EARTHQUAKES. 121 



!!( d a very uncommon appearance, in the column of smoke proceeding from it during the Lisbon 

 curtli(|iiake; Stromholi, for the first time in the memory of man, wag quiet in 1783; and the 

 closing of tin- \. tit in Pasto was followed by the earthquake of Riobamba, in which 40,000 

 sons |.< i isli.-d.* Humboldt's seriesf commences with the formation of a new inland in the 

 A /.ores, at a spot where 40 fathoms water existed previously. In February, 1811, 'a volcano, 

 acconi|'!inir.l by violent earthquakes, burst from the sea near the west end of St. Michael's, and 

 in June following, after raging several days, and ejecting cinders and stones, the crater ap- 

 IM -iirud above the surface. Two days after, it was 160 feet high, and ultimately it rose to more 

 than 300, with a diameter of nearly 600 yards. From May, of the same year, until April, 

 1812, severe earthquake shocks were felt at St. Vincent and most of the smaller West India 

 islands in the vicinity of that usually very active volcano. The Mississippi valley earth- 

 quakes were in December, 1811, and through the winter of 1812. One occurred at Caraccas, 

 also, in December ; the city was destroyed in March, and the earth continued shaking until the 

 5th of April. Finally, on the 30th April, 1812, the volcano of St. Vincent broke out, with an 

 explosion so terrific that the shock was felt on the Apure, more than 200 miles distant, and 

 subterranean noises were heard at Caraccas at the same time. 



Mr. Darwin's series is as follows: There was a dreadful earthquake at Sabionday, near 

 Pasto, (latitude 1 15' N.,) on the 20th January, 1834. Eighty persons perished, and the 

 town of Santiago (Peru) was swallowed up. Sixty bad shocks threw down two thirds of Santa 

 Martha, about the 22d of May ; and there was a violent shake at Jamaica on the 7th September. 

 On the 20th January, 1835, the volcanoes of Osorno, Aconcagua, and Conseguina were in erup- 

 tion, and the last continued in activity during the ensuing two months. February 12th a very 

 strong earthquake was felt at sea, off the coast of Guyana ; and eight days afterwards submarine 

 explosions, off Juan Fernandez and Talcahuano, accompanied the destruction of Concepcion. 

 The coast of Chile was then permanently elevated ; and volcanoes were in continued eruption, 

 for some months subsequently, along the whole length of the Andes. November llth there 

 was another severe earthquake at Concepcion, Osorno and Corcovado being in violent action; 

 and on the 5th of December Osorno fell in with a grand explosion. J 



The disengagement of water, smoke, ashes, sulphurous vapors, and even flames, at times, 

 when earthquakes occur in regions where volcanoes do not exist, must be regarded as additional 

 proofs of the connexion of the phenomena; and the frequency and now recognised univer- 

 sality of tremors, has been supposed to point to the deep-seated molten strata as their origin. 

 At one time, those tremors which manifested themselves in alluvial formations apparently very 

 remote from igneous action, and kept the earth in vibration for months successively, as France 

 in 1808, the United States in 1811-' 13, and Asiatic Turkey in 1822, remained as exceptions 

 seemingly inexplicable. But, as the vibrations ceased in every case with the bursting out of a 

 volcano, and there was ' ' scarcely room to doubt that every active volcano is in immediate 

 communication with the whole melted matter in the interior, " the identity of the forces seems 

 apparent ; and it is now generally admitted that elastic fluids, subjected to enormous pressure 

 in the interior of the earth, are not only quite sufficient to account for these harmless trem- 

 blings, but also for those terrific explosions which devastate kingdoms. 



Although it is probable that the surface of the earth is almost always shaking at some point, 

 fortunately for mankind terrific explosions are rare. Moreover, experience has shown that 

 most of them are submarine, and so far from the habitations of man that their effects are 

 greatly modified before reaching him. That such was the case with all the great earthquakes 

 felt in Chile, except that of April 2, 1851, is evident from one concomitant, as we shall per- 

 ceive in the explanation given of them. 



* Daubony : Oil volcanoes. Second edition, 1844. t Geological Transactions, Vol. V, second seruw. 



t Personal Narrative, Vol. IX. $ Edinburgh New Philosophical Journal, 1838. 



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