Earthquake
2 of the 7 encyclopedias on this shelf carry an entry for Earthquake. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a sudden movement of the earth's surface. The passage of a heavy railway train creates a vibration, differing from an earthquake chiefly in intensity. The causes of earthquakes are various. Sometimes an extensive crack forms in certain rock strata, and the rock on one side of the crack settles; or else the roof of an extensive subterranean cavity falls in. Other shocks originate in disturbances arising from an outburst of volcanic lava. It is thought that nearly all earthquake movements originate within the upper ten miles of the earth's crust, and most of them within two or three miles of the surface. The destructive influence of an earthquake shock is due rather to its extreme quickness than to the extent of vibration. It is believed that no earthquake vibration ever reaches a foot in amplitude, and that the earth's crust moves usually but a very small fraction of an inch. The nature of an earthquake shock may be illustrated by giving a table a sharp, quick, light tap with a hammer. A marble lying on the table will bound to a height of several inches, although the surface of the table cannot have vibrated, itself, more than one-ten-thousandth part of that distance. In this way a slight tremor or jar of the earth is quite sufficient to fling people out of bed, throw dishes out of a pantry, or bring stone walls tumbling down. No part of the earth's surface seems to be entirely free from earthquakes, although they appear to have been more frequent or else better observed near the seacoast. The list of recorded earthquakes now includes about 7,000. In the year 1876, for instance, there were 104. In 1755 the city of Lisbon was almost blotted out of existence by a sea wave caused by an earthquake. In 1811 an earthquake visited the Mississippi Valley. Five thousand square miles in the vicinity of New Madrid were lowered ten feet on an average. Productive farms were converted into hopeless swamps and the owners were forced to seek homes elsewhere. One of the most notable earthquakes in the United States occurred at Charleston, South Carolina , August 31, 1866. Nearly one hundred people were killed. Several million dollars' worth of property was destroyed. In 1868 the coast of Peru and Ecuador was swamped by huge waves created by an earthquake shock. They poured over the land with a depth of sixty feet. The city of San Francisco was damaged by the same series of shocks. In 1891 Japan experienced a notable earthquake. A crack was traced for a distance of forty miles. The earth and rock sank from two to twenty feet along one side of the crack. In 1897 an earthquake visited India. Myriads of fish were killed in the Ganges as though by an explosion of a dynamite cartridge. April 18, 1906, the region about San Francisco, California, was visited by the most destructive earthquake ever known in North America . The damage to public buildings in various towns of the vicinity was great. The destruction in San Francisco was simply appalling. Huge structures were shaken to the ground; water mains burst. To add to the horror fire broke out. Between earthquake and flames, eight square miles of buildings were almost entirely destroyed. The public buildings of the city, banks, hotels, an immense ferry station, and Chinatown were wrecked utterly. Two hundred thousand people were driven out of their homes. It is estimated that the loss of life reached 452 and that $200,000,000 worth of property was destroyed. Later in the same year a violent shock was felt on the coast of Chile, at Valparaiso and elsewhere. In 1908 a terrible earthquake visited southern Italy. A region about seventy five miles in diameter, including the northeastern part of Sicily and the toe of Italy, literally shuddered and fell a few feet in to the bed of the ocean. The shock was so terrific that almost all buildings within this territory were shaken to the ground. Messina and Reggio, cities rising from the water's edge, tumbled in ruins. Huge tidal waves came up, covering the debris with mud and washing thousands of fugitives out to sea. Where mud did not flow in, fires broke out. In a few hours' time the homes of 200,000 people in these two cities alone were either buried out of sight, or converted into ashes. The greater number of the inhabitants never escaped from the ruins. In many of the small towns half of the people met their death. The catastrophe was so extensive and the loss of life so great that no accurate report will ever be possible, but it is estimated that 200,000 people lost their lives. The following is a partial list of the notable earthquakes: NOTABLE EARTHQUAKES. Place Year Lost Lives Catania, Sicily . . . . . 1137 15,000 Syria . . . . . 1158 20,000 Cilicia . . . . . 1268 60,000 Naples . . . . . 1456 40,000 Lisbon . . . . . 1626 30,000 Ragusa. . . . ...1667 5,000 Schamaki. . . . ...1672 80,000 Port Royal, Jamaica . . . . . 1692 3,000 Sicily . . . . . .1693 100,000 Aquila, Italy . . . . . 1703 5,000 Jeddo (Tokio) . . . . . 1703 200,000 Abruzzi, Italy . . . . . 1706 15,000 Algiers . . . . . 1716 20,000 Palermo . . . . . .1726 6,000 China . . . . . .1731 100,000 Naples . . . . . 1732 1,900 Lima and Callao . . . . . 1746 18,000 Grand Cairo . . . . . 1754 40,000 Kaschan, Persia . . . . . 1755 40,000 Lisbon . . . . . 1755 50,000 Fez, Morocco . . . . . 1755 12,000 Syria . . . . . .1759 20,000 Martinique . . . . . 1767 1,600 Tauris . . . . . ..1780 45,000 Calabria . . . . . 1783 25,000 Bolivia . . . . . .1797 40,000 Naples . . . . . 1805 6,000 Kutch, India . . . . . 1819 2,000 Aleppo . . . . . 1822 20,000 Murcia, Spain . . . . . .1828 6,000 Canton, China . . . . . .1830 6,000 Calabria . . . . . .1835 1,000 Martinique . . . . . .1839 700 Cape Haytien, S. D . . . . . .1842 5,000 Point-a-Pitre, Gaudeloupe . . . . . 1843 5,000 Great Sanger . . . . . ..1856 3,000 Calabria, Italy . . . . . .1857 10,000 Quito . . . . . .1859 5,000 Erzeroum, Asia Minor . . . . . ..1859 6,000 Mendoza, South America . . . . . .1861 7,000 Manila . . . . . ..1863 1,000 Mitylene . . . . . .1867 1,000 Peru and Ecuador . . . . . .1867 25,000 Santander, Colombia . . . . . 1875 14,000 Scio . . . . . .1882 4,000 Cashmere . . . . . .1885 3,000 The Riviera . . . . . .1887 2,300 Yunnan, China . . . . . .1888 4,000 Valparaiso, Chile . . . . . .1906 1,500 San Francisco . . . . . .1906 452 Kingston, Jamaica . . . . . .1907 1,100 Sicily and Calabria . . . . . .1908 200,000 Total . . . . . 1,392,552
Collier's New Encyclopedia (1921)
the term applied to any tremor or vibration of the ground produced by subterranean causes. Many earthquakes are so gentle as to pass almost unrecognized, others excite general alarm without causing damage, while some spread destruction over wide areas. Probably no part of the earth's surface is wholly free from vibration, but destructive earthquakes are confined to comparatively limited regions. The almost universal succession of phenomena recorded in the case of notable earthquakes is first a trembling or vibration, next a severe shock, or several in quick succession and then a vibration which gradually but rapidly becomes insensible, In most cases each shock lasts only a few seconds, but the vibrations that follow may be continued for days, weeks, or even months. Noises of various kinds usually precede, accompany, or succeed an earthquake. Some of these have seemed to those who have heard them to resemble the howling of a storm, the growling of thunder, the clanking and clashing of iron chains, the rumbling of heavy wagons along a road, or the shattering of enormous masses of glass. Such noises are transmitted through the ground, the sea, or the air. Some earthquakes are not attended by subterranean sounds. At the time of the terrible shock which destroyed Riobamba in Ecuador on Feb. 4, 1797, a complete silence reigned. Subterranean sounds may be heard without any earth-tremor being perceived. Earthquakes are felt either as vertical shocks, from below upward, as horizontal or lateral shocks, or as undulatory movements. At the time of the great earthquake of Riobamba, the bodies of many of the inhabitants were projected across the river and fell upon La Culla, a hill more than 300 feet high. During the Calabrian earthquake of 1783, the undulatory movement was well marked by the motion of the trees, which swayed to and fro, their branches touching the ground. The same appearance was noted at New Madrid, Mo., during the earthquake of 1811-1812, where the trees bent as the earth-waves passed under them, immediatly afterward recovering their position. Observations of this kind have led physicists to the belief that an earthquake is a wave or true undulation of the crust. The wave produced by the original impulse travels outward in all directions from the "focal cavity," or "centrum," in successive spherical shells. The point or area on the surface of the ground directly above the "origin" or centrum, is called the "epicentrum"; it is at this point that the shock is usually felt as a vertical stroke coming from below upward. As we recede from this point, the direction of motion becomes more and more nearly horizontal, and also gradually decreases in intensity till it becomes insensible. Away from the epicentrum, the earth-wave at every point comes up obliquely from belowthe radial lines along which an earthquake is propagated from the centrum being called "wave-paths." The direction of motion is also influenced by the configuration or varying topographic features of the disturbed district. Most earthquakes occur during the cold months or in winter, at which time barometric fluctuations are most numerous. Among memorable earthquakes may be noted that of Lisbon, Nov. 1, 1755, destroying 60,000 lives, which left the city in a heap of ruins, and was felt from the Madeiras to Great Britain; and that which destroyed Aleppo in 1822. Within the United States only five great earthquakes are known to have occurred since the first settlement. The earliest occurred in the year 1755, in Massachusetts, which, though very forcible, was much less so than the other four, but the information about it is scanty. The second, the most energetic of all, was that of New Madrid, Mo., in 1811, folowed by many forcible shocks in subsequent months and years. The third was in the Inyo Valley of California in 1868; and the fourth at Charleston in 1886, which was from 107 to 120 kilometers deep and was felt at a distance of 1,000 miles. The fifth was the San Francisco earthquake of 1906, given below. The severe and destructive earthquakes since the Christian era are as follows: A. D. 79. Destruction of Herculaneum and Pompeii. Destruction of life very great, including Pliny the Elder. A. D. 526. Around the Mediterranean. Estimated fatality, 120,000 people. Dec. 18, 1631. Naples. Fatality, 3,000 people. June 7, 1692. Port Royal. Fatality, 3,000 people. A. D. 1693. Sicily. Destruction of Catania, 300 villages and 60,000 people. Oct. 28, 1724. Lima and Callao. 18,000 people destroyed. Nov. 1, 1755. Lisbon. Fatality, 60,000. It was felt over a twelfth of the earth's surface. Feb. 5, 1783. Calabria generally. 30,000 people. Feb. 4, 1797. Riobamba, Quito, Cuzca. 40,000 people. March 26, 1812. Caracas. More than 20,000 people. Jan. 11, 1839. Martinique. 300 people. Aug. 13, 1868. Peru and Ecuador. Especially at Arica, 70,000 people destroyed and $300,- 000,000 worth of property. April 3, 1880. Chios. 14,000 dwellings and 3,541 people. July 28, 1883. Ischia. 2,400 people. Aug. 27, 1883. The Krakatoa destruction was peculiarly volcanic, not seismic. It destroyed about 35,000 people by tidal Aug. 1, 1886. Charleston earthquake described above. Oct. 28, 1891. Central Japan (Owari-Mino). Destroyed 7,000 people, 200,000 dwellings, and $22,500,000 worth of property. Feb., 1902. Caucasus. 4,000 people. May 8, 1902. Guatemala. Was very fatal, but numbers unknown. It was simultaneous with the outbreak of Mt. Pelée on Martinique which destroyed St. Pierre and was fatal to 20,000 people. April 18, 1906. San Francisco Bay. Destroyed San Francisco and Santa Rosa, uncounted buildings, about 800 lives and more than (est.) $300,000,000 worth of property. Dec. 28, 1908. Messina. Destroyed the city and caused the death of 200,000 people, the worst earthquake disaster in history. May 5, 1910. Cartage, Costa Rica, destroyed. Oct. 11, 1918. Porto Rico, loss of 150 lives and property valued at $1,000,000.