The Manawatu Herald. Thursday, March 4, 1909. THE CAUSE OF EARTHQUAKES.

Manawatu Herald, Volume XXXI, Issue 452, 4 March 1909, Page 2

The Manawatu Herald. Thursday, March 4,1909. THE CAUSE OF EARTHQUAKES.

Professor Mii.ne, E.R.S., who has charge o! the seismographs at Shide, in the Isle of Wight, gives this description of the cause of the earthquakes in Sicily and Italy. Writing to the London Daily Mail, he .says:—“l have personal knowledge of the district in which the great earthquake has occurred, hut were I to revisit it I should wonder whether my former visit had been a reality or merely a dream! What do these great convulsions mean ? What is their cause, and what are their effects from an historical point, of view ? We look to Italy as a teacher of the past; but, from the point of view of the earth’s history, Italy is one of the youngest of European countries, or, to be a little more definite, let me say that about the time when the materials were being deposited which formed the noble downs of Southern England, Italy was represented by a string of islands. . Since that time the subterranean ridge, the outcrop of which the islands represented, has been growing upward until the string of islands was joined to form the peninsula of Italy. This upward growth has not yet ceased ; the progress is still going on, and the face of the world in this part of Europe may be likened to that of an old man. As we grow older, muscular and adipose tissue gradually disappear, and the skin is left 100 large to cover the original surface ; therefore, it wrinkles. I'he action in Italy is still in progress. We have, for example, the olt-quoted

case of the Temple of Jupiter Serapis, early in ISOO, which was sinking at the rate of about an inch every four years. Since the Roman period, when the temple was built, the ground has sunk more than 20ft below the level of the ocean. A similar activity prevails along the coast of Italy, and we have many other illustrations of earth movement. But as the crust of our world is being in places crumbled upward, it is natural to suppose that corresponding depressions must be formed. The action is that of a concertina. When it is being closed, a ridge goes up and a parallel depression goes down. All this means that strain is beingproduced, and when limits are reached fractures take place, followed by sudden dislocations. These dislocations may be many miles in length. The main dislocatiou in the San Francisco earthquake seems to have had a length exceeding 400 miles. Along such a line huge masses of material fall downwards with a series of intermittent jolts. From what I can see by my seismograms at Shide. there were at least 15 of these in connection with the earthqake in Italy. The blows which those represented evidently reached the homogenous material which constitutes the interior of the world, and which, on account of its rigidity, announced the Italian disaster to every spot on earth provided with suitable instruments for recording it,”