Island on Fire Page 6
Ambrose’s proposal drove straight to the heart of some of the biggest questions in science. Where did we come from, and how did we get here? How did our environment shape us, and how resilient were we in the face of disaster? Do we have any control over our destiny, or are we constantly subject to the whims of nature looking to wipe us out? Naturally, other researchers started looking for answers – mostly in India, which was smack in the path of Toba’s ashfall.
In southern India’s Jurreru Valley, a team of British and Indian scientists has found stone tools and other artefacts that they argue were made by Homo sapiens and date to both before and after the Toba eruption. If so, the discovery suggests that early humans were able to weather the eruption without too much trouble. Other researchers argue that perhaps Toba forced people to retreat to nearby refuges until conditions improved. Further north, in north-central India, environmental records show how the Toba eruption caused vegetation to shift from forests and woodlands to mainly open grasslands for at least a couple of centuries – a change that must have forced people to find something new to eat.
Toba’s eruption was crucial to the history of life on Earth. And it may one day make another intervention. The blast left behind a caldera 100 kilometres long and 30 kilometres wide, which is now the world’s largest volcanic lake. Modern measurements show that the bottom of Lake Toba is rising, perhaps because of magma filling the chamber beneath the legendary volcano. It is likely to be a few more hundred thousand years before Toba clears its throat again.
It won’t be nearly as long before another feared volcano goes off.
Today the Greek island of Santorini (or Thera) is a tourist’s paradise, with azure roofs and whitewashed buildings gleaming above the Aegean Sea. But Santorini’s tranquillity belies its fiery underbelly. It is one of a strand of volcanoes created as Africa’s tectonic plate slides beneath Eurasia, causing magma to rise from below.
Santorini most famously blew its top around 1600 B.C.E., during the Bronze Age. The eruption was so violent that it shattered the volcano and left behind an expansive caldera, like that at Yellowstone. But here, instead of being filled with aspen and bison, the caldera is filled with the waters of the Aegean. The islands known collectively as Santorini outline part of the caldera’s rim. The steep cliffs on which homes are perched underscore the eruption’s violence: the cliffs are composed of layer upon layer of volcanic ash that piled up hundreds of metres thick and then consolidated into rock.
Debris from this blast, usually called the Thera eruption, can be found all over the eastern Mediterranean. The eruption, rated a VEI of 6 or greater, would have sent tsunamis in all directions, drowning sailors and coastal villages. Some scholars have even linked the explosion to the decline of the mighty Minoan civilization, which thrived on and around the island of Crete. Remains of Minoan pots have been found buried beneath ash from Santorini, which does seem to support the idea that the Bronze Age eruption hastened the decline of the Minoans. But archaeologists don’t have a well-defined timetable for when particular events happened in this region, so it is hard to know for sure.
Recent eruptions have built up two small islands in the massive collapsed crater left behind by the Bronze Age eruption of Santorini, Greece.
Stories of the eruption must surely have survived in oral histories, however, and it’s highly plausible that, some 1,300 years later, Plato was thinking of these tales of Thera when he wrote about Atlantis – an island that sank beneath the sea, accompanied by flames and a shuddering of the Earth. In his Timaeus, Plato describes the place:
Now in this island of Atlantis there existed a confederation of kings, of great and marvellous power, which held sway over all the island, and over many other islands also and parts of the continent… But at a later time there occurred portentous earthquakes and floods, and one grievous day and night befell them, when the whole body of your warriors was swallowed up by the earth, and the island of Atlantis in like manner was swallowed up by the sea and vanished.
Of course, no one can be certain whether Plato was relaying a tale that had been passed down over generations and was based in fact, or simply speculating on a lost world. But a disaster such as the Thera eruption would not easily be forgotten.
Santorini has more to come. The volcano has been occasionally active since its Bronze Age blowout, and over the past few centuries small eruptions have built up two little islands in the caldera’s centre, named Palaea Kameni (meaning ‘old burnt island’) and Nea Kameni (‘new burnt island’). Greek authorities are worried enough about Santorini to have helped an international team of researchers to set up a monitoring system across the caldera. Global positioning system stations dotted around Santorini’s rim receive signals from satellites, which measure tiny changes in the stations’ elevation. Rises of just a few millimetres a year could indicate that a magma chamber beneath Santorini is beginning to inflate, like a person drawing in a big breath. This kind of ground deformation is often seen before a volcano erupts.
The stations captured such an inflation event starting in January 2011, with the ground rising 140 millimetres in 12 months. But volcanoes can uplift land without actually erupting; in the 1980s, the ground near Pozzuoli, Italy, rose nearly two metres, but the Campi Flegrei caldera below it did not erupt. Santorini’s inflation slowed to a near-stop in 2012, and it’s not clear whether the volcano plans to erupt anytime soon. Even if it does, geologists say, it won’t be anything like the scale of the Minoan eruption. It will probably be something like the eruptions of the 1950s: small and burbling and possibly building up new small islands. Santorini is not dead yet.
Neither is one of the world’s most notorious volcanoes: Vesuvius, the destroyer of Pompeii. This iconic mountain, which glowers over the city of Naples, belongs to one of Europe’s most active volcanic fields. Within a small geographic span lie the fiery fountains of Etna, the fuming peak of Stromboli, and the bubbling mud pots of the Phlegraean Fields – home to a supervolcano that exploded some 39,000 years ago.
Even among all this competition, Vesuvius is the grand-daddy of Italian volcanoes, and its eruption in 79 C.E. is the founding narrative for all disaster stories that followed. The catastrophe was captured in words by Pliny the Younger, who described the horror of the event and the death of his uncle, the polymath Pliny the Elder. Centuries later, archaeologists unearthed even more eloquent testimony in the form of Pompeii and Herculaneum, towns eerily entombed in layers of volcanic ash.
Vesuvius has been active for millennia. Gazing at the mountain, the ancient geographer Strabo recognized this violent history in the rocks: ‘One might infer that in earlier times this district… had craters of fire,’ he wrote. The historian Plutarch later wrote of the sky around Vesuvius as being ‘on fire’, and the poet Silius Italicus described the mountain ‘hurling flames worthy of Etna from her cliffs’. But in the years leading up to 79 C.E., nobody was paying much attention. Thousands of people lived obliviously on the gentle slopes around the mountain, where vineyards thrived in the fertile soil. Life seemed good.
On 23 August of that year, residents in Rome celebrated the annual Volcanalia festival, in an effort to appease the god of flaming mountains (or, perhaps, just to throw a good party). Apparently Vulcan wasn’t paying attention, because on the afternoon of 24 August, Vesuvius suddenly blew its top. Ash shot into the air, spreading quickly into a threatening cloud. In Pompeii, ten kilometres downwind, stones and ash began raining from the sky. People fled in terror as ash piled on the roofs of buildings, collapsing them. In less than a day, debris buried parts of the town as much as 1.4 metres deep.
Just after midnight, the pyroclastic flows began. These surges of hot rock and ash avalanched down the mountain’s western slopes. Herculaneum, just a few kilometres away, had no chance: the street grid funnelled the fiery flows directly into the heart of the town. People, animals, buildings – everything was incinerated. Unlike Pompeii, those in Herculaneum had practically no time to escape.
Ac
ross the bay to the west, two of history’s most famous scribes watched the scene with mingled fascination and horror. Pliny the Elder had been staying at his summer villa with his sister and her son, the 17-year-old Pliny the Younger. When Vesuvius exploded, the elder statesman apparently couldn’t believe his luck at having an opportunity to witness such a momentous eruption. He climbed to the highest point he could find and watched the ash cloud develop. Later his nephew recalled how they saw the plume grow into a shape ‘like an umbrella pine, for it rose to a great height on a sort of trunk and then split off into branches, I imagine because it was thrust upwards by the first blast and then left unsupported as the pressure subsided.’ This classic, umbrella-like shape forms when a volcanic ash plume hits winds going sideways in the upper atmosphere and spreads out. We now use the adjective ‘plinian’ for this type of ash cloud, after the man who first described it.
Pliny the Elder then decided to take a boat and look more closely at what was happening. His nephew wisely declined. Within hours the elder Pliny was dead, having collapsed on the beach where he had gone to check out the eruption. Two letters from the young man, written to a friend three decades later, describe the horror of the hours that followed:
We had scarcely sat down to rest when darkness fell, not the dark of a moonless or cloudy night, but as if the lamp had been put out in a closed room. You could hear the shrieks of women, the wailing of infants, and the shouting of men; some were calling their parents, others their children or their wives, trying to recognize them by their voices. People bewailed their own fate or that of their relatives, and there were some who prayed for death in their terror of dying. Many besought the aid of the gods, but still more imagined there were no gods left, and that the universe was plunged into eternal darkness for evermore… I could boast that not a groan or cry of fear escaped me in these perils, had I not derived some poor consolation in my mortal lot from the belief that the whole world was dying with me and I with it.
Yet even after such agonies, the story of Vesuvius in 79 CE faded into local memory. Its tale did not come to light until more than a millennium and a half later, when people began to realize that entire Roman towns lay buried beneath their feet. In 1592, a canal excavation near Naples uncovered what would be the first artefacts from Pompeii. Just over a century later, digs began in earnest when a prince bought some land in the area and, in the process of sinking a well, found a subterranean town. By 1738 much of Pompeii was unearthed. The finds were a remarkable glimpse into Roman life: mosaics, paintings and foods preserved as they were when Vesuvius entombed them. People were incinerated instantly as the ash congealed around them, forming moulds of their bodies at the moment of death.
This Roman fresco celebrating Bacchus, the god of wine, was unearthed at Pompeii, Italy. It shows Vesuvius before the volcano blew its top in 79 C.E.
Soon, Vesuvius became the laboratory in which leading ideas about volcanoes were forged, modified or rejected. A British government representative, Sir William Hamilton, lived in Naples from 1764 until 1800 and climbed the mountain time and again, bringing along any curious visitors he could entice to join him. He sent long reports of Vesuvius’s activity to London’s Royal Society, and even shipped back a couple of light-and-sound devices that displayed the mountain pouring forth streams of lava to the accompaniment of booming thuds. More than anyone before him, Hamilton brought Vesuvius into public consciousness beyond Italy.
Since 79 CE, Vesuvius has erupted more than fifty times. It has been silent since a small eruption in 1944, but those who know Vesuvius say it is only a matter of time. Volcanologists recently identified a zone, about eight to ten kilometres below the mountain, where seismic waves travel more slowly than usual. That zone could be a magma chamber slumbering away – for now. Chemical studies of erupted lava suggest that the stuff in the underground reservoir could be capable of immediately creating a massive eruption. Looming over a city of more than three million people, the volcano defined by Pliny may soon show the world what it did two millennia ago.
Our narrative now skips forward to a year much closer to modern times. In 1815, just a few decades after Laki cloaked much of Europe in a toxic fog, another deadly volcano sent its gaseous tendrils around the world. This time the culprit lay half a world away, in the volcanically restive islands of Indonesia. The VEI 7 eruption of Tambora is the greatest known to history. More than 70,000 people perished, the most known from any single eruption, many of whom sickened or starved as ash buried their rice fields. Further afield, millions shivered as the volcano spread its aerosols worldwide, chilling the planet and causing the famous ‘year without a summer’ of 1816.
Before Tambora blew, the central Indonesian island of Sumbawa was a tranquil and productive place. ‘Nature had poured its bountiful blessings on this island,’ wrote a pair of visitors in 1824, which ‘no matter how mountainous, is the proud possessor of the most extensive of plains and the loveliest of verdant valleys. Rice, beans and maize were plentiful, the forests provided wax and excellent timber… Coffee, pepper and more especially cotton were grown.’ Locals collected birds’ nests and salt to sell, and the island was famous for the quality of its horses.
Looming over all this bounty was the mighty peak of Tambora. At some 4,000 metres high, it was one of the tallest mountains in all of Indonesia and a landmark for sailors to navigate by. And there were plenty of sailors to see it: in the spring of 1815, Indonesia was still the Dutch East Indies, the ‘spice islands’ from which Europeans shipped back pepper, nutmeg and other fragrant commodities. Trade was thriving, and the waters around Sumbawa bustled with trading vessels, fishermen and pirates.
In the midst of all this activity, Britain had managed to wrest control from the Dutch and occupy the island of Java in 1811. In the capital, Batavia (today’s Jakarta), Thomas Stamford Raffles served as lieutenant governor. Raffles would be there to observe Tambora’s blast and collect accounts of the disaster from around the archipelago, building the best-yet documentation of the effects of a massive eruption.
Tambora had probably lain quiet for more than a millennium before it began half-heartedly spitting out ash in 1812. Then, on the evening of 5 April 1815, the mountain awoke violently. Ash and smoke began to rise, and explosions shook the ground. Thousands of kilometres to the west, in Batavia, Raffles thought a ship might be putting out distress calls and sent his troops to check. Further east, on Java, soldiers thought they heard cannon fire and marched out to look for attackers.
Five days later, in a colossal eruption unlike any ever witnessed, Tambora hurled smoke and ash even higher, perhaps as high as 40 kilometres. A local chief later described the scene to one of Raffles’s officers:
Three distinct columns of flame burst forth… and after ascending separately to a very great height, their tops united in the air in a troubled and confused manner… In a short time, the whole mountain… appeared like a body of liquid fire, extending itself in every direction. The fire and columns of flame continued to rage with unabated fury, until the darkness caused by the quantity of falling matter obscured it.
Floods of superheated gas and ash surged down the mountain’s sides, wiping out villages at its base. The flows plunged into the ocean, reacting with seawater and sending mighty ash plumes hurtling skyward. For three days, day turned to night. Wading through the ash-choked darkness, people could not see their hands held before their eyes. When the daylight returned, they were shocked to see that Tambora had lost more than 1,000 metres from its summit.
Death and destruction continued to rain down. Ash buried buildings, which subsequently collapsed under the weight, killing people sheltered there. A tsunami swept across northern Sumbawa, drowning villages. And the horror didn’t end when Tambora quietened down. Thick blankets of ash covered the rice fields, smothering crops. The once-bountiful island began to starve. Some people sold their children for bags of rice imported from other islands. Water contaminated with ash gave anyone who drank it rampant diarrhoea. Corpses beg
an to pile up by the sides of roads.
The 1815 eruption of Tambora drastically reduced one of Indonesia’s tallest peaks (photographed here by astronauts aboard the International Space Station).
With little way to make sense of such catastrophe, the locals turned to the spiritual for explanations. Soon a folk tale sprang up, in which the ruler of Tambora’s kingdom had slaughtered an innocent Muslim pilgrim. The volcano erupted, the story goes, as divine retribution for this violation. A local poem describes the shame:
Its noise reverberated loudly
Torrents of water mixed with ash descended
Children and mothers screamed and cried
Believing the world had turned to ash
The cause was said to be the wrath of God Almighty
At the deed of the King of Tambora
In murdering a worthy pilgrim, spilling his blood
Rashlessly and thoughtlessly.
The disaster didn’t end in Indonesia. The sulphur emitted by Tambora would go on to combine with water and produce acidic particles that spread around the globe, altering weather worldwide. By the following year temperatures had plummeted in western Europe and northeastern North America, earning it the nickname of ‘eighteen hundred and froze to death’. In early June, a cold front swept across the northeastern United States, such that snow fell in Albany, New York, and frost killed most of the apple fruit that had just finished blossoming. Unbelievably, hard frosts came again in July and August. The major crops of corn and hay failed, leaving little fodder for livestock to eat the following winter. Disheartened, many farmers struck out for what they hoped was better weather in the west, hastening the American migration westward.