EARTHQUAKES 



iossal mountain, chain of Quito, Pasto, and Popayan no lees 

 than by numerous valleys and clefts, and they are 436 miles 

 apart. The sound was certainly not propagated through the 

 air, but through the earth, and at a great depth. During the 

 violent earthquake of New Granada, in February, 1835, sub- 

 terranean thunder was heard simultaneously at Popayan, Bo- 

 gota, Santa Marta, and Caraccas (where it continued ibr seven 

 hours without any movement of the ground), in Haiti, Jamai 

 oa, and on the Lake of Nicaragua. 



These phenomena of sound, when unattended by any per- 

 ceptible shocks, produce a peculiarly deep impression even on 

 persons who have lived in countries where the earth has been 

 frequently exposed to shocks. A striking and unparalleled in- 

 stance of uninterrupted subterranean noise, unaccompanied by 

 any trace of an earthquake, is the phenomenon known in the 

 Mexican elevated plateaux by the name of the "roaring and 

 the subterranean thunder" (bramidos y truenos sufiterraneos) 

 of Guanaxuato.* This celebrated and rich mountain city 

 lies far removed from any active volcano. The noise began 

 about midnight on the 9th of January, 1784, and continued 

 for a month. I have been enabled to give a circumstantial 



* Ou the bramidos of Guanaxualo, see ray Essai Polit. sur la Nouv. 

 Espagne, t. i., p. 303. The subterranean noise, unaccompanied with 

 any appreciable shock, in the deep mines and on the surface (the town 

 of Guanaxuato lies 6830 feet above the level of the sea), was not heard 

 in the neighboring elevated plains, but only in the mountainous parts 

 of the Sierra, from the Cuesta de los Aguilares, near Marfil, to the north 

 of Santa Rosa. There were individual parts of the Sierra 24-28 miles 

 northwest of Guanaxuato, to the other side of Chichimequillo. near the 

 boiling spring of San Jose de Comangillas, to which the waves of sound 

 did not extend. Extremely stringent measures were adopted by the 

 magistrates of the large mountain towns on the 14th of January, 1784, 

 when the terror produced by these subterranean thunders was at its 

 height. " The flight of a wealthy family shall be punished with a fine 

 of 1000 piasters, and that of a poor family with two months' imprison 

 meat. The militia shall bring back the fugitives." One of the most 

 remarkable points about the whole affair is the opinion which the mag- 

 istrates (el cabildo) cherished of their own superior knowledge. In 

 one of their proclamas, I find the expression, " The magistrates, in their 

 wisdom (en su sabiduria), will at once know when there is actual dan- 

 ger, and will give orders for flight; for the present, let processions be 

 instituted." The terror excited by the tremor gave rise to a famine, 

 since it prevented the importation of corn from the table-lands, where 

 it abounded. The ancients were also aware that noises sometimes ex- 

 isted without earthquakes. Aristot., Meteor., ii., p. 802 ; Plin., ii., 80. 

 Tho singular noise that was heard from March, 1822, to September, 

 1824, in the Dalmatian island Meleda (sixteen miles from Ragusa), and 

 on which Partsch has thrown much light, was occasionally accompanied 

 bv shocks. 



