DEFINITION OF EARTHQUAKE

Nelson Evening Mail, Volume LXIV, 15 January 1931, Page 3

DEFINITION OF EARTHQUAKE

VIEWS OF DR, P. MARSHALL

NO CONNECTION WITH VOLCANIC ACTIVITY (By Telcgraph-ASpecial to “Thp Mail") CHRISTCHURCH, This Hay. Vibration started from the fracture of a rock resulting from strain due to the expansion and contraction of the earth, was the definition of an earthquake given by Dr. P. Marshall, of Otago University, to the Teachers’ Summer School last night. He explained that when people felt seasick when an earthquake came it was not seasickness at all, but merely fright, because the earth which was usually regarded as solid moved up and down. The movement with earthquakes was never greater than about three inches. The vibrations were merely waves which emanated from the centre of the disturbance. Earthquakes which caused the whole earth to quiver occurred every fortnight, he explained, but these were not felt, only near the centre of origin. They were, however, recorded on seismographs. Probably the worst earthquake which New Zealand had experienced within the memory of man was the one at Murchison. Tremors were still shaking Tabaka, where the people were much alarmed, and wanted an investigation. It was not at all likely that a definite pronouncement could be made. Such shudderings usually took place as the earth settled into equilibrium when it was relaxing after the strain.

Earthquakes, he continued, seldom had any connection with volcanic activity. There was no relation between the two.