Many persons have an obscure perception—a foreboding, which is to them always indicative of an approaching earthquake. They experience a feeling of anxiety and restlessness, a pressure of the breast, as if an immense weight were laid on it. A momentary shudder pervades the whole frame, or there is a sudden trembling of the limbs. I, myself, have several times experienced this foreboding, and there can scarcely be a more painful sensation. It is felt with particular severity by those who have already had the misfortune to have been exposed to the dangers of an earthquake.
I will here only briefly mention the celebrated earthquake of 1746, as all its details are fully described in many publications. The reader need scarcely be reminded that it happened on the 28th of October, the day of St. Simon and St. Jude. During the night, between ten and eleven o'clock, the earth having begun to tremble, a loud howling was heard, and, in a few minutes, Lima became a heap of ruins. The first shock was so great, that the town was almost completely destroyed by it. Of more than 3000 houses, only twenty-one remained. Still more horrible was the destruction in the harbor of Callao. The movement of the earth had scarcely been felt there, when the sea, with frightful roaring, rushed over the shore, and submerged the whole town with its inhabitants. Five thousand persons were instantly buried beneath the waves. The Spanish corvette San Fermin, which lay at anchor in the port, was thrown over the walls of the fortress. A cross still marks the place where the stern of the vessel fell. Three merchant vessels, heavily laden, suffered the same fate. The other ships which were at anchor, nineteen in number, were sunk. The number of lives sacrificed by this earthquake has not been, with perfect accuracy, recorded.[38] Humboldt, in his Cosmos, mentions that during this earthquake a noise like subterraneous thunder was heard at Truxillo, eighty-five leagues north of Callao. It was first observed a quarter of an hour after the commotion occurred at Lima, but there was no trembling of the earth. According to the old chronicle writers, the earthquake of 1630 was more disastrous.
The serious commotions which take place on the Peruvian coast appear to acquire progressively greater extension, but only in the southern and northern directions. A shock, of which Lima is the centre, though felt fifty leagues towards the north, and as far towards the south, may, nevertheless, be imperceptible in the easterly direction (towards the mountains) at the distance of ten or twelve leagues. This peculiarity is made manifest, not only by the terraqueous oscillations, but also by the undulations of the sound, which usually proceeds still further in a direction towards the south or the north.
Slight shocks are usually only local, and are not felt beyond the limits of a few square miles.
The atmospheric phenomena during and after earthquakes are very different. In general, the atmosphere is tranquil, but occasionally a stormy agitation is the harbinger of a change. I was unexpectedly overtaken by a violent commotion on the sand-flat between Chancay and Lima. The whole surface of the plain presented a kind of curling movement, and on every side small columns of sand rose, and whirled round and round. The mules stopped of their own accord, and spread out their legs as for support and to secure themselves against apprehended danger. The arieros (mule-drivers) leaped from their saddles, threw themselves on their knees beside the animals, and prayed to heaven for mercy.
The effect of earthquakes on the fertility of the soil is sometimes remarkable. Numerous observations tend to show that after violent commotions luxuriant lands often become barren wastes, and for several years produce no thriving vegetation. Several Quebradas in the province of Truxillo, formerly remarkable for their fertility in grain, were left fallow for twenty years after the earthquake of 1630, as the soil would produce nothing. Similar cases occurred at Supe, Huaura, Lima, and Yca. All kinds of grain appear to be very susceptible to the changes produced by earthquakes. Cases are recorded in which, after slight shocks, fields of maize in full bloom have withered; and in the course of a day or two the crops have perished.
The causes of the frequent earthquakes on the coast of Lima are involved in an obscurity too deep to be unveiled. That they are connected with volcanic phenomena seems probable. Lima is more than ninety leagues distant from the nearest active volcano, that of Arequipa. But the earthquakes of the Peruvian capital are uniformly independent of any state of activity in that volcano, and it is certain that the town of Arequipa, which lies at the foot of the mountain, experiences fewer earthquakes than Lima. Of the six serious earthquakes, the dates of which I have mentioned, only that of 1687 stands in connection with a decided shock in Arequipa, and an eruption of the volcano. Earthquakes are of rarer occurrence in the mountainous districts than on the coast, yet Huancavellica, Tarma, Pasco, Caramarca, have been visited by heavy shocks; and within a recent period the village Quiquijana, in the Province of Quipichanchi, Department of Cusco, suffered from a serious commotion. In a letter from an eye-witness I received the following account of it.
"In November, 1840, the earth began to move faintly back and forward, and a dull, distant, subterraneous noise continued without interruption. The first powerful shock occurred on the 23d of December. During the whole month of January, 1841, heavy thunder prevailed, but without any motion of the earth. On February 11th, we again had a smart shock, and from that day the vibrations recommenced, which, strange enough, were always most violent on Mondays and Thursdays. The subterraneous noise resounded incessantly; but it was heard only in the village; for at the distance of half a league from it all was tranquil. The heaviest shocks were felt in a circuit within the radius of three leagues. From May 21st to June 2d, all was tranquil; after the last-mentioned date the vibrations recommenced, and frequently became heavy commotions. They continued until the middle of July, 1841. From that time we have not been disturbed, and we have now returned to the ruins of our village."
The volcano of Arequipa, which is forty-five leagues distant from Quiquijana, manifested, during the whole of this time, no unusual phenomena, a circumstance which speaks forcibly against the idea of any local connection between the earthquake and the volcano.
On most men earthquakes make a powerful and extraordinary impression. The sudden surprise, often in sleep, the imminent danger, the impossibility of escape, the dull subterraneous noise, the yielding of the earth under the feet,—altogether make a formidable demand on the weakness of human nature.