EARTHQUAKES. [From the Penny Cyclopadia.]

New Zealand Spectator and Cook's Strait Guardian, Volume V, Issue 344, 18 November 1848, Page 3

EARTHQUAKES. [From the Penny Cyclopadia.]

Earthquakes are the most terrific of all natural phenomena. The solid surface of the globe is put in motion by them, and assumes an appearance which in some cases may be compared with the sea when agitated by the wind. The least dangerous of these phasnomena are those which by the Creoles of South America are called Tremhlores, a term which may be translated by tremors. The surface of the earth is put in a trembling motion, by which such objects as are not well supported are thrown to the ground, and even walls are split, but the damage does not extend farther. Life is safe, and property but slightly injured. These tremors are by far the most common kind of earthquakes, and occur in some countries of South America, especially in Chile, almost every day, at least in certain seasons. The terremotos of the Creoles, or proper earthquakes, give to the surface either horizontal oscillations, not dissimilar to the waves of an agitated sea, or they consist in violent perpendicular upliftings, so that it would seem as if repeated explosions were exerting their force against the roof of a subterraneous cavern, threatening to burst it open and blow into the air everything placed over it. By these earthquakes walls are overthrown, and fissures are produced in the ground. The latter are frequently more than a foot in width, and sometimes water gushes out of them like a fountain. Nothing makes such an 'awful impression on the senses as an "earthquake. The earth is violently convulsed, heaving up and down in a manner hardly conceivable by those who have not witnessed it. The tottering buildings, the crashing of the timbers of the roofs, and the falling oi tiles, completely distract the senses. Fear drives men from their houses ; but they do not always find safety out of doors. No person can stand without support ; people cling to one another, to trees, or to posts. Some throw themselves' on the ground ; but the motion of the earth is so violent that they are obliged to stretch out their arms,on each side to prevent themselves from being tossed over. Animals are equally alarmed. They stand with their legs spread out and their heads down, trembling violently. The air itself seems to participate in the convulsion, for the birds fly about wildly. Meanwhile the sea retires from the shore; but after a few minutes it returns in a high wave, which advances like a watery wall with incredible velocity, and covers all those tracts which are not more than fifty feet above high-

water mark. It rushes back with equal velocity. This motion of the sea is repeated as long as the shocks of the earthquake tire i violent. Vessels sailing along a coast convulsed by an earthquake feel also a motion quite different from that produced by gales or currents. The loss of life by earthquakes, is sometimes considerable. It is chiefly pro*" . duced by the falling of the buildings when the shock is so unexpected that the inhabitanis have not time to escape. In some cases the overflowing of the sea has been fatal to a great number of persons. People have also been swallowed up by the fissures caused by earthquakes. Earthquakes are generally preceded and sometimes attended by a subterraneous noise, which is compared by some to that of a very » heavy artillery waggon rolling quickly over , a stone pavement at a distance ; by others, to the echo of distant thunder in a mountainous . country. It is worthy of remark that this * noise is sometimes heard without any earfchr quake taking place, as in 1784 at Guanaxu-* . ato, in Mexico, and that it has been as audible in places situated at a considerable dis-. tance from the seat of the earthquake as in those which experienced the shocks. There are also several cases on record in which' the... earthquakes have not been attended by such ' subterraneous noise. ' > ' Considerable changes may be produced on the surface of the globe by earthquakes. '. It is said that by the earthquake of 1783 in Calabria some mountains changed their .relalative positions to one another ; but this fact is not well established. It is, however, be- . yond all doubt that the coast of Chile has,, undergone a considerable change by. earthquakes during the last fifteen years. In 1822 the coast, north of Valparaiso, to the ? extent of fifty miles, was raised nearly three feet above'its former level ; in some places the rocks on the shore were raised four feet. In 1825 the island of S. Maria (near 37° S. lat.) was upheaved nine feet, so that the southern port of this island has almost been destroyed, and the soundings round the island have diminished a fathom and a half everywhere. The single shocks of an earthquake last from a few seconds to two or three minutes. Sometimes they follow one another at short intervals. It is remarkable that generally either the first or one of the first shocks is the most violent, and that they afterwards *" gradually decrease in force. Sometimes they, return for several days, and even weeks ; and in some places, as at Copiapo, in Chile, they are of daily occurrence. Earthquakes are sometimes experienced over an immense tract of country. The last earthquake in Chile (in 1835) was felt at all places between the islaud of Chiloe (40° S. lat.) and Copiapo (27° S. lat.); consequently over thirteen degrees of latitude. It extended from the island of Juan Fernandez to the town of Mendoza, on the east side of the range of the Andes, over ten degrees of longitude. But when earthquakes extend over such an immense tract of country, some districts are always- convulsed with greater violence, and these may be considered as the centre of the earthquake. The farther a place is removed from these centres, the less violent, as a general rule, are the shocks. We know little or rather nothing, of the origin or cause of earthquakes. It may, however, be considered as certain that they are due to the same energy which produces volt canic eruptions. These eruptions are frequently preceded by earthquakes ; and whenever, in places situated near active volcanoes, it is < observed that no smoke issues from their craters, the inhabitants begin to fear the approach, of an earthquake. x^ It is not quite certain whether or not there is any connexion between the state of the atmosphere and the phenomena of earthquakes. It is not improbable that such is the case w;ish the slighter shocks, the tremlhres. , Tihey. commonly occur, or at least are by far most<_ frequent, at the time of the changes of the . seasons, in Guatemala as well as in Chile. But the more violent concussions seem to be quite independent of the seasons, and they occur both in calm and cloudless weather and in storms during rain. In some instances they have been preceded by luminous meteors. ; Ancient authors, especially ThucyduJeSj frequently mention earthquakes ; but only in general terms. Yet we learn enough from these slight notices to show that they were often equal in violence to those which, in modem times have convulsed the continent of Europe and Asia (Thucyd. 1. 101 ; ill- 89; v. 50; viii. 41.) No detailed description of an earthquake in Europe or in the old continent exists before that which, on the Ist November, 1755, almost destroyed the city ,of Lisbon. This is the most destructive earthquake which has ever occurred in Europe." The number of persons that perished by it lt is , stated to have been 30,000. In February, and March, 1783, the north-eastern part of Sicily and the southern portion of Calab.ria," were convulsed by repeated and very violent'

shocks, which overthrew the town of Messina, and killed many thousands of its inhabitants, as well as many persons in Calabria. The last considerable earthquake in Europe extended over the middle of the kingdom of Naples, and was most destructive in the districts lying along the declivities of Mount Matese. (41° 30' N. lat.) The number of persons who perished by it amounted to 5274, besides 1615 who were wounded. On the first day of the present year (1837) the countries along the eastern extremity of the Mediterranean, especially Syria, were violently agitated by an earthquake. The towns of Damascus, Acre, Tyre, and Sidon, suffered great damage, and Tiberias and Safet were entirely destroyed. - It is stated that about 6000 lives were lost. America is more subject to earthquakes than any portion of the Old Continent, but they are only strongly felt between 20° N. lat. and 40° S. lat.; and it is not the whole ■country included between these latitudes that k visited by them, but only the table-lands of the Mexican isthmus, the Andes, and the countries bordering on them, and those which «« adjacent to the Carribean Sea. Mention of earthquakes in- these countries occurs in -the Spanish historians of the Conquest ; but it would seem as if the earthquakes were less destructive formerly than in the last century. In 1717 the town of Guatemala was greatly damaged by an earthquake on the 29th of September; and on the 29th of June, 1773, 4he town was almost entirely destroyed. CaTacas was destroyed by an earthquake on the 26th of March, 1812, when upwards of 12,000 of its inhabitants were buried in the ruins ; and the same town experienced, in 1826, another earthquake, which was hardly jess destructive. Bogota experienced a very severe shock in 1827. On the' table-land of Quito violent earthquakes are frequent. In 1698, on the 20th of June, Lacatunga and Hambato were destroyed; and on the 4th of February, 1787, the town of Quito was greatly damaged, and Riobamba levelled to the ground. Not less than 40,000 persons are stated to have perished by this last earthquake on the table-land. Lima and the countries about it are likewise subject to frequent and violent earthquakes. The town of Lima was almost destroyed on the 20th of October, 1687, and again on the 28th October, 1746. In this latter catastrophe the port of Callao was inundated by the sea, and the whole population perished. Arequipa has had its share of earthquakes; but the last violent one occurred 1725. Copiapo was destroyed on the 11th of April, 1819, and again in 1823. By this last earthquake, which happened on the 19th of November, the town of Valparaiso was levelled to the ground. Santiago has suffered largely from the destructive effects of the earthquakes so frequent in Chile : on the Bth July, 1730, it sustained great damages. But no place in Chile has so frequently been destroyed as Concepcion. It was first destroyed by the united effects of repeated shocks and the inundation of the sea in 1730, and again iv the same manner in 1751. After this the town was rebuilt on another site ; but this new town and its port of Talcahuano were entirely demolished on the 20th of February, 1835. A most graphic description of this dreadful earthquake is given in the London Geographical Journal, vol. vi. p. 319, &c, to which we are much indebted for several valuable facts and remarks. The inundation of the sea during this calamity may be compared with the narrative of a similar event recorded by Thucydides (iii. 89.)