SEAQUAKES

Marlborough Express, Volume LX, Issue 230, 29 September 1926, Page 7

SEAQUAKES

SUBMARINE ER U PTIONS . ALAR.JVF ON SHIPBOARD. STRANGE EXPERIENCES WHEN TRAVELLING. We speak of earthquarkes, bui are more quakes on sea than on land. Human experi©nc© has mad© terra fivma an illusion. The man who has experienecd a genuine earthquake lvill no longer bolievo that he has solid ground be»eath his feet. When he has left ■I no earfch trembie and swell into Waves and ridges nioving along like water, when lio has become conscious If TTea ^e seasickness and lioars Taternl, mysterious rumblings as if the globe wero in pain, he becomes aware of his insignificanc© and helpiessuess and the instability oi even the eternal rocks. lf an earthquake is ac-oompanied b.y such nnpleasanfc results, what niust be tho effect of a seaquake? h irst comos a deep rnmbling sound, thcn a series of shocks, nnder which the ship trembles or seenis suddenly to stop as if it had mu agronnd, says ihe Melbourne Age. Perhaps after a number of shocks tho ship- appears to slido over a shoal and resiime her wurse. On the morning of ihe San trancisco earthquake a ship soine way off experienoed heavy shocks as ti she had struck bottom threo times and then slipped over 11 shoal. The weather was quite cairn and the sea Iperfectly smooth. Tn the same legion and ahout the same timo another steamer "seemed to jump clear out of the water, the engines raced fearfully, as though the shaft or wheel had gone, and then a violent trembling fore and aft and sideways, reminding me of running full speed against a, wall of ice." That is how a chief engineer described his experi©ncc. The niisory and alarm of t-his kind of thing is that it is in such shriekmg contradiction with -ippearanoes. Tho sea may be without a ripple and tho surface smooth as glass when eomes a shoek severo enougli to rouse the crcw from sleep and send them rushing to the declc. I11 1878 a Britnsh llcet was stationed in tho BosJphorus, when an earthquarke was felt on both the European and the Asiatic shores. A strange sound was heard and the ship began to trembie as though she wero running on a Bandbank. Persons ooming up the companion way wero thrown over. Tho vibration contiriued for somo seconds, and water bubbled up from beneath the ship, but the upper surface remained quite cairn. Other rejports described tho water as rising up in a s'olid mass and fprming a. fiat dome without ruffling its surface. One explanation is tlio familiar one , of submarino volcanoes. DATA ANALYSED. Professor Rudolf, of Strasburg, hrought together and analysed a mass of data relating to submarine earthquakes and eruptions, and his oonclusions are briefly put thus: — (1) Submarine earthquarkes and | eruptions occur in all depths of the 1 sea, upon the submarino ridges, as

well as in the regions of depression. (2) The frequency and intensity of manifestation of the seismic and eruptive forces is not dependent upon tho distance from activo or extinct volcanoes. (3) Thero are habitual regions of sliock, and portions of tho ocean that are quite free from earthquakes; with the exception of the latter, seaquakes occur, also isolated and scattored over tho ocean. Tho areas within which seaquakes occur are those with sharp clianges in steepness of the ocean floor. The movements are investigated through what happens to deep-sea cables, which lie stretched on the bottom of the ocean. On level plains the cables may lasb for twenty years or more, but when there are steep walls on the margins of tho deep the cables have a hard time, and are often fractured. Tliey may be crushed or separated by nbraison, or geb strained jyid frayed out afc the end, or their suspension in the water is shown by a coating of shells of coral. There has been a sudden displacement of their bed, or they have been buried in material owing to some landslip from a neighboring slope. One cahle was interrupfced five times near the same point where it erossed a line marked at int rvals by isubmerged volcani'c peaks. At a place where at intervals of te:i miles three trans-Atlantic cables run parallel all tliree were simultaneously fractured at ix>ints lying i 11 a straight line. At Zante. in Greece, there is a district famous for its great seismic activity and the irregularities of the sea bottom. Some of the submerged precipices are from 3000 to 5000 feet high. Tb is not far from tho bow to tho stern of a repa-ir ship. but even in that short distance a difference of 2000 feet has been reeorded. In 1885 the cablc between Zante and Creto was injured by tho floor dropping suddenly from 700 to 10,000 feet. The cablc was jammed under a mass of material. CHANGES IN THE SEA BOTTOM. The inference to be drawn fiom these data is that the changes' in configuration of tho sea bottom take place by leaps and bounds, and nro greater than any observed on tho land. Last year the German research ship Meteor discovered tliree nevv ranges of mountains under the ivaters of Ihe Atlantiq, between Buenos Aires and Capetown. One of ihe peaks rises !o abpub the heighb of M011 b Blanc, but beforc it could show itself above the surface of the water a Ben Nevis ivould need to be set on top of it. Surely a, new vcrsion of Peliou upon Os.?a! On ihe other 1 1 and , w© 1 1-ki rown sub m ari n e . mo untains keep disappearing, and islands are occaisionally bcing tlirown up. One island heaved up over 160 years ago slipped down out of sight in 1888. One allcd Old Bogdslov rose in 1883. I'hen in 1906 surveyors announced that the two Bogoslovs had a baby, a little island somo 56 feet high. They called the liewcomer Perry Peak, but as there were 110 infant welfare eentres oonvenient poor little Perry Peak suddenly died, and was buried in his native element. It has been notcd that earthquakes are frequently followed by destructive water waves rushing in from the sea and causing great dcstruction of life and property. Such a wave corning suddenly after a strong ebb Lido desti-oyed thousands of Persian

soldiers at Potidaea, and it may be that a similar wavo, following upon a seaquake, destroyod Pharaoh's army in ihe Rod Sea. Professor Rudolf believed that such. occurrences wero due to an outbreak of some submarine volcano. It is singular tbat the earliest instrument for determining the shock direction of an earthquake was made in China in tho year 136 F».C. It was a hollow brass rod with a pendulum free to mov'c in all directions. M any devices lia.ve been invented sinco thcn, but tbe order of tlie day is tlie self-registering instrunient. In olden times Poseidon, or Neptune was worshipped as the earthquake gotl. His abode ivas Peloponnesus, and a chain of sanctuaries was erected in his honor. Other nations ascribed earthquakes to the movements of a great spider. a hog, a. mole, or a tortoiso, but it is significant that the Greeks made the sea gol the author even of earthquakes. A1.1 American earthquake prophet savs the world is yet to witness a cataelysm comparable only to Noah's flood that one-third of the surface of the earth will crumble under the sea., and a, new continent rise in tlie South Scas, that Japan, China, the mest of the countries of Europe and Nortliern Africa will be swallowed up. Well. tbis stupendous catastrophe would end manv things and begin a new cycle of old problems. But the phenomena of seaquakes leave an uncanny t'eeling. Against these things tho genius of man is helpless. This old globe of ours has not yet reached its final form. It groaneth and travelleth 111 pain until now.