Submarine volcano

“ There are three active volcanoes in the New Hebrides group—those of Ambrym, Lopevi and Tanna. In 1897 a submarine volcano broke out near the north coast of Tonga. It had great force at first and for a time its eruptions were usually frequent. A submarine volcano also showed itself some twenty years ago near Erromanga. ”

“ The hypothesis which has been several times put forward, according to which the closed ring or annular form of the coral-reefs in Atolls or Lagoon Islands marks the configuration of a submarine volcano, the structure having been raised on the margin of the [77] crater, is opposed by their great dimensions, the diameters of many of them being 30, 40, and sometimes even 60 geographical miles. Our fire-emitting mountains have no such craters ”

“ Schematic representation of a typical submarine eruption in the open ocean.
The unlimited supply of water surrounding submarine volcanoes can cause them to behave differently from volcanoes on land. Violent, steam-blast eruptions take place when sea water pours into active shallow submarine vents. Lava, erupting onto a shallow sea floor or flowing into the sea from land, may cool so rapidly that it shatters into sand and rubble. The result is the production of huge amounts of fragmental volcanic debris. ”

“ We now possess the record of numerous islands lifted above the waters, and others sunk beneath the waves, accompanied by storms and earthquakes similar to those which marked the destruction of Atlantis.
In 1783 Iceland was visited by convulsions more tremendous than any recorded in the modern annals of that country. About a month previous to the eruption on the main-land a submarine volcano burst forth in the sea, at a distance of thirty miles from the shore. ”

“ Here nature is prodigal with her gifts to man, and the cocoa-palm, cinnamon and other trees flourish, and rice, cotton, the sugar cane and tobacco yield their increase under cultivation. But beneath these scenes of loveliness, there are terrific energies, for this region is a focus of intense volcanic action. In the Sunda strait, between Sumatra and Java, there lies a group of small volcanic islands, the largest of which is Krakatoa. It forms part of the “basal wreck” of a large submarine volcano, whose visible edges are also represented by Velaten and Lang islands. ”

“ In this pastoral territory, also, though they hardly affect the scenery, volcanic rocks come to the surface where the foldings of the earth's crust have brought up the oldest formations. Their appearance extends over so wide an area as to show that a large part of these uplands lies on a deeply-buried volcanic floor. A whole series of submarine volcanoes, extending over an area of many hundreds of square miles, and still in great part overlain with the accumulated sands and silts of the sea-bottom, now hardened into stone, underlies these quiet hills and lonely valleys. ”

“ MacCulloch, after examining with great attention these and the other igneous rocks of Scotland, observes, "that it is a mere dispute about terms, to refuse to the ancient eruptions of trap the name of submarine volcanos; for they are such in every essential point, although they no longer eject fire and smoke." ”

“ At fifty feet above the peak, in the midst of a rain of stones and scoriae, a large crater was vomiting forth torrents of lava which fell in a cascade of fire into the bosom of the liquid mass. Thus situated, this volcano lit the lower plain like an immense torch, even to the extreme limits of the horizon. I said that the submarine crater threw up lava, but no flames. Flames require the oxygen of the air to feed upon and cannot be developed under water ”

“ The secrets of the sea have been investigated so well that no destructive agent is likely to exist that is not known to science. Collision with a whale would not damage a liner, though it would be bad for the whale. The sea serpent may be dismissed without comment. The eruption of submarine volcanoes may be dangerous to small vessels, but the idea of harm from them can not be entertained in connection with the Atlantic service. ”

“ The subterranean fires, the source and cause of volcanic eruptions and earthquakes, act also on the beds which form the bottom of the sea. When the vents formed by volcanic action lie beneath the waters of the ocean, they are called "submarine volcanoes." The existence and action of submarine volcanoes, long suspected and conjectured, has since the beginning of this century been clearly proved, by the formation of new islands above the waters of the ocean.
The first well-ascertained instance of the elevation of a new island by a submarine eruption, occurred in 1811, near St. ”

“ The line of ancient subterranean fire which we trace on the Mediterranean coasts has had a strange attestation in Graham’s Island, which is also described as a volcano suddenly bursting forth in the mid sea between Sicily and Africa; burning for several weeks, and throwing up an isle, or crater-cone of scoriæ and ashes, which had scarcely been named before it was again lost by subsidence beneath the sea, leaving only a shoal-bank to attest this strange submarine breach in the earth’s crust, which thus mingled fire and water in one common action. ”

“ It seems impossible to refer the phenomenon now under consideration to any original uniformity in the configuration of submarine volcanoes, on the summits of which we may suppose the coral reefs to grow; for although it is very common for craters to be broken down on one side only, we cannot imagine any cause that should breach them all in the same direction. But the difficulty will, perhaps, be removed, if we call in another part of the volcanic agency—subsidence by earthquakes. ”

“ At five o’clock John Mangles could discern a light smoke rising from it.
“Is it a volcano?” he asked of Paganel, who was gazing at this new land through his telescope.
“I don’t know what to think,” replied the geographer; “Maria Theresa is a spot little known; nevertheless, it would not be surprising if its origin were due to some submarine upheaval, and consequently it may be volcanic.”
“But in that case,” said Glenarvan, “is there not reason to fear that if an eruption produced it, an eruption may carry it away?” ”

“ Was the Cretaceous Ocean shallow all round this continent, and did it suddenly subside to fill some tremendous chasm caused by a sudden submarine shrinkage of the earth’s crust, followed by the inland sea, which naturally rushed out into the vacancy?
“What seems the only real danger to Australia lies not in the eruptions of some suddenly created new volcano, or any ordinary earthquake, but in just such shrinkages in the sea bottom as occurred on the coast of Japan, off Fraser Island, and many other localities, including Lisbon and Port Royal. ”

“ Besides this submarine eruption, the volcano Skaptar-Jökull, on the mainland, on June 11th, 1783, threw out a torrent of lava, so immense as to surpass in magnitude the bulk of Mont Blanc, and ejected so vast an amount of fine dust, that the atmosphere over Iceland continued loaded with it for months afterwards. ”

“ The active rock was refractory basalt, semisolid, crusting and breaking into blocks as it rose from a submerged crater.
On September 1 after we left, the crater exploded, throwing sand and dust a distance of 100 miles to the east. The middle heap was engulfed, leaving only a lagoon; and the remaining peaks were shrouded in a heavy mantle of debris. Such a history of building and bursting and spreading out as a shoal has gone on for more than 111 years. Bogoslof is the peak of a submarine Pelée, several thousand feet above sea bottom. It is always active, the index volcano of the Aleutians. ”

“ It was right on the line of volcano spacing extending from White Island in the Bay of Plenty, to Ngauruhoe and Ruapehu Volcanoes, beyond Lake Taupo at the south. Here was a land of echelons of deep cracks, building up along scores of miles from submarine eruptions such as Falcon Island in the Tonga group. Farther south is the dangerous looking White Island close to the New Zealand shoreline, resembling Bogoslof, and so on to the lava volcanoes at the south. Big earthquakes have been characteristic, along with uplift, of both shorelines of Cook Strait. ”

“ In Europe, Vesuvius (p. 231) and Etna began their career as submarine volcanoes in connection with earth movements which finally lifted Pliocene deposits in Sicily to their present height,—four thousand feet above the sea. Volcanoes broke forth in central France and southern Germany, in Hungary and the Carpathians. Innumerable fissures opened in the crust from the north of Ireland and the western islands of Scotland to the Faroes, Iceland, and even to arctic Greenland; and here great plateaus were built of flows of basalt similar to that of the Columbia River. ”

“ Besides the rocks which carry this internal evidence of submarine deposition, are many which exhibit no such proofs, but on the contrary hold out every appearance of owing their origin to volcanoes or to some other mode of igneous action; and in every part of the world, and among strata of all ages, there occur evidences of such action so abundant, and on such a scale, as to point out the volcano and the earthquake as agents which may285 have been instrumental in the production of those changes of level, and those violent dislocations which we perceive to have taken place. ”

“ The trappean rocks may, in a general classification, be considered as volcanic. It will be shown, hereafter, that they are the lavas of submarine volcanoes. They do not, however, occur in the form of lava currents, but in great tabular masses, generally between stratified rocks, or in the form of dikes. They are also entirely unconnected with cones or craters.
The trappean rocks occur more or less abundantly in all countries. ”

“ Many of the great volcanic mountains of the world began as submarine volcanoes. A crater first opened on the floor of the ocean, and lava escaping, was heaped up around the opening, until it emerged above the surface as an island. As we have seen, the island of Iceland is believed to have begun in this way. Such, too, in all probability, was the origin of Hawaii, Vesuvius, Etna, and Santorin.
But besides the volcanic mountains that were thrown up during the geological past, there are others that have been called into existence while man has been living on the earth. ”

“ The geographical range of hundreds of aquatic species would be thereby circumscribed, and that of hundreds of terrestrial plants and animals extended.
A line of submarine volcanos crossing the channel of some strait, and gradually choking it up with ashes and lava, might produce a new barrier as effectually as a series of earthquakes; especially if thermal springs, charged with carbonate of lime, silica, and other mineral ingredients, should promote the rapid multiplication of corals and shells, and cement them together with solid matter precipitated during the intervals between eruptions. ”

“ Ocean volcanoes, and especially submarine volcanoes, affect both the temperature and the composition of the sea-water. Both the increase of temperature and the solution of volcanic gases increase the capacity of the water for mineral matter, and both the change in temperature and composition affect the life of the adjacent waters. The destruction of life during eruptions occasions the generation of the products of organic decomposition, and these stimulate further chemical changes. The diffusion of affected waters occasions chemical changes wherever they go. ”

“ It is not necessary, in order to prove the eruptions to have been submarine, that organic remains should be found in the tuffs or between them. If the volcanic ejections are intercalated among strata which elsewhere can be proved to be marine, their discharge must obviously have taken place under the sea. ”

“ It is not possible, among the representatives of former geological periods, to point to any rocks that can be fairly regarded as having issued from great submarine fissures, and it is therefore fair to conclude that no such great outbursts of the volcanic forces take plane at the present day on the deep ocean-floors. ”

“ When, as occasionally though not often happens, the effects of a submarine eruption are observed during the disturbance, it is seen that the surface of the sea is violently agitated, with copious discharge of steam, the water passes into a state of ebullition, perhaps throwing up huge fountains; shoals of dead fishes, with volcanic cinders, bombs and fragments of pumice, float around the centre of eruption, and ultimately a little island may appear above sea-level. ”

“ These tuffs, and the associated trappean rocks, must not be compared to lava and scoriæ which had cooled in the open air. Their counterparts must be sought in the products of modern submarine volcanic eruptions. If it be objected that we have no opportunity of studying [p.389] these last, it may be answered, that subterranean movements have caused, almost everywhere in regions of active volcanos, great changes in the relative level of land and sea, in times comparatively modern, so as to expose to view the effects of volcanic operations at the bottom of the sea. ”

“ The absence of cones and craters, and long narrow streams of superficial lava, in England and many other countries, is principally to be attributed to the eruptions having been submarine, just as a considerable proportion of volcanoes in our own times burst out beneath the sea. ”

“ At the same time, when we reflect to what a considerable extent the bottom of the great ocean basin is dotted over with volcanic cones, rising often solitary from profound depths, we can understand how large a proportion of the actual eruptions may take place under the sea. The foundations of these volcanic islands doubtless consist of submarine lavas and fragmentary materials, which in each case continue to accumulate to a height of two or three miles, till the pile reaches the surface of the water and appears above it. ”