through the delta plain near the river's mouth was heavy, and singular in some of its features. In one case, near the city of Nagoya, on the Bay near the southern coast of Niphon, one of these levees was lifted and shifted bodily more than sixty feet from its original position.

That this quake was of the tectonic type was evident from the great fault that was formed. According to Davison this fault was seventy miles in length and in places had a breadth of from two to five feet. It extended from east to west, crossing the entire width of the island.

Another great earthquake was that which hit northeastern Bengal and Assam in India on the 12th of June, 1897. According to the India Geological Survey, by whom a careful examination of the effects produced by this quake was made, it was, perhaps, the greatest quake that ever happened, not even excepting the Lisbon earthquake.

The place where the quake started appears to have been of unusual size and irregularity of outline. Its southern boundary was almost in the shape of a straight line extending from east to west about 200 miles, and covering a total area of nearly 6,000 square miles. Over all this vast area the intensity of the shock was exceedingly severe. The total area perceptibly shaken by the quake was about equal to 1,750,000 square miles.

That this quake was of the tectonic type became evident, when several faults were found in the ground afterwards. Some of these extended twelve miles, with a breadth at places as great as thirty feet.

Valparaiso, or, as the name means, Vale of Paradise, the second largest city of Chile and its chief seaport, lies about ninety miles east of Santiago, the capital, with which it is connected by a railroad.

This beautiful sea city is built at the base of a cluster of hills about 1,600 feet above sea level. On August 16th, 1906, it was visited by an earthquake. There were two distinct shocks. Contrary to general rule it was not the first, but the second shock that did the most damage, coming about ten minutes after the first. As you will see from the above date the earthquake of Valparaiso occurred shortly after the catastrophe of San Francisco. In a general way, its coming was predicted by Dr. G. F. Becker of the United States Geological Survey, on April 19th, 1906, one day after the San Francisco disaster. Becker published an article in the "New York Tribune," in which he argued that the severe shock at San Francisco, having occurred on one part of the earthquake region extending around the Pacific, would probably soon affect other portions of this region along the Pacific coast line of this hemisphere.

As at San Francisco fierce fires immediately started in the ruins of the houses, but the Valparaisans were more fortunate in having a water supply available.

There were very many shocks following the first two of this earthquake. Indeed, during August 16th, 17th, 18th, and 19th, no less than 380 were noted.

Santiago, situated at the foot of the Andes, was also considerably damaged by the same earthquake. Estimates, probably conservative, put the total of dead in both cities at 1,000 and the number of people rendered homeless temporarily, at 100,000.