Krakatoa

by Simon Winchester

  Clouds of sulphur-dioxide gas, usually released during eruptions, choke and poison their victims. Clouds of carbon dioxide suffocate them. Clouds of hydrochloric acid gnaw away at their lungs. The torrents of volcanic mud and water slurry that course down the sides of certain volcanoes and that have the Javanese name lahars (since there are so many such flows running down the sides of Javanese volcanoes – though not, as it happens, on Krakatoa) carry victims miles away, and drown and bury them.

  Sometimes secondary events can prove fatal. In 1985 a small eruption of a Colombian volcano called Nevado del Ruiz melted a glacier near the summit: the resulting river coursed down a valley that was quite unused to such huge flows, and the mud sea that was eventually created drowned an entire village below, killing 23,000 people. There are still more obscure risks: for example, volcanoes that erupt beneath glaciers – which tend not to have too many people living near them – produce sudden floods of melting ice, which have recently been given the exotic Icelandic name jökulhlaups. These can also prove fatal.

  However, of all the victims whose deaths can be attributed directly to volcanic activity during the last 250 years, fully a quarter are now believed to have died – drowned or smashed to pieces – as a result of the gigantic waves that were created by the eruptions. The entire Minoan civilization on Crete was supposedly wiped out in 1648 BC when volcanic tephra from the eruption of Santorini – or, much more probably, the tsunamis thrown up by the eruption – destroyed the palaces at Knossos. More than 10,000 people died in 1782 in the waves that were created by an avalanche of volcanic debris that hurtled into the sea from Japan's Mount Unzen. In 1815 a similar number of Javanese died when Tambora exploded, sending pyroclastic flows raging into the ocean, with tsunamis radiating out in all directions and inundating the coast.

  Careful study of the records for the last two and a half centuries has come up with a total of some ninety tsunamis for which volcanoes alone can be held responsible – and the greatest of these by far was the 1883 eruption of Krakatoa. About 35,500 men, women and children died as victims of the two gigantic waves that accompanied or were caused by the death throes of this island-mountain, and they account for more than half of all those in the world who are known ever to have died from waves caused by an erupting volcano. So this should be remembered well: it was neither fire nor gas nor flowing lava that killed most of the victims of Krakatoa. All but the thousand who were burned in Sumatra by the immolating heat of newly made ash and pumice and scalding gases died by the primary agency of water.

  During the eruptive days back in late May the state of the sea was certainly noticed, but was never once reported to be the cause of any undue alarm. The hopper Samarang noticed a swell powerful enough to lift her screw out of the water; the lighthouse keeper saw the surface of the Strait turn suddenly white; the rudder of the Bintaing, another small hopper, swung around and hit her own hull with a mighty clang when a freak wave caught her. But that was about all: the eruption in its opening stages was about ash falls and noise and that seven-mile-high column of coiling smoke. The ocean seemed to prefer not to become involved.

  But three months later matters were very different. The way that Krakatoa's immense outpouring of thermal energy was converted into mechanical energy – for this conversion is what essentially determines both the immensity and the enormity of any volcanic eruption – was altered. The noise was there, on an extraordinary scale. The expulsion of material high into the sky went on, both in gigantic amounts and for a very long time. But most of the mechanical energy went into the enormously difficult task of moving the ocean – movement that, once started and given additional shoves from behind, can become one of the most powerful natural forces imaginable.

  In August the state of the sea was something noticed by all. Right from the beginning, when Telegraph-Master Schruit took his lunch and strolled out on to the hotel veranda to first see the column of smoke, it was the strangely erratic motion of the sea that most alarmed him. On the far side of the Strait, in Ketimbang, Monsieur Contrôleur Beyerinck too was astonished by the punishment his town's little dock was having to take from the curiously restless waters. The ships out in the Strait – the Loudon, the

  A classic wall-of-water tsunami generated by only the most moderate of earthquakes on Krakatoa.

  Marie, the Charles Bal – all reported on the state of the sea. For them it was not so serious, as waves at sea are less dangerous to a ship than waves close to land. The electricity in the air and the rain of flaming rocks from the sky were quite dangerous enough.

  As darkness fell, so the sea became ever more furious. At 7 p.m. on the Sunday, Beyerinck saw small boats being tossed about. At the same time on the Javan side, Schruit found that his telegraph cable had been snapped by the mast of a schooner tossing on the waves. Between 7 p.m. and 9 p.m. several houses close to the seafront in the small town of Tyringin, well to the south of Anjer, were reported destroyed and swept away.

  At about 7.30 p.m. a quarry near Merak, where dozens of Chinese labourers were hewing out stone * for the new Batavia docks, was then inundated, and the camp where the workers slept was washed away: they may have been the first casualties of what was to be a long and mortally expensive night. But now there was a lull: though a village five miles out of Anjer was reported to be submerged at 10 p.m., by midnight the sea was glass-smooth once again; and at 1 a.m. on the Monday morning Schruit, still trying feverishly to repair his severed cable (he eventually failed), noticed only small oscillations in the surface of the sea close to where the Anjer canal debouched into it.

  Then at 1.30 a.m. one almighty wave is reported to have rushed up the long funnel of Lampong Bay to Telok Betong, where it ripped through and ruined several houses. Although it was clearly highly destructive, and though the time of its occurrence seems to be accurate, having been cross-checked with other witnesses (not least the servants of Beyerinck, sheltering with his family in their hilltop cottage), this one wave appears to be something of an aberration – far larger than its predecessors but unrelated to any particular event at the volcano. It was indicative, however, of what was to come.

  The greatest and most terrifying volumes of water began moving in concert with Krakatoa's four culminating explosions – the first eruptive paroxysm being timed, as we have seen, at 5.30 a.m. It was as though then something deep within the mountain had begun a series of low-frequency pulsations, the sea moving back and forth in time with each pulse, and the amplitude of these movements becoming greater and greater, the volume, as it were, of the waves becoming stronger and stronger with each sequence of pulses. The four major tsunamis that were caused by, or were coincident with, these giant volcanic explosions then hit the shores like planet-sized wrecking balls, the effects all unimaginably and fatally destructive.

  The destructive capacity of a great wave can be calculated, with difficulty, from a mess of competing and combining features, including the configuration of the shoreline, the funnelling effect of cliffs and headlands, and the depth of the coastal waters. It seems from the various eyewitness reports that what was most impressive about the waves that struck the shores of Java and Sumatra that morning was their sheer size – the high and unstoppable moving walls, the majestic volume of hundreds of billions of tons of roiling, thundering, foaming green water.

  The last four great explosions of Krakatoa's life took place at 5.30 a.m., 6.44 a.m., 8.20 a.m. and, finally and most terrifically of all, at 10.02 a.m. – all of these well-chronicled moments being recorded in Krakatoa Time, which (because each local Dutch administrator still set his official watch according to when the sun rose and set and reached its noontime peak in his own district) was in those days 5 minutes and 42 seconds behind what the capital's civil servants regarded as Batavia Standard Time. The energy that was released in these eruptions was transformed into a variety of violent effects. There were massive expulsions of rock and ash and gas. There were torrents of heat, searing and welding together everything around them. There we
re sounds – bangs, cracks, thunderous roars, shattering low- and high-frequency noises – that were so loud they could be heard thousands of miles away. Seismic shocks were triggered that caused buildings 500 miles away to rock on their foundations.

  And the eruptions also produced two kinds of shock waves. One was a wave that passed invisibly through the air, a sudden burst of pressure that bounced around the world, and was recorded as doing so, moreover, a remarkable seven times. These air waves – which recorded as pressure spikes at the Batavia gasworks, ninety miles to the east – radiated outwards from Krakatoa very fast, at what was an easily calculated velocity of about 675 mph. They were recorded as reaching Batavia at 5.43 a.m., 6.57 a.m. and (there seems, curiously, to be no firm record of any air wave resulting from the third explosion) at 10.15 a.m. respectively, Batavia Standard Time. (These events took place before the invention of time zones, either in the East Indies or anywhere else in the world. This, taken together with the dubious accuracy of many of the mechanical clocks of the day, the absence of the coordinating abilities of radio, which had of course not quite yet been invented, and the wide range of anecdotal reports from frequently panicky eyewitnesses, makes it tricky, though not entirely impossible, to construct a firm chronology of what took place in the aftermath of the eruptions.)

  The other shocks, considerably more ‘complex in the way they moved, of much shorter duration but of equally extraordinary geographical spread, involved the disruption of the surrounding sea-water. Sea-borne waves in general move much more slowly: in the relatively shallow waters of the Sunda Strait probably at an average speed of about 60 mph. * However the Krakatoa tsunamis were forged, it would take one of them about thirty minutes from the moment of eruption to travel to the closest point on the mainland.† And it would be thirty-seven minutes before the wave was close enough to the town of Anjer for the people there to see it, to recognize just what it was that was bearing down on them and to start – a fairly, but not entirely futile, gesture – to try to outrun it.

  It would take a further fifteen minutes for a great wave like this to seek out and destroy the quarries in Merak in the north, and drown all the Chinese workers there (as it did). It would take seven minutes fewer to flatten and wipe out all of Tyringin in the south (as it did also). And it would be one hour and one minute * before the same wave, slowing itself down but building itself up all the while, would reach all the way up to the head of Lampong Bay and, as it was equally sure to do, wreak havoc in the attractive little south Sumatran town of Telok Betong.

  The coastlines of Sumatra and Java are, like any coastlines, made hugely complex by all the inlets and island-shadowed estuaries, bays and peninsulas, rocks and reefs. The way that an inrushing wave behaves as it courses towards the shore is only vaguely understood – making it somewhat challenging to try to work out from the survivors' tales which wave actually struck and destroyed each affected town, village, kampong and home on the edges of the two great East Indian islands.

  Which wave was it that killed the vast majority of those 36,000 who were lost?

  Was it ‘the low range of hills rising out of the sea' that was seen, chillingly, by that elderly Dutch pilot in Anjer at dawn? ‘The sight of those receding waters haunts me still,’ he was to write later, since for him this was the killer wave, without doubt. ‘As I clung to the palm tree… there floated past the dead bodies of many a friend and neighbour. Only a mere handful of the population escaped. Houses and trees were completely destroyed, and scarcely a trace remains of where the once busy, thriving town originally stood.’

  Or was it the climax of all that terrible agitation of the sea that compelled Mrs Beyerinck across in Ketimbang to demand that her husband and family flee for the hills and the safety of high ground? Was it the ‘giant black wall of water’ that roared into Telok Betong at 7.45 a.m., picked up the gunboat Berouw as though it were a child's bathroom toy and dropped it in the middle of the Chinese quarter of town? The same wave that stranded the government's revenue cutter, and smashed all the local prahus and scattered the fragments of their hulls about like so much confetti?

  Could it have been one of the ‘four waves’ supposedly seen that morning by an engineer named R. A. van Sandick? He was a passenger aboard the Gouverneur-Generaal Loudon – the steamer which, it will be remembered, was unable to dock at any of the quays in Lampong Bay because of the raging surf. The waves, which came in at tremendous speed sometime between 7.30 and 8.30 a.m.

  … destroyed all of Telok Betong before our eyes. The light tower could be seen to tumble; the houses disappeared; the steamer Berouw was lifted and got stuck, apparently at the height of the cocoanut trees; and everything had become sea in front of our eyes, where a few minutes before Telok Betong beach had been. The impressiveness of this scene is difficult to describe. The unexpectedness of what is seen and the tremendous dimensions of the destruction, in front of one's eyes, make it difficult to describe what has been viewed. The best comparison is a sudden change of scenery, which in a fairy tale occurs by a fairy's magic wand, but on a colossal scale and with the conscious knowledge that it is reality and that thousands of people have perished

  The tide-meter at Jakarta registers a sudden swell at 12.36 p.m., two and a half hours after the eruption – showing how relatively slowly tides move, compared to the fast-spreading barometric pressure wave recorded at the gasworks.

  in an indivisible moment, that destruction without equal has been wrought…

  Or was it perhaps the wave that struck Merak at 9 a.m. – the wave that drowned all but two of the town's 2,700 inhabitants? An accountant named Pechler who somehow survived by running before it, climbing further and further uphill until he was beyond range, certainly would imagine this tsunami to be immeasurably vast: it destroyed stone buildings that stood on top of a hill later measured at 115 feet high; it drowned all thirteen Europeans who lived there and who had had good reason to feel secure, surrounded as they were by walls of heavy masonry on the summit of a good high hill. But the wave displayed all the insouciance of its great power; and at the time it roared over, submerged and then wrecked these mansions it was towering above them by a good twenty feet meaning that whether what Pechler saw was the wave or not, it was at least 135 feet high, formidable in its terror. It drowned everyone in the town below, and when the waters receded almost everything in the town was either smashed beyond recognition or swept clear away.

  Or yet again, might the great wave have been the one that was recorded when Merak was savaged once more, at 10.30 a.m.? A Dutch contrôleur named Abell, on the road to Batavia with his wedono * to report to his superiors details of tragic happenings yet further down the coast, looked around to see ‘a colossal wave’ roaring up the shore. It was, he said later, taller than the tallest palm tree he could see – a wall of water that no one caught by it could possibly have survived, something so dreadful it was quite beyond nightmares. Might this have been the one?

  The answer on this occasion is probably yes. In fact, almost without a doubt, however compelling and awful the accounts of eyewitnesses to the other tsunamis of that dreadful morning may be, this last was indeed the one, the real killer wave. It happened at what seems to have been the correct time – with a travel speed of 60 mph, its arrival at Merak at 10.30 would put its time of origin at Krakatoa at almost exactly ten o'clock, which is the moment of the culminating, self-destroying explosion.

  Most crucially, this one wave is recorded as having hit with extraordinary destructive power, a short while either before or later than the Merak 10.30 a.m. arrival, at all of the population centres of the west Java and south Sumatra coast. ‘An immense wave inundated the whole of the foreshores of Java and Sumatra bordering the Strait of Sunda,’ reported a contemporary study, ‘and carried away the remaining portions of the towns of Tjirin-gin, Merak and Telok Betong, as well as many other hamlets and villages near the shore.’

  Its arrival was also recorded on the well-armoured tide-meter in Batavian Harbour – at
12.36 p.m. A wave so powerful as to give an almighty jolt to that tide-recorder would have to have been enormous indeed. It would also have had, if travelling at 60 mph, to have begun its journey some two and a half hours beforehand. This means, in other words, that it would have originated at a few minutes past ten in the morning. Undoubtedly, from all the evidence, this too was Krakatoa's most colossal wave, the biggest consequence of the biggest and final explosion. It was a wave so enormous and so powerful that it turned out to be the grimmest of grim reapers, the terrible climax to a long and deadly day.

  ‘Everyone was frozen with horror,’ wrote the Resident of Lampong, Mr Altheer, of the moment when he heard the explosion, just after ten on that Monday morning. He well knew, from what had already happened disastrously three or four times before during the previous twenty hours, just what to expect: another tidal wave, probably much larger than before since this was so great an explosion, would now come racing out from the island, and it would arrive within minutes. That is, of course, had there been an island: Altheer had no means of knowing that Krakatoa was no more, having just been blown to oblivion.

  In the event the wave reached Telok Betong at 11.03. One anonymous European, writing some days later in a Batavia newspaper, was down on the town's shore, helping the local people who had already had their houses wrecked by the morning's earlier onslaughts from the sea. He was just lifting a huge wooden beam from on top of a trapped man, when he heard a scream. He looked up and saw a tall front of water rearing up and rushing towards him at a barely believable speed. There was a thunderous noise as it hit the beach and began rushing, crashing upwards through the town.