Mud volcano

“ They extend over a very large area, and are exceedingly numerous. The cone of one of them is no less than four hundred feet high, and the crater at the top is ninety feet in diameter. The mud in the crater is quite liquid, and is constantly disturbed by bubbles of gas, and occasionally by jets of the mud itself.
More familiarly known is the mud volcano of Macaluba, near Girgenti, in Sicily. It is situated in a country much impregnated with sulphur and other inflammable matters. ”

“ Further destruction is also caused by large streams of mud that rush down the slopes of the mountain, or by huge waves set up in the ocean. If the volcano is situated, as most volcanoes are, near the coast, the showers of ashes and falling stones may set fire to vessels in the neighborhood, or the progress of such vessels may be seriously retarded by layers of ashes or pumice stone that float on the surface. Sometimes these layers are so thick as actually to bring ships to a complete standstill.
It must not be supposed that volcanoes are in a constant state of eruption. ”

“ There is a gap in the hills; the trail skirts around one side, and behold, a vast, unbounded plain lies before us, stretching to left and right as far as the eye can see.
But what is this strange sight? On our right, barely a half of a mile from the road, is a gigantic mound. Its presence there, rising abruptly out of the mathematical flatness of the plain, seems ridiculous, absurd, uncanny. It gives the impression of having been just dropped from the sky. It is a mud volcano—an uncommon sight, and formed by the ejection of sand under pressure from below [Pg 168] the surface of the earth. ”

“ Java likewise contains a remarkable mud volcano. When viewed from a distance, there are seen to rise from it large volumes of vapour, like the spray from the billows dashing against a rocky shore, and there is heard a loud noise like distant thunder. On a nearer approach, the source of these phenomena is seen to be a hemispherical mound of black earth mixed with water, about sixteen feet in diameter, and which at intervals of a few seconds is pushed upwards by a force acting from beneath to a height of between twenty and thirty feet. ”

“ The cog railway begins at Leon at an altitude of 5300 feet and continues to Volcan, rising 1500 feet in a distance of eight miles. At Volcan there is supposed to be a mud volcano, but, as was pointed out some years ago by Mr. O’Driscoll in the “Geographical Journal,” there is no volcano at all. It is simply a mud avalanche, that comes down after unusually heavy rains from the rapidly disintegrating hillside.{76} Although not a volcano, it is nevertheless a difficult problem for the engineers. It has already completely submerged a mile or two of track more than once. ”

“ Volcanic Rain and Mud.—The condensation of the vast volumes of steam exhaled during an eruption produces torrents of rain, which, mingling to a greater or less extent with the volcanic ashes, forms a hot muddy stream known in Italy as lava d'acqua and lava di fango, and in South America as moya. Deluges of such mud-lava may rush violently down the mountain-side and spread over the neighbouring country with terribly destructive effect, whence they are greatly dreaded by those who dwell at the base of a volcano. ”

“ This phenomenon is associated in all climates with the close of a volcanic eruption. As during the eruption the cone of ashes is generally enveloped in cloud, and as it is in its immediate vicinity that the rain is most violent, torrents of mud are seen to descend from it in all directions, which the terrified husbandman imagines to consist of waters which have risen from the interior of the volcano and overflowed the crater ”

“ But, destructive as are the eruptions of the volcano when it belches forth ashes, cinders, and lava, it is even more so when its terrific operations are followed by deluges of water and avalanches of mud, carrying along with them immense blocks of ice and rock to great distances, causing death and devastation all along their course. Such an eruption took place in 1877, and, so great was the velocity of the angry flood, that it swept the plain with the momentum of an express train, carrying before it bridges, buildings, and everything that stood in its path. ”

“ One of the most curious productions of a volcano is mud. The aqueous vapour emitted by the crater being condensed by the cold atmosphere, heavy rains are produced, which, falling upon the volcanic dust on the sides of the mountain, form a current of mud, generally called aqueous lava, which is more dreaded by those dwelling in the vicinity of a volcano than a stream of melted lava. ”

“ Daubeny has pointed out that the mud volcanoes of this class that occur in the neighborhood of Sicily are due to the slow burning or oxidation of beds of sulphur.
Mud volcanoes which eject hot mud by the force of eruption of steam, which occur in volcanic districts, are of volcanic origin. They are caused by the passage of hot water and steam through beds of volcanic rock such as tufa, or hardened volcanic mud and other volcanic products. The hot water or steam raises the temperature of the mud through which it passes to the boiling point. ”

“ In the case of Volcanos, as we have already sufficiently conveyed, the hidden furnaces of the Earth find a vent for their surplus energies; and when this vent is once established, that is to say, when the active Volcano has begun to exist, it seems probable that there is little further upheaval, properly so called, of the surface. Nevertheless, Volcanos contribute largely to the formation of land by the vast accumulation of ashes, mud, and lava, which they vomit forth. The destruction of Herculaneum and Pompeii is a case in point. ”

“ Each eruption has left its traces written in ineffaceable characters on the slopes of the crater. Here was one of sand and mud, there one of lava and scoriæ ejected over the bed of mud. Then again an outpour of lava, and after that another of mud containing great boulders of granite burnt red and rendered friable.
"Imagination is roused," says M. A. Mazon, "at the thought of what must have been the scene when the volcano of la Vestide belched forth tempests of fire which agitated, upset, and shaped the soil of the Vivarais. ”

“ Through the stopping up of the vents, these mud eruptions are sometimes of explosive violence, and the friction of colliding stones with one another may set fire to the inflammable gas, producing a result still more closely resembling the fiery eruption of a true volcano. ”

“ From these small craters bubbles of gas arise from time to time; but at long intervals they become much more active, and throw up jets of wet mud to the height of nearly two hundred feet. This mud smells strongly of sulphur.
In the peninsula of Taman, near the entrance to the Sea of Azof, there is a group of mud volcanoes, from one of which there was a considerable eruption on the 27th of February 1793. It was preceded by underground detonations, and accompanied by a column of fire and dense vapour, which rose to the height of several hundred feet. The discharge of mud and gas was abundant. ”

“ Mud-volcanoes are found in Northern Italy near Modena, in Sicily near Girgenti, on the shores of the Sea of Azof and the Caspian, in Central America, and in other parts of the globe. The gas frequently escapes from them with such violence that mud is thrown into the air to the height of several hundreds of feet. Sometimes this gas is inflammable, consisting of sulphuretted hydrogen, hydrogen, or some hydrocarbons, and these gases occasionally take fire, so that true flames issue from these mud-volcanoes. ”

“ The lightning flashes in all directions from the black canopy overhanging the mountain, the perpetually rolling thunder adds its loud voice to the dreadful roar of the labouring volcano, while torrents of rain, sweeping along the light dust and scoriæ which they 69carry down with them from the air, or meet with on their way, produce currents of mud, often more dreaded than streams of lava, from the far greater velocity with which they move. ”

“ The mountains composed of volcanic materials, but which have lost through denudation the external form of volcanoes, are still more numerous, and the smaller temporary openings which are usually subordinate to the habitual vents that have been active during the periods covered by history and tradition, must be numbered by thousands. There are still feebler manifestations of the volcanic forces—such as steam-jets, geysers, thermal and mineral waters, spouting saline and muddy springs, and mud volcanoes—that may be reckoned by millions. ”

“ Such a displacement is not warranted by the geological facts; for while volcanic eruptions occur frequently in localities where the strata are much displaced, they also occur where there has been no displacement of any moment since the Cambrian age.
A singular class of phenomena is found in the so-called mud volcanos which have always been a great puzzle, but which are easily explained by this cause. We find them in Central America and in Java, and the remarkable case of Bandai San, in Japan, is well remembered. These volcanos must have their origin at less depth than the lava eruptions. ”

“ The stone, ashes, and mud ejected during eruptions are even more destructive than the rivers of lava. In 1851 Tomboro, a volcano on the island of Sumbava, cost more lives than fell in the battle of Waterloo. ”

“ Mud volcanoes, after the first violent explosion of fire, which is not, perhaps, in an equal degree common to all, present to the spectator an image of the uninterrupted but weak activity of the interior of our planet. ”

“ On the other hand, secondary manifestations of vulcanism were everywhere abundant. The extraordinary prevalence and violence of earthquakes throughout the ancient world, their effect upon the popular mind, and the extent to which even historical events were influenced by them, are facts too well known to require comment. Frequent references in literature to mud volcanoes, solfataras, fumaroles, sulphur springs and allied phenomena reveal a lively curiosity in these matters, and a growing tendency to associate them with volcanic action. ”

“ The existence of heated materials at no great depth from the surface is indicated by the outburst of gases and vapours, the formation of geysers, mud-volcanoes, and ordinary thermal springs. But as the underlying rocks cool down, the issuing jets of gas and vapour lose their high temperature and diminish in quantity, the geysers and mud-volcanoes become extinct, and the thermal - 223 - springs lose their peculiar character or disappear, and thus all manifestations of the igneous energies in the district gradually die away. ”

“ Here were mud volcanoes, which some of the party visited, being carried there in bullock carts, and found them rather interesting, the volcanoes emitting mud instead of lava.
We arrived at a place near old Pagan at four in the morning, and never can I forget the spectacle presented from my stateroom window. There was total darkness, save where long lines of natives with lanterns, coming from the woods in every direction, were seen carrying boxes, bales, and baskets of freight to the shore. Once at the landing, the rush and commotion and waving of lanterns were truly Burmese. ”

“ As a matter of fact, the actual amount of damage - 282 - to life and property which is effected by volcanic eruptions is small. Usually, the inhabitants of the district have sufficient warning to enable them to escape with their lives and to carry away their most valuable possessions. And though fertile tracts are covered by loose dust and ashes, or by lava- and mud-currents, yet the sterility thus produced is generally of short duration, for by their decomposition volcanic materials give rise to the formation of the richest and most productive soils. ”

“ It is so hot that the gases are completely burned. However, you see smoke rising from the solid lava surrounding the lake, where the heat is not great enough to burn the gases. These come hissing up through fissures in the rocks, especially along the raised rim of lava that surrounds the lake. The hot flood undercuts this rim into caves of lava, just as the ocean digs out sand caves, and here the volcano gases accumulate under pressure, and rush out violently in white clouds."
"Do birds ever fly over an active crater?" ”

“ The most of the dust — all the coarser grains of it, at least — that is thrown up by these eruptions returns also by gravity, or is borne down by the torrential rain, to the region about the base of the volcano. It is only the remnant of water and of powdered rock that remains high in the air, like the wrack of a thunderstorm, to float far away from the point where it was hurled into the air. ”

“ It is a gentle ascent of only 200 or 300 feet from the rest house and the temples to the summit of the cone, first over a lava stream that looks as if it might have flowed but a little while before, then over a talus of lava, pumice and cinders, and finally over slippery, grey volcanic mud. At the top is the crater, a black, ragged, awful pit, roaring and steaming constantly. As one stands on the brink one looks down walls of roughly-stratified mud to a depth of 300 or 400 feet, where two round vents are continually rolling out masses of steam ”

“ During such eruptions, magma is shattered into tiny fragments (chiefly ash and pumice) and ejected thousands of meters into the atmosphere or even the stratosphere. Under the force of gravity, sometimes these fragments sweep down a volcano’s flanks at speeds of more than 100 kilometers per hour, mixing with air and volcanic gases to form pyroclastic flows. Rock fragments can also mix with water in river valleys to form lahars (volcanic debris flows and mudflows) that destroy everything in their paths.
Andesite and dacite magmas also erupt to form lava flows. ”