On the adjacent land are volcanic cones; some active, some slumbering, and others dead. It is recorded that Krakatoa itself was active in , and that voyagers in the vicinity encountered in that year a great storm and an earthquake at sea, accompanied by most frightful thunders and cracklings. Mention was also made of a strong sulphur atmosphere and of large quantities of pumice floating on the sea.
Since that time the island had been at rest, and was noted by travelers chiefly for the beauty of its tree-clad slopes, the first verdant spot to greet the eye after long weeks at sea.
So far as is known, the earliest indication of any subterranean disturbance was felt at Batavia, eighty miles distant, on the 20th of May, ; and it is a remarkable fact that while the commotion about to be described was taking place at Batavia, nothing unusual was noticed at Anjer, but twenty-five miles away, nor at Merak, thirty-five miles distant from Krakatoa, although from both places there is a clear outlook to that island.
In the forenoon of the 20th of May the inhabitants of Batavia were startled by a dull booming noise, followed by a violent rattling of doors and windows. Whether this proceeded from the air or from below was a matter of doubt, for unlike most earthquake shocks the quivering was only vertical.
The director of the observatory in Batavia reported the next day that no increase of earth magnetism accompanied the tremblings, and that a suspended magnet with a registering apparatus gave no indications of the slightest horizontal oscillations. An instrument maker in the town stated that on a pendulum in his shop only vertical trillings were observable, at a time when the windows and glass doors were rattling in so violent a way as to render conversation a matter of no little difficulty.
Nowhere do there seem to have been observed any shocks of a true or undulatory earthquake. Another curious circumstance was that at midday at some spots in the city no vibrations were perceived, while in the surrounding buildings they were distinctly experienced. It was a natural conclusion, however, that an alarming volcanic eruption had taken place; but it was impossible to localize the direction of the sounds, and at the observatory there were no instruments for making such determinations.
The tremblings continued throughout the day and during the forenoon of the 21st. A thin sprinkling of ashes fell at Telok Betong and at Semangko, in Sumatra; whence the ashes came, no one could tell.
At Buiteuzorg, thirty miles south of Batavia, the same phenomena were observed; while in the mountains farther to the southwest they were even more pronounced. By this time general opinion had ascribed to the west or northwest the direction whence the movements were proceeding. Krakatoa itself was mentioned, but some of the mountains in Sumatra were considered more likely to be the seat of disturbance. On the evening of May 21st smoke was seen issuing from Krakatoa, and on the 22d it was evident that the volcanic vent was at that place.
Shortly afterward the vibrations in Batavia ceased. During the next eight or nine weeks the eruption continued with great vigor, ejecting masses of pumice and molten stone, and volumes of steam and smoke. Although the prevailing monsoon carried to the westward the greater part of the matter thrown out, a cloud of lighter particles rose higher, and, encountering an easterly current of air, some of the dust fell on the island of Timor, twelve hundred miles distant.
During these weeks vessels passed through extensive fields of pumice spread over the surface of the sea. The soundings at the spot reached two thousand fathoms. It is known that a centre of volcanic disturbance exists in the Keeling Atoll, situated six hundred miles west by south from the mouth of the strait; and it is also known that pumice ejected from the sea bottom rises to the surface.
The currents of the Indian Ocean will show that any flotsam in the region between west and south of Java Head in that longitude could be drifted to the locality in which it was observed in the month of July. In a paper read before the Royal Geographical Society, Mr. Forbes suggested that the sounds heard in Batavia on the 20th of May, which were unnoticed at places so near Krakatoa as Anjer and Merak, and which would be inexplicable if they really originated there, were the result of a submarine eruption in the Indian Ocean, somewhere southwesterly from Java Head; and that the tremors were propagated thither, perhaps, by continuous strata connecting the locale of the outburst with Batavia, Buitenzorg, and more especially with the hills to the southwest, where the manifestations were so distinctly perceived.
If such a submarine outburst did take place, Mr. Forbes suggested that somehow the orifice very soon became blocked after a great inrush of water had taken place, which, becoming transformed into steam under enormous pressure, shaped its course for the nearest old earth scar, and found vent in Krakatoa by an offshoot, probably, of the funnel of the eruption of That such large lumps of pumice should be carried westward seven hundred miles into the Indian Ocean does not seem probable, especially as the earlier outbursts were not of very unusual vigor, for no pieces of any size are reported to have fallen on the neighboring coasts of Java and Sumatra; even after those of August, no ship farther off than one hundred miles speaks of the fall of any but the finest dust and sand.
On the 21st of August the volcano increased in activity. A ship reported being unable to venture into the strait on account of the great shower of pumice and ashes. On the afternoon of the 26th there were violent explosions at Krakatoa, which were heard as far as Batavia.
High waves first retreated, and then rolled upon both sides of the strait. During a night of pitchy darkness these horrors continued with increasing violence, augmented at midnight by electrical phenomena on a terrifying scale, which not only enveloped the ships in the vicinity, but embraced those at a distance of ten to twelve miles.
The lurid gleam that played on the gigantic column of smoke and ashes was seen in Batava, eighty miles away. Some of the debris fell as fine ashes in Cheribon, five hundred miles to the eastward. On the morning of the 27th there was a still more gigantic explosion, heard in the Andaman Islands and in India, which produced along both shores of the strait an immense tidal movement, occasioning that great loss of life recounted in the daily press.
The matter expelled rose to an elevation so tremendous that, on spreading itself out, it covered the whole western end of Java and the south of Sumatra for hundreds of square miles with a pall of impenetrable darkness. Abnormal atmospheric and magnetic displays were observed, compass needles rotated violently, and the barometer rose and fell many tenths of an inch in a minute.
Between ten and twelve o'clock in the forenoon of that day the subterranean powers burst their prison walls with a terrific detonation, which spread consternation and alarm among the dwellers within a circle whose diameter lay across nearly three thousand miles.
Strombolian explosions. Photos of strombolian eruptions. Ijen volcano photos Ijen volcano in East Java is famous for its turquoise acid crater lake and the large sulfur deposits that are being mined by local workers. At night, the scene is illuminated by ghostly blue flames, as sulfur ignites.
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Use of material: Most texts and images, in particular photographs, on this website are protected by copyright. Further reproduction and use of without authorization is usually not consented. If you are not sure or need licensing rights for photographs, for example for publications and commercial use, please contact us. At some point in the future, Anak Krakatoa will erupt again, generating more tsunamis. Since it is difficult to predict exactly which areas of the Sunda Strait will be affected, it is of paramount importance that residents in coastal villages are well aware of the danger.
An advanced early warning system could be installed. It would involve tide gauges to detect an increase in water levels, satellite imagery and drone mapping, and a tsunami numerical model run in real time.
When this system triggered a warning, it would be fed direct to residents who live in the coastal belt. Until such a system is in place, it will be vital to get the local community involved in disaster risk management and education.
It is also about educating people so that they feel psychologically healthier, more resilient and less anxious about facing the mega tsunamis of the future.
I have previously highlighted two examples of proactive community participation in disaster-prone villages in the UK and Japan. In both cases, residents know how to act in case of a natural disaster without depending on the authorities. It is certain that the decimation of the land and deaths could be reduced if the local communities are well prepared for natural disasters like tsunamis.
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