TREMBLING EARTH.

Taranaki Daily News, 2 August 1930, Page 1 (Supplement)

TREMBLING EARTH.

MORE GOOD THAN HARM.

(Rev.

B. Dudley,

F.R.A.S.)

Probably, wore we living within the region of the disasters caused by the earthquake in Italy, and personally affected directly or indirectly by the havoc it has made, we should feel that any reference to earthquakes as being in any sense advantageous was most inappropriate and untimely. Even among ourselves, at this distance, there may exist the like sentiment. . Second thoughts, however, suggest that the present is exactly the moment for being reminded to what extent seismic disturbances such as the one that has resulted so unfortunately for thousands of pur fellow human beings are in the long run favourable rather than adverse to mankind.

A New Zealand pastor is reported- to have startled his congregation by in- | eluding in one of his public prayers the ! petition that Providence would “con- ; tinue the benign ministry of' the i earthquake.” Perhaps the plea was meant to be. taken according to -its moral as well as its physical interpretation. He was, however, widely read' in science, and not unacquainted with the value -of earthquakes • as : «, means of preserving the balance of .forces in nature. More often, doubtless, the- prayers of worshipping congregations have been guided in a totally different direction, the phenomenon being thought of rather as an enemy to be dreaded. There has not always been the recognition that these upheavals are really friends in disguise. It is no easy matter to determine the causes to which the various kinds of earth tremors are due. Several tentative explanations have been given. According to one of these they are tne result oF the cooling of our planet, which, if theory is correct, was once ait incandescent mass. Heat was lost by radiation, the zone beneath the part which had already become solid meanwhile contracting, thus causing that solid part to wrinkle, like the skin ot an apple when it is drying. At times a gap would occur between the more plastic zone and the upper (already cold) layer. Under the stress of gravitation, collapse and fracture would take place. Another explanation is that the strain produced is due to the rotation of the earth acting upon a crust unequal in strength. A more likely guess is that which assigns the cause to attempts to assume a form of perfect equilibrium. Quite clearly earthquakes do relieve the situation for the living population of the world. As has been said, “had no earthquakes taken place in olden times man would not now be alive on tire'face, of the earth; if no earthquakes were- to take place in future, the'term of man’s existence would be limited within a range of time far less than that to which it seems likely, in all probability, to be extended.” It is certain that when once continents and-lands had been formed there began a struggle between the destructive and restorative (or preservative) forces. Water and land ate- sworn enemies. In the- first place,-the-sea has ever tended to destroy land by continually washing its snores —a slow process, but very real and ’ powerful. As the land y V as slowly eateh away, the longer the process continued, the higher the would rise and the greater power it would possess to bring about the dissolution of the remaining land, the effect being, of course, cumulative. Islands formed of such ipparently irresistible substances as granite, gniss, and other hard, rocks, have yielded in an appreciable degree to the violence of the Atlantic, so that during historic times the changes brought about have been distinctly noticeable. One authority, picturing the effects in the Shetlands of such operations, says: “The most sublime scene is where a. mural pile of porphyry, escaping the process of disintegration that is devastating the coast, appears to have been left as a sort of rampart against the inroads of the ocean. The Atlantic, when provoked by -wintry gales, batters against it with alt the force of real artillery; and the waves, in their repeated assaults, have at length forced for themselves an entrance. This breach, named the Grind-of the Navir, is widened every winter by the overwhelming surge that, finding a passage through it, separates large stones from its aides, and forces them to a distance of no less than 180 feet.” A second destructive force is the raid-, fall. The fact that great deltas have been formed, and whole conthi mte grown up by the action of the rainfall, is sufficient evidence of the extent to which it tends to destroy and disintegrate the land. It was Sir John Herschel who once said that, “had the primeval world been constructed as it now exists, time enough has elapsed, and force enough directed to that end has been in activity, to have long ago destroyed every vestige of land.” These destructive forces give rise to a levelling action. Their influence, that is to say, is in. the direction of reducing the solid part of the earth to the figure of a perfect sphere, taking down all irregularities, and thus destroying the conditions that are required to preserve habitability. Earthquakes are, on the other hand, the means of producing irregularities, and so of rectifying the work of water in the form of rain «.nd the continual ravages which the sea commits upon tlie ■ laud. In other words, the earth’s subterranean forces make for the conditions which are required to counteract the continual disintegration of the shores and interior parts of continents. Necessarily, if the earth is upheaved in one place it muss be depressed in another, and thus the balance between uph&aval and depression is maintained. Thia view ot the case does not, however, alleviate the sinister result of the phenomenon—the destruction, often, on a large scale., of precious, human lives, to say nothing of the wreckage of property. Among the recorded earthquakes within the past 60 years have been very disastrous visitations in Peru, Equador, Aleppo, Krakatoa, Japan,' and Mont Pelee, involving the loss of 150,000 lives. Although it is not easy in the light of these figures to think how good comes out of ill, the fact remains that t-iiero is a preservative value in the earthquake.