EARTHQUAKE WAVES.

West Coast Times, Issue 910, 22 August 1868, Page 4

EARTHQUAKE WAVES.

The following communication from Dr. Haas 1 , to the Editor of the " Lyttelton Times" will be read with interest :— I need scarcely apologise for offering you a few observations on the remarkable disturbance in the sea level as experienced to-day in Lyttelton harbor, -and in other localities on the coast of New Zealand, because in doing so, I hope to throw some light upon the causes by which this curious phenomenon has been brought about. I wish also to dispel some errors concerning it which are, as it seems, current among many of my fellow-citizens. In the first instance, it is not as your contemporary the "Star" of this evening states, "A Great Tidal- wave," but without doubt an earthquake wave in the sea, such as is commonly observed in- the adjacent seas, wherever any earthquake of consequence takes place, and followed in many instances by a volcanic eruption in or near the focus of the former. Although the shock transmitted through the earth's crust, travels much faster thau the sea wave takes to reach the same distance, the latter is of such a velocity that it travels at the rate of several miles in a minute, consequently, if the disturbance tinder review were the result of the volcanic phenomena observed a few months ago in the Sandwich Islands, as suggested in the same paper, it would have reached us the very same day. In confirmation of this assertion, I may be allowed to add a few facts which will show you that only a short time is needed for the transmission of such waves over great distances. During the great earthquake of Lisbon on the Ist of Nov., 1755, the shocks travelling through the earth, arrived in Madeira from the focus near Lisbon in twenty-five minutes (535 nautical miles), whilst the sea wave took two houri and five minutes more before it reached the same locality. In several islands in the West Indies, where the tide has only a rise of two feet to three feet, the sea rose suddenly more than twenty feet the same day. The earthquake at Valdivia, in Chili, on the 7th November, 1837, which was remarkable for its violence as well as for its great extent, caused violent agitations in the sea at Gambier's Islands, Tahiti, the Navigators and Vayao Islands, which consisted of repeated rising and falling of the surface of the sea. At the Vavao Islands these movements occurred on the Bth November, and continued every ten minutes for thirty-six hours. At the island of Opolu, one of the Navigators Islands, continuous earthquakes were felt on the 7th and Bth November after which oscillations of the sea took place. At Awrhu, one of the Sandwich Islands, the fluctuations of the sea occurred on the 7th November, and lasted during the whole night and till noon of the following day. At Hawaii also the water % fell nine feet in a very short time, and then rose suddenly twenty feet above high water mark. At the great earthquake which destroyed a Russian frigate in the harbor oi Simoda, Japan, on the 23rd December, 1854, this harbor was emptied and filled several times bj advancing and receding waves. In San Francisco, 4800 English miles from the scene of the earthquake, the colossal wave arrived 12 hours 16 minutes after it had left the harbor of Simoda, so that it must have moved at the rate of 6§ English miles in a minute over the ocean. The first wave caused a rise in the surface of the sea at San Francisco, which lasted half an hour. It was followed by seven smaller wares with intervals of an hour between. In San Diego the same phenomenon was observed, only the waves there came in later, and raised the surface of the water less. I may here add that no earthquake was felt at San Francisco, and thus the great disturbance of the ocean near that town would hare remained unexplained had the focus of the earthquake been in the high seas below the level of the Pacific ocean, < or on an island on the shores of a continent inhabited by savages only. It is consequently possible that we never may become acquainted with the primary cause of the phenomenon observed today ; at the same time we do as yet possess few reliable data for deduction or generalisation, but I have no doubt that as soon as all the material is collected we may be able to advance some steps towards the elucidation of this remarkable occurrence. But I may already state that all the news which reached us from the various ports of both islands, lead us to the conclusion that the focus of this disturbance lies in an easterly direction. From the telegrams already received, it is evident that the phenomena observed in the various parts, of the East Coast happened not only at different hour's, but also in a greater or lesser degree of magnitude. This difference may be easily accounted for by the direction of the earthquake wave, the configuration of the coast, the form of the coast, the form of the harbors and bays, the greater or lesser shallowness of the shores, and the depth of the sea a little distance off. _ General observations have already sufficiently shown, hi many parts of the world, that earthquake waves in the sea reach the coast with much less violence when the shores are steep and deep water is close by ; whilst at the head of long shallow bays their effect is very gradual and destructive. I have also heard that several persons experienced a slight shock of an earthquake this morning, between three and four o'clock ; one single perpendicular shock, apparently travelling from S.W. to N.E., accompanied by a slight subterranean rumbling sound ; and I only regret that no siesmometer has been placed anywhere in town to obtain conclusive confirmation of such an occurrence and of its direction. A Dutchman, with a bad wife, told his master that "she vos tronk all to tay Saturday night, and all to-night Sunday morning, and I vos so vild that I kick ter stairs rigkt down her." "I say, Jones, how is it that your wife dresses so magnificently, and you always appear almost out at the elbows ?" " You see, Thompson, my wife always dresses according to the 'Gazette of Fashion," and I dress according to my ledger." Pat's idea of sympathy was a good one. He had long been trying to give Bridget a parting kiss. Finally, as a last resort, he turned away, saying — Good-bye, Biddy ! Sure and ye haven't any sympathy for me at all at all?— " Sympathy, is it? And what d'ye mane by that, Patrick ?" — " Come here Biddy, and I'll be after tolling ye ! When I love ye so, that I'd like to bite a piece right out of your swate cheek, and ye fale, as if ye'd like to have me do so — that's sympathy, be jabers !" " Ah Patrick, you know my weakness ! Take a piece ; but be sure and lave it, so' that ye can take it again when ye come !" " ■•••.--