WHEN THE EARTH QUAKES

Manawatu Times, Volume XLIX, Issue 2307, 27 November 1925, Page 8

WHEN THE EARTH QUAKES

PROTECTING BUILDINGS FROM DANGER. “It Is a remarkable thing that a scientist, closed up in his observatory, can make our cities and towns safer for every one of us, and the speaker to-day, by showing how our buildings can suffer from earthquakes, has also shown us that the scientist and chemist are in close touch with everyday affairs of life,” said the Mayor, (Mr. F. J. Nathan) at yesterday’s meeting of the Palmerston North Rotary Club, in moving a vote of thanks to the speaker for the day. Tho latter was Dr. C. E o . Adams, of Wellington, Government astronomer and seismologist, a Martin Kellogg scholar, which entitles him to :wo years at Mount Wilson observatory, the greatest in the world. His subject was earthquakes. In his opening remarks he said that it might not strike his hearers that they lived in a state of constant oscllla* tion. After an earthquake had passed, we considered that the world had become still again, but this was not so to any degree of accuracy. There were in New Zealand records of earthquakes from the times of the earliest settlers, and careful notes had been kept in Wellington from the year 1848. Always were such ’quakes a test on the honesty and accuracy of men who erected buildings, for destruction or disruption occurred sometimes when a building was at fault. It was possible, and had been proved, that buildings could be erected that would withstand the effect of ’quakes which would otherwise have a very detrimental effeffet. For this, the principle on which one worked must be that earthquakes could not be avoided, but that by erecting buildings in the right way, some of the danger could bo minimised.

People were not always aware of the constant oscillation of this world, said the speaker, a 3 they paid attention only to the big shocks. But for every earthquake shock, large or small, there was a record kept in Wellington, and as a result it had been possible to make certain information available. Dr. Adams here produced charts from the earthquake recording machine, and showed how these made it clear that there was not one second of time in 24 hours when the earth uas not oscillating to some degree. Ho went on to explain now, by co-operation with Samoa, Sydney and Melbourne, the locality, intensity and range of earthquakes were established, not only in New Zealand, but throughout the Pacific. ~ By means of a machine, continued Dr. Adams, it was possible figuratively to see the centre of the earth, and to probe the forty-mile-deep surface layer of the earth to seek the origin of ’quakes, which generally started at from 25 to 30 miles down. It was even known at what speed earthquakes travelled through this layer, but the next earth strata was not so well known owing to different physical properties. In applying his subject practically, the speaker said that all buildings should be monolithic —not of mixed construction ,such as ,for instance, a brick front and a wooden back. A building had a certain amount of inertia .and different waves in an earthquake wanted to oscillate it so that if a building was of mixed construction, different, portions oscillated at different times to different waves. If a building oscillated quicker than a wave, then a break at the foundations followed. Thus if a building was composed of only one material, it would oscillate at the one time and be removed from the danger zone. A wise man who found his building; in danger would stiffen the structure. At the conclusion o£ his address, the speaker was accorded a hearty vote of thanks*