Continents May Be Gradually Sliding

Sun (Auckland), Volume III, Issue 699, 26 June 1929, Page 11

Continents May Be Gradually Sliding

STARTLING THEORY ORIGIN OF EARTHQUAKES to THE SUN) CHRISTCHURCH, Today. Are the continents of the world gradually slipping from the Northern Hemisphere to the South, from the Atlantic Ocean to the Pacific?

Such a theory of earth-wide gravitation was explained to a "Sun’’ reporter by Professor R. Speight, Professor of Geology, at Canterbury College, during a talk on the possible connection of volcanoes ajid earthquakes. It had been advanced, said Professor Speight, that Asia was moving toward Australia, and North America to South America: such movements would explaid the prominent zones ot volcanoes and earthquakes in the East and West Indies.

There was a good deal of misconception, began Professor Speight, about the connection of quakes and volcanoes. Earthquakes were classified in two groups: volcanic, and tectonic, or structural. Volcanic 'quakes were immediately associated with volcanoes and occurred only close to vol canoes before or after eruptions, and were rarely severe. They were caused probably by strains set up in the mountain, through explosions, steam, or the advance of lava. Earthquakes near Tongariro, Ruapehu or Rotorua would be volcanic in origin. Only once had damage been caused: this at Ischia Island, where several thousand people were killed, although 22 miles away, at Naples, the shock was not felt.

Tectonic ’quakes had no connection with volcanic action, and affected a wide area of the earth. They frequently occurred in districts where there were no volcanic rocks, such as Murchison. . Even in districts where volcanoes occurred, they were practically independent There was. for instance, no obvious connection Between the volcanoes of the Andes and the earthquake regions thereabout. The four great earthquake regions were in the Himalayas, the Andes, and the East and West Indies.

“Is there anything to be said of the connection of earthquakes and volcanoes?” asked Professor Speight. “We don’t even know the ultimate cause of either action: both probably come from the very depths of the earth’s crust.”

Certain facts did suggest sympathy between the two actions. Earthquakes on one point of x-ibbey’s Circle, an imaginary line drawn round the world practically through the equatorial regions, were frequently accompanied by volcanic eruptions on another point of the line. It was notable, too, that the two parts of the earth most susceptible to quake action —the East and West Indies —were those where volcanic action also was at its maximum, ft was known that the earthquake centres were often parallel to the volcanic ranges, suggesting some common, ultimate cause of both actions. Chief of several interesting speculations connecting the two actions was the theory that the continents of the world, gradually sliding, -were producing disturbances in the regions in their paths. This theory would account for disturbances in the East Indies, where Asia was approaching Australia, and in the West Indies, where North America was moving toward South America. There was also a tendency for all continents to gravitate toward the Pacific as well as southward; the rotation of the earth was said to be the cause of such a movement. Finally, said Professor Speight, there was a belief that ’quakes were due to radio-activity. The scientific world knew the immediate causes of earthquakes; what it searched for now were the ultimate, deep-seated causes which produced dislocations in the earth’s crust.

NOT VOLCANIC PROFESSOR ON NELSON EARTHQUAKES STRESSES NOT BALANCED Press Association DUNEDIN, Today. Professor Park, of the Otago School of Mines, says that the Nelson earthquakes were not volcanic, but were due to earth movements which will continue until the internal and crustal stresses reach a state of equilibrium. There was no evidence of volcanicity in any part of the Nelson district for nearly two whole geological epochs, he said.