WESTPORT 'QUAKES

Wanganui Chronicle, Volume 74, Issue 109, 11 May 1931, Page 8

WESTPORT 'QUAKES

“NOT EXTRAORDINARY" REASSURING STATEMENT According to Mr F. Baird, of the Christchurch Magnetic Observatory, th< detonations heard at Westport need cause the people no alarm. In many parts of the world underground explosions of this sort have gone on for hundreds of years. Mr Baird explained that the. noises were caused by movement of the ( earth’s outer crust in relation to the t semi-plastic material that is reached if a deep enough tunnel is dug through the solid outer crust. The movement, he said, was like the movement of the water in a lock on a canal. The plastic | material rose and fell in a similar man nor. If the lock were to be covered with ice, the analogy would be closer In the event of the water level in an ice-covered lock being lowered, a great strain would bo put upon the. ice. Il would crack, ami detonations would occur. This form of noise was quite distinct from the explosive noises caused by volcanic action. Potent Causes As a further analogy, Mr Baird said that the earth could be likened to a tennis ball filled with water. If this ball had a small crack or hole in it, the water would squirt out if the ball were squeezed. If the ball had no crack, and enough pressure were applied, it would bulge out of shape in certain places. The cracked ball was analogous to a volcano, and the other action of an earthquake. “I very much doubt if tho full moon has a great deal to do with causing the noises,” said Mr Baird. “It is quite probable that tidal action has something to do with the noises, but it would be by no means the only cause. There are other very potent which have been neglected. Mr Baird has recently returned from un inspection of the district affected by the Murchison earthquake, and says that rumblings are still going on in the Murchison and Golden Bay districts. On the eastern coast of the United States the Indians had noticed rumblings in certain places for hundreds of years, and in other parts of the world the same phenomenon had been noted over long periods. “This doesn’t mean anything extraordinary,” said Mr Baird. “It certainly doesn’t mean that there is a big shake coming, or that there is volcanic activity. There is no evidence that rumblings mean that an earthquake is coming.” A Vast Subject The whole subject of earthquakes was so vast that relatively very little was known about them, Mr Baird continued. Scientists all over the world were at work on earthquakes, but the subject was so big that it had not been gone into fully yet. It was known, however, that earthquakes were caused by the rising or falling of the semiplastic layer which extended right round the earth at a depth of 40 kilometres. This movement imposed strains on the solid crust of the earth, and fractures or bulges resulted, sometimes causing earthquakes. “Volcanic action is purely local, bur earthquake activity extends over a wide area,” said Mr Baird. “The origin of the Buller earthquake, for instance, extended over a very much larger area than people imagine. The West Coast people need not bo alarmed. 'Pho noises there do not mean that anything serious is coming.”