The Wonder Book of Volcanoes and Earthquakes

by Edwin J. Houston

It is the opinion of Le Conte that if the records of all the earthquakes of 3,456 years had been thus made there would have been found during the entire time of Mallet's researches to have occurred no less than 200,000, while during the last four years of Mallet's records, the number would have probably reached two earthquakes per week.

Since Mallet's time, Prof. Alexis Perry published (1876) a much larger list of earthquakes. Perry finds that from 1843 to 1872 there have been 17,249 earthquakes, or 575 every year. Perry's list, however, is incomplete, since it fails to record earthquakes that occurred in mid-ocean, and in the unexplored and uncivilized parts of the world. So it seems likely that earthquakes are so common that our earth, at some part or other of its surface, is continually shaking or quaking.

Earthquakes are such tremendous phenomena that they were necessarily observed by the ancients. We find more or less complete accounts of them in various writings. Lucretius (Titus Carus Lucretius, a great Roman poet) speaks as follows, in his De Rerum Natura (On the Nature of Things). We use Munro's translation here:

"Now mark and learn what the law of earthquakes is. And first of all take for granted that the earth below us as well as above is filled in all parts with windy caverns, and bears within its bosom many lakes and many chasms, cliffs and craggy rocks; and you must suppose that many rivers hidden beneath the crust of the earth roll on with violent waves and submerged stones; for the very nature of the case requires it to be throughout like to itself. With such things then attached and placed below, the earth quakes above from the shock of great falling masses, when underneath, time has undermined vast caverns. Whole mountains, indeed, fall in, and in an instant from the mighty shock tremblings spread themselves far and wide from that centre. And with good cause, since buildings beside a road tremble throughout, when shaken by a wagon of not such very great weight; and they rock no less, where any sharp pebble on the road jolts up the iron tires of the wheels on both sides. Sometimes, too, when an enormous mass of soil through age rolls down from the land into great and extensive pools of water, the earth rocks and sways with the undulation of the water just as a vessel at times cannot rest, until the liquid within has ceased to sway about in unsteady undulations....

"The same great quaking likewise arises from this cause, when on a sudden the wind and some enormous force of air gathering either from without or within the earth have flung themselves into the hollow of the earth and there chafe at first with much uproar among the great caverns and are carried on with a whirling motion, and when their force, afterwards stirred and lashed into fury, bursts abroad and at the same moment cleaves the deep earth and opens up a great yawning chasm. This fell out in Syrian Sidon and took place at Ægium in the Peloponnese, two towns which an outbreak of wind of this sort and the ensuing earthquake threw down. And many walled places besides fell down by great commotions on land and many towns sank down engulfed in the sea together with their burghers. And if they do not break out, still the impetuous fury of the air and the fierce violence of the wind spread over the numerous passages of the earth like a shivering-fit and thereby cause a trembling."

Of course, no one at the present time believes this ridiculous explanation as to the cause of earthquakes.

Aristotle, a Greek philosopher, speaks thus concerning earthquakes. We quote the translation employed by Mallet:

"Three theories on the subject have been handed down to us by three different persons; namely, Anaxagoras of Klazomene, before him Anaximenes the Milesian, and later than these Democritus of Abdera.

"Anaxagoras says that the ether of nature rises upward, but that when it falls into hollow places in the lower parts of the earth it moves it (the earth); because the parts above are cemented or closed up by rain, all parts being by nature equally spongy or full of cavities, both those which are above (where we live) and those which are below. Of this opinion it may perhaps be unnecessary to say anything, as being foolish, for it is absurd to suppose that things would thus exist above and beneath, and that the parts of bodies which have weight would not on every side be borne to the earth, and those which are light, and fiery, rise; especially since we see the surface of the earth to be convex and spherical, the horizon constantly changing as we change our place, at least as far as we know. And it is also foolish to assert on the one hand that it remains in the air on account of its great size, and on the other to say that it is shaken, when struck from beneath upwards. And besides these objections, it is to be remarked that he has not treated of the attendant circumstances of earthquakes, for neither every time nor place is subject to these convulsions.