EARTH TREMORS

Hokitika Guardian, 2 November 1929, Page 6

EARTH TREMORS

CHARACTERISTICS AND CAUSES. amd. their peculiarities were discussed by Dr. C. E. Adams (Government Astronomer) in an address .to the Wadestown and Highland Park Men’s Society last week. The biggest shake experienced in recent times, said Dr Adams, had been the last one. On this occasion ■the uplift had been almost vertical, in contrast to the San Francisco disaster, when, the motion had been rather horizontal. Dr Adams said he wished to make “a plea for the earthquake.” Except for disturbances of this type there would be no mountains, as these would gradually be worn down by erosion. It was difficult to sav just what an earthquake was. Those of volcanic origin were only severe in the immediate locality, the amount of material shifted being usually small.! No' (explosion was (capable of shaking the world as an earthquake does. It was more probable that the latter was caused by land masses giving way under an ever-increasing strain.

These concentric spheres possessed different characteristics, varying in elasticity and' density: The external crust was apparently about 38 miles in thickness. Beneath lay a more solid layer extending for over 700 miles, and third layer extending from 750 to 1000 miles. There was a remarkable instance of the recording of our own Murchison earthquake in iSjpain. It was significant that the seismological authorities there had sent out their vertical (as opposed to horizontal) record of, the shake. The time taken to reach Spain had been 28 minutes. i Earthquakes, concluded Dr Adams, were really the “growing pains of the earth,” and it would be foolish, even were it possible, to try and stop them. In reply to a question as to whether ’quakes could be predicted, Dr Adams said that he did not know whether such information should be released or not, even if it Mere ascertainable. Certain precautions in architectural design could be taken against moderate earthquakes, continued the speaker. In his opinion there was not enough standing-room in the streets of Wellington in the event of a big earthquake; subsidiary reservoirs were required in case the mains burst; more adequate exits from theatres, etc., and a thousand and one points far more important than tho prediction of an earthquake on a certain day.