CAUSES OF QUAKES

Sun (Auckland), Volume III, Issue 921, 14 March 1930, Page 11

CAUSES OF QUAKES

EARTH MOVEMENTS EXPLAINED MANY MODERN THEORIES As a result of the recent earthquake iin the Murchison district of the South Island, an area of about 120 square miles was tilted up from one end to an elevation of about 15 feet above th*' normal, the general effect presenting a waving upheaval that staggered the This was stated by Mr. Preston Chambers during an address on "Earth Movements” which he delivered to the astronomical section of the Auckland Institute and Museum last evening Several sections of the address wer illustrated by lantern slides, some of which recorded the lecturer’s observations after the Murchison earthquake. Two fundamental principles had been advanced to explain earth movements. said the lecturer. They wer. isostasv and the radio-activity of the rocks. Isostasv was the idea of a warping lithosphere or outer crust of the earth adjusting itself to a contracting central mass, the warping creating weaknesses in the earth’s crust, which was believed to be the cause of earthquakes. The world gets out of equilibrium at times and was restored by drastic movements caused by radio-activity. Radio-activity created heat which be came so great that it melted the substratum on which continents rested, liquified the basalt and flowed out until it formed an equilibrium. This movement was supposed to occur at intervals of from 30.000.000 to 50,000,000 years and geological discoveries indicated five or six of these periods. CAME FROM WEST Referring to the Murchison ’quake, the speaker said that in the Marui . anil Matakitaki Valleys the greatest action occurred. The Matakitaki Valley ran approximately north and south and the wave came from the west. At the scene of the slip the houses were at a considerable distance from the hills that gave and the most surprising thing was the distance to which the mountain-side was hurlc*d. It was thrown with tremendous force. The wave appeared to have travelled at the rate of about eight miles a minute. The lecturer also touched upon volcanism as another cause of earth movements, and also erosion by water, which he illustrated by reference to the Grand Canyon. Also, movements were artificially produced by mining opera - lions.

He concluded by saying that the major portion of the whole question seemed to be beyond our present coni - prehension. Everything seemed lo point to a warping lithosphere adjust - ing itself to a contracting core < r kernel, the warping producing fra< - tures along which liquid matter movfd at periods according to its stress, ultimately settling to rest in equilibrium