Island on Fire Read online

  Even a relatively small pyroclastic flow can have devastating consequences, since they behave so unpredictably. Firebrands can detach from the main current and start secondary fires or currents nearby. And flows that are relatively dilute – that is, not carrying so much debris – can rush up steep slopes, or change direction quickly. It’s nearly impossible to tell just by looking at a pyroclastic flow which kind you might be facing.

  Then there’s the danger of ash and other rock debris (known collectively as ‘tephra’), which can overload the roofs of buildings, causing them to collapse. In many volcanic areas, buildings are reinforced to lower the risk, and people are educated to sweep their roofs clear of ash, or to evacuate if the ashfall gets too heavy to keep up with. Out in the open, you’re even more vulnerable. At Mount St. Helens, eighteen people were engulfed by tephra and asphyxiated by plugs of ash and mucus.

  Another risk from eruptions is the presence of large rocks moving at near-ballistic speeds. During the Mount St. Helens eruption, a man died from a rock that smashed into his car 16 kilometres from the main volcanic vent. Scientists, too, are not immune: at least twice on field trips after international volcanology meetings, researchers have been killed on visits to observe local eruptions. In Colombia in 1993, six scientists and three others died at Galeras volcano when a sudden explosion occurred as they were standing inside the inner crater. In Indonesia in 2000, two volcanologists died and five others were injured in much the same circumstances.

  For sheer unpredictability, though, almost nothing matches what can happen when an eruption creates a flood of water, mud and other material. Known as lahars or debris flows, these torrents often have the consistency of wet concrete, and can destroy everything in their path. Many of the world’s most active volcanoes are high mountains capped with snow and ice: when these erupt, the heat melts the ice and generates deadly lahars. In 1985, nearly the entire city of Armero, Colombia, was annihilated by mudflows coming from the eruption of the glacier-topped Nevado del Ruiz.

  Icelanders, of course, suffer glacial outburst floods as well, the jökulhlaups. The 1996 eruption at Grímsvötn drained a subglacial lake, sending a torrent rushing along a 50-kilometre path. The biggest flood ever measured at Grímsvötn, with some 40,000 cubic metres pouring out every second, it washed away a portion of Iceland’s crucial ring road and destroyed two bridges, including one nearly a kilometre long.

  Floods are not the only watery disasters linked to volcanoes. Under the right conditions, volcanoes have the potential for producing catastrophic tsunamis. Usually the sheer force of the explosion triggers underwater landslides that kick up massive waves that then race ashore. In 1792, a tsunami precipitated by a landslide during an eruption of Unzen may have washed away more than 10,000 people. After the 1815 eruption of Tambora, pyroclastic flows rushing into the sea generated waves more than ten metres high that killed at least 4,600. And most of the 36,000 deaths at Krakatau in 1883 probably came from a tsunami created when the volcano collapsed suddenly into the ocean.

  Multiple pyroclastic flows left their deadly traces down Unzen volcano, Japan, seen here in November 1991.

  Finally, there are the toxic gases. Killers such as carbon dioxide and hydrogen sulphide suffocate anyone unlucky enough to run into them, as at Lake Nyos. But volcanic gases don’t always kill right away. Prolonged exposure to them can cause severe health problems in people living near volcanoes.

  One of the best places to study such health hazards is at Kilauea, Hawaii, which has been erupting continuously since 1983. Perched on the southeast corner of what Hawaiians call simply the Big Island, Kilauea is one of the world’s best-studied volcanoes. MIT professor Thomas Jaggar started it all in 1912, when he employed prisoners from a nearby military camp to dig through six feet of pumice and ash to install seismometers on Kilauea’s steep caldera rim. This single observation post would later morph into the Hawaiian Volcano Observatory, the first long-term scientific effort of its kind.

  Jaggar was moved to act after 8 May 1902, the day when 30,000 people died in the eruption on Martinique. Hours earlier, 1,700 had perished on the nearby island of St. Vincent, in an eruption of La Soufrière. Jaggar was part of an expedition of scientists sent to document the damage from both Caribbean volcanoes. Horrified by what he saw, Jaggar was particularly upset by the fact that Martinique officials had made no efforts to warn people of the volcano’s danger. He thought scientists should do better.

  Thus was born the idea of a permanent observatory, to better understand the behaviour of volcanoes and develop ways of predicting eruptions. ‘If we could get… a properly endowed laboratory of the study of earth movements… we might be able in a few years to make earthquakes and volcanoes ordinary risks for insurance, and also succeed in preserving a great many human lives,’ Jaggar wrote in a San Francisco newspaper in June 1906, two months after an earthquake devastated that city.

  Jaggar spent a long time thinking about where he wanted to set up his observatory, and visited Japan, Alaska, the Caribbean and Italy before settling on Kilauea, which had the advantage of being on American territory and fairly easy to reach. Plus, he wrote, the Hawaiian volcanoes ‘are famous in the history of science for their remarkably liquid lavas and nearly continuous activity.’ By January 1912 the observation post was up and running.

  Today the Thomas A. Jaggar Museum and the Hawaiian Volcano Observatory perch together on Kilauea’s summit. This is very near the spot where Kilauea erupted explosively in 1790, in the deadliest eruption on any territory that would become part of the United States. Some one hundred warriors and their families were killed as they walked past the crater, during a great battle with another local chieftain. The thousands of visitors who stream through the museum and visitors’ centre every year are walking practically on top of this deadly spot.

  The museum conveniently overlooks a large crater, from which steam rises ominously and a bright red-orange glow can be seen at night. This crater, known as Halemaumau, is the legendary home of the Hawaiian fire goddess Pele. Her older sister, Namaka-o-kahai, was a goddess of the sea, and the two siblings fought constantly. Namaka-o-kahai eventually ran Pele out of their home, and the banished sister has since languished alone at the smoking summit of Kilauea. When Pele gets angry, she spits lava and hisses steam. Tradition has it that the only way to placate her is to leave small offerings, like the leis and other tokens often found dotting the trails around Kilauea.

  Since 1983 Pele has taken out her wrath at various spots along Kilauea’s huge, dome-shaped surface. In addition to the summit crater of Halemaumau, much of the action takes place along an eastern rift zone known as Pu’u O’o. Photographers congregate to capture glowing red lava plunging dramatically into the sea with much hissing and steaming. Other portions of the rift zone have also opened up over time, spilling lava into established communities and swallowing whole townships. Not that this keeps all Hawaiians away: brand-new homes have already cropped up on lava flows that stopped steaming just a few years ago.

  With people and eruptions so close together, it’s no wonder that Kilauea has become a favoured place for studying the health hazards of volcanoes. Hawaiians are familiar with the thick haze they call vog, or volcanic smog. When trade winds blow from the northeast, the vog often wraps around the Big Island from Kilauea and settles over the more densely populated western coast. When winds are variable or blow from the south, vog can spread all the way up the Hawaiian island chain, to Oahu (site of the capital, Honolulu) and beyond.

  Pele, the Hawaiian fire goddess. Note the rope-like lava that constitutes her hair.

  Near the active vents, vog is made mostly of sulphur dioxide droplets. Over time and at greater distances, those droplets react with sunlight and chemicals in the air to become more complex sulphur compounds, including sulphuric acid. Breathing in this stuff isn’t great for you: sulphur dioxide irritates the throat and nose, and aerosol particles can lodge in the lungs, aggravating asthma.

  Bernadette Longo, a
n epidemiologist at the University of Nevada in Reno, has looked at rates of asthma and other respiratory illnesses in people living on the Big Island, and found major hazards coming from Kilauea. Things got particularly bad after 2008, when the summit crater of Halemaumau began to erupt, disgorging about three times as much sulphur dioxide as before. Levels soared well above the World Health Organization’s 24-hour guidelines. Between 2004 and 2010, Longo found, the risk of respiratory illness went up dramatically for anyone living in vog-thick areas: asthma went up 222 per cent (579 per cent for children); acute bronchitis increased 73 per cent (444 per cent for children); and upper respiratory infections 83 per cent (234 per cent for children).

  Longo’s findings from Hawaii may be particularly relevant to Laki, and the many months during which Icelanders sucked its toxic gases into their lungs.

  After all, many of the deadliest volcanic phenomena were not a problem at Laki. There were no pyroclastic flows, killer jökulhlaups or powerful tsunamis. The eruption occurred relatively far from human settlement, and people in and around Klaustur could generally get out of the way of lava flows in time.

  Yet census figures show that Iceland’s 1783 population of 48,884 was reduced three years later to 38,363 – a loss of 22 per cent. Officially these deaths all resulted from famine. However, starvation may not explain everything. In particular, one underappreciated culprit may be the element fluorine.

  Sheep, horses and other mainstays of the Icelandic economy are vulnerable to a fluorine poisoning known as fluorosis. Among its earliest symptoms are the famous pointy ‘ash-teeth’ first noted after a seventeenth-century Hekla eruption. Icelandic farmers today still occasionally put bowls of water outside, to see if they catch any ash particles falling from a nearby or distant eruption; if any ash is detected, the farmers move the animals inside. Fluorine concentrations are actually highest in ash particles farthest from the eruption, since most of the element is carried by the finest-grained particles.

  More so than many eruptions, Laki was particularly rich in fluorine. Maureen Feineman, a geochemist at Pennsylvania State University, has studied the chemical composition of rocks formed during the 1783–84 eruption. Her work found that the magma that eventually erupted from the Laki fissure must have rested underground for some time, melting and mixing in some of the rocks surrounding the magma reservoir. That extra time sitting in the crust led to the absorption of increased levels of elements such as sulphur, chlorine and fluorine. With more of these volatile elements to start with, Laki was able to spit large amounts of them out.

  Fluorine poisoning occurs in people living near other volcanoes. In the Azores, people have contracted fluorosis from drinking water that circulated through fluorine-rich ash beds. In Vanuatu, where people collect drinking water on their roofs during rainstorms, up to 96 per cent of children living near the constantly de-gassing volcano of Ambrym display signs of dental fluorosis. In Iceland, too, fluorine would have settled on the ground and run into rivers from which villagers took their drinking water. At its peak, the 2010 Eyjafjallajökull eruption was showering the landscape with nearly 700 tonnes of fluorine daily.

  Even one of Iceland’s greatest heroes might have suffered from fluorosis. Egil, son of Skalla-Grím, who died around the year 990, is the protagonist of a thirteenth-century saga detailing his raids with Vikings across much of northern Europe. For all his prowess in battle, the saga tells that Egil was a funny-looking and often sick man. His bones were ‘much bigger than ordinary human bones’, and his skull was ‘an exceptionally large one and its weight was even more remarkable. It was ridged all over like a scallop shell.’ All the better, perhaps, to weather massive blows from the axe of another Viking.

  The saga hero Egil, possibly a victim of volcanic fluorine poisoning.

  Whoever wrote Egil’s saga took care to include these detailed descriptions of his bone deformities. Among other ailments, the warrior suffered from deafness, lethargy, headaches, cold feet and occasional blindness. Some scholars have attributed Egil’s problems to Paget’s disease, in which bones become enlarged and misshapen, particularly around the face. According to this theory, Paget’s disease could account for why Egil described himself as having ‘a helm’s-rock of a head’.

  But Philip Weinstein, a paleopathologist at the University of Western Australia, thinks fluorine could be the explanation. The way Egil is described in the Icelandic sagas is consistent with his suffering from skeletal fluorosis, Weinstein argued in a 2005 paper. Symptoms such cold feet and blindness aren’t easily explained by Paget’s, and whereas people suffering from Paget’s often break their bones, Egil’s bones seem to have been rather robust: more than a century after his death, his skull was reportedly dug up and found to be capable of withstanding a whack from an axe.

  Returning to Laki, we see that Jón Steingrímsson’s chronicle describes symptoms that sound very much like fluorosis. So too does the official report from the Danish-appointed chronicler Magnús Stephensen:

  The same symptoms shewed [sic] themselves, in this disorder, in the human race, as among the cattle. The feet, thighs, hips, arms, throat and head were most dreadfully swelled, especially about the ankles, the knees, and the various joints, which last, as well as the ribs, were contracted. The sinews, too, were drawn up, with painful cramps, so that the wretched sufferers became crooked, and had an appearance the most pitiable. In addition to this, they were oppressed with pains across the breast and loins; their teeth became loose, and were covered with the swollen gums, which at length mortified, and fell off in large pieces of a black or sometimes dark blue colour. Disgusting sores were formed in the palate and throat, and not uncommonly at the extremity of the disease, the tongue rotted entirely out of the mouth. This, dreadful, though, apparently, not very infectious, distemper, prevailed in almost every farm in the vicinity of the fire during the winter and spring.

  In 2004, medical geologist Peter Baxter, of the University of Cambridge, worked with Icelandic colleagues to exhume three bodies buried in cemeteries near Laki. Their goal was to search for signs of fluorine poisoning in the skeletons, such as deformed bones and teeth. Unfortunately, two of the bodies turned out to be at least a half-century too late to have died during the Laki eruption, and the third skeleton showed no evidence of fluorine overdose. For now, the jury is out.

  Tens of thousands – possibly hundreds of thousands – perished across Europe in the aftermath of Laki, and they did not die from fluorine poisoning. Instead, these victims probably succumbed to a combination of factors.

  In 2005, two British volcanologists ventured into historical demography to try to work out how many people Laki may have killed in England. Cambridge scientists Claire Witham and Clive Oppenheimer studied an exhaustive database that included the monthly and annual frequencies of baptisms, burials and marriages in the registers of 404 parishes in 39 counties between 1538 and 1871. The data aren’t perfect: the records cover only a small percentage of the country’s population, are not evenly distributed among the counties, and do not state the cause of death. Still, they are sufficient to reveal out-of-the-ordinary trends.

  Witham and Oppenheimer discovered that the late summer burial rate in 1783 was the highest recorded in the entire eighteenth century. They also found two spikes in death rates: between August and September 1783, mortality was 40 per cent higher than the mean, and between January and February 1784, death rates were 23 per cent higher. Together, these two events accounted for about 20,000 extra deaths across England.

  What could explain these deaths? It’s likely that many were linked to the exhaustion caused by the sweltering heat of the summer of 1783. Insects might also have played a role, in spreading food contamination or disease. Witham and Oppenheimer argue that the warmer temperatures may have bolstered the transmission of diseases that have longer life cycles, such as malaria, which is transmitted by a parasite in female Anopheles mosquitoes and which takes several weeks to progress from mosquito infection to human infection. The sevent
eenth-century English physician Thomas Sydenham described the fevers, or agues, that he associated with the appearance of insects: ‘When insects do swarm extraordinarily and when… agues appear as early as about midsummer, then autumn proves very sickly.’ The time-lag of malaria infection could explain why the summer death toll spiked in August and September 1783 rather than in June and July, when temperatures were hottest. Another possibility is diseases like typhoid and dysentery, which spread more readily during heat waves but take longer to kill. Remember Gilbert White’s observations of swarming flies and spoiling meat; this sort of contamination could have dire consequences.

  Winter brought a whole new suite of health problems. As Laki’s aerosols chilled the continent, people were forced to huddle together for warmth. Diseases such as typhus, which is carried by lice, may have spread more readily. Anyone already weakened by the difficult summer could have then been finished off by the cold and disease of the following winter. This could explain the second mortality spike, in January and February 1784.

  Finally, the dry fog itself may have played a major role in England’s mortality spikes. Bernadette Longo has shown the effects of breathing Hawaiian vog over many months, and the same thing was happening across Europe in 1783. Anywhere the volcanic haze persisted, people were breathing it in – with all the attendant consequences for their health.

  There are plenty of modern examples of how pollution can kill. In October 1948, an atmospheric inversion trapped industrial smog over the small mill town of Donora, Pennsylvania. For five days an acrid haze blanketed the valley. Residents tried to make the best of it, even sending their children out to march as usual in the annual Halloween parade. But within days people were crowding doctors’ surgeries and hospital rooms, complaining of choking and burning in their eyes and throats. The smog had appeared on a Wednesday; the first person died around 2 a.m. the following Saturday. By the time fresh air blew in and cleared out the haze, on Sunday afternoon, twenty people had died. The Donora smog was one of the worst environmental disasters in US history, and served as a trigger for state and federal regulations and eventually the revolutionary Clean Air Act of 1970.