THE NOISE OF EARTHQUAKES.

Southland Times, Issue 990, 22 July 1868, Page 2

THE NOISE OF EARTHQUAKES.

, (Prom " Maitland Mercury.") The very noisy sound produced by the earthquake on the night of the 18th June have caused a good deal of wondering speculation as to the cause of the noise. The previous impression of most persons was, from reading, that a rumbling sound, more or less loud, was the noise invariably attending earthquakes. And that was the kind of noise actually heard by a good many persons in the houses less seriously affected. They thought of rolling thunder, or of laden coaches passing the house, or of some heavy substances quickly dragged along a gravel road &c. — all modifications of the rumbling sound. But in many houses where the shock (or shocks) was felt more severly, the impression produced was quite different* People, suddenly awakened, thought the house was tumbling down about them ; or that a part of their house was then actually falling down ; or they lay in momentary expectation that the sound of heavy "articles tumbling about in the attic or in the roof itself overhead would be immediately followed by the fall of the upper part of the house upon them. Our Raymond Terrace correspondent, it will have been noticed, heard still the same unaccountable noises overheard when he had hastily run out of doors, while in the house he thought the roof was crushing down on him; but the moment he was out of the house he thought of some enormous meteoric crushing going on in the air above him. An open-air observer in Maitland heard, as he thought for the moment, a mighty wind roaring through a forest, rapidly approaching him, and then the sound striking him with a rush and a kind of electric shock, but no wind accompanying it. We may imagine that these various reports as to the kind of sound heard indoors are partly due to the fact of people being suddenly awakened, and being con r fused ; and partly to the ever-varying acoustic properties of different houses and different rooms in a house. But a thoughtful observer, who was a certain at the first moment his house was tumbling about him, suggests as the cause of these extraordinary sounds, that — the crust of the earth being supposed to-be some three iniJes, or say 16,000 feet in thickness — the earthquake was splitting up and disturbing the relative position of the rocky layers, perhaps thousands of feet below the surface of the earth ; and that the tremenduous rolling, grinding, falling sounds may have been thus generated so far below us, and their faint echoes have been heard by us as pervading all the air around us. Certainly it is wonderful that so very few houses have had more than the piaster slightly broken when such awful Bounds of crushing power were heard in the houses. It may be of interest to learn whether any difference is observable in deep wells, or in mines, since the earthquake. The water in a well in Olive-street, "West Maitland, is stated to have fallen four feet lower since, but whether the bottom of the well itself has also lowered we have not heard. . Bnt it is hardly to be expected that in West Maitland, situate

on alluvial soil of unkaown depth — norock has ever yet been reached in wellsinking in it, "we believe— such changes would show so strikingly as they would in other places.