EARTH MOVEMENTS

Hokitika Guardian, 4 August 1931, Page 5

EARTH MOVEMENTS

ANOTHER BIG SHAKE UNLIKELY.

DR. MARSHALL’S VIEWS

“As far as the teachings of the past can tell us, it is not likely that we will have another big earthquake in New Zealand, seeing, that we have uad two in recent times,” said Dr. P. Marshall, of the Department of Scientific and Industrial Research, when speaking on “Earthquakes and their Physical Effects,” to members of the New Zealand Institute of Architects on Thursday evening. j Dr. Marshall began his address by describing earthquake .waves and tliedr movements, and stressed the distinction between compression waves and trans-verse waves. The ..rumble and shiver that was felt just before a big quake, be said, was caused by the compression waves, and the shock itself by the trans-verse waves. If the centre of the quake was far away the shock would, not be felt till some appreciable time after the rumble had been heard, but if the centre was close, the two actions would come practicnlly simultaneously. Earthquakes were very ordinary phenomena, he said. Though in New Zealand a great number were felt, there were tremors in nearly every country in the world, and some countries that had had them with very great severity were now practically immune. The two greatest felt in Wellington were those of 1848 and 1855—the latter one had raised the ground five feet, a really gigantic force. There were very few places in the world that had lied two destructive earthquakes, however, and Wellington had. That, in his opinion, would have relieved the earth stress and it, seemed reasonable to think that there would not be any more.

Many people bad tbe habit of sayj ing, on hot, muggy days, “This is just j the weather for an 'earthquake,” he said, some went further and allied earthquakes to an eclipse of the sun jor the moon. Dr. Marshall assured | his audience that earthquakes were catalogued extremely carefully, . and from the data available it was apparent that there was no astronomical or meteorological relationship in earthquake frequency. As far as the Napier earthquake was concerned, Dr. Marshall said that he was convinced that a great deal of the blame that had been laid at the d.oors of faulty construction and faulty material in buildings was really attributable to the fact, that there was an astounding variation in earthquake inI tensity in very small distances. In the ! Napier cemetery, for instance, some of the headstones had been flung long diis.. tehees by the earthquake,..while others, almost adjoining, had barely shifted. The speaker showed a number of TanHern ' 'plio'ingi’a piles' 1 of file V of the earthquake at Napier an further along the roast Mm,