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Home , Anak Krakatoa, Lake Toba, Limnic eruption, Mount Tambora, Ojos del Salado, Volcanic crater

Natural 4Volcano Volcanoes are vents or pipe-like fissures bringing molten rock, or , rushing to the surface from under the ’s crust. But, it is not direct contact with fiery that costs the most lives.

Introduction How Earth’s violent A case study … he weather forecast was Iceland’s Eyjafjallajokull eruptions unleash good and the crew of a British recorded a moderate eruption, but TAirways Boeing 747 expected its ash cloud grounded flights across many dangers a calm flight to Perth from Kuala Europe and the United Kingdom for Lumpur, , on the night of weeks. This led to economic loss June 24, 1982. Soon after takeoff, of more than $4 billion to global icture a steep volcano in the Democratic Republic of Congo, as the jumbo passed over at a economic productivity, showing in Africa. Sitting in its summit is a roiling, hissing of cruising altitude of 37,000 feet, puffs how a modern, networked world is Plava, one of the largest in the world. White gases spout from of “smoke” billowed from vents in vulnerable to even relatively small the crater by day and at night its red glow lights up the sky. The the cabin and strange, -like light volcanic eruptions. volcano, called Nyriagongo, is not far from , the beauty clung to the windscreen and wings. Eyjafjallajokull started smoking of which masks a deadly secret. Massive amounts of and One by one, all four jet engines ash and gas in March, 2010, and are dissolved in the waters and held under glowed, “flamed out” and shut down. continued throughout April. When The captain, who had no idea what meteorological conditions drove beneath the surface. A disturbance such as a volcanic eruption or an was causing this freaky occurrence, the cloud over central Europe, the could release these gases in a toxic cloud. This is called put the plane into a steep glide. The Advisory centre in a limnic eruption, or “lake overturn”. engines finally re-started and the London told air safety authorities, Between the vast lake and the restless mountain is a city, , crew made an emergency landing who closed airspace. Passengers home to at least 1 million people. Many among its fast-growing in . The invisible culprit? were stranded for days at airports in population have fled wars and violence in this politically unstable It was volcanic ash from Mount London, Munich, Paris and Frankfurt. region. It is also geologically unstable, part of the Great African Rift Galunggung, in . Analysts say we can expect system where the underlying tectonic plate is pulling apart. There Volcanic ash clouds, which are similar events about every 50 not detected by radar, are a serious years, with smoke and ash from are many volcanoes. hazard to aircraft. More than 80 an Icelandic volcano causing air Like any natural , several factors working together lead commercial aircraft traffic chaos. The Laki to catastrophe. Could this combination – constant seismic activity, have unexpectedly eruption in Iceland in a dangerous lake, an unpredictable mountain and vulnerable encountered ash in the 1783 was about 100 humans living close by – become the world’s next volcanic disaster? air or at airports in the times stronger. We can Nyriagongo sent lava flowing into Goma in 1977 and again in past 15 years. Seven had expect these mega-eruptions 2002, but scientists believe it is capable of causing much greater loss of engine power in flight, somewhere in the world every devastation. Some scientists are worried that the town could nearly causing crashes. In 2010, 250 to 300 years. become a modern . (In AD79, poisonous fumes and hot volcanic ash exploded from Italy’s , burying Pompeii and Herculaneum. Some 3500 people are thought to have died. Vesuvius is still active and although it is watched 24 hours a day, it remains a threat, including to nearby Naples.) Eruptions can endanger lives in many ways: ash falls, pyroclastic flows, mud flows, lava flows, and , or starvation from crop failures and deaths of animals. Hundreds of thousands of people have died or been seriously affected by volcanic activity. When , in Indonesia, blew its top in 1815, at least 92,000 people lost their lives. The ash cloud was so big it brought about a fall in global , by 3 degrees. Today, volcanoes are closely monitored and people can be evacuated from harm’s way. However, the signs don’t always predict exactly when and how a mountain will erupt. In some regions, like the Asia Pacific, populations are growing so fast that moving millions of people would be extremely difficult. Geoscience Australia estimates that 180 million people in the Asia-Pacific region live within 50 kilometres of a dangerous volcano. What causes dangerous volcanoes and where do they occur? How can a volcano sit quietly for hundreds of years and then suddenly burst into life? How do big affect the world’s ? Can you tell when they are about to blow? Read on for Keeping an ear to the ground answers to some of these questions.

an you predict volcanic eruptions? Yes, but not perfectly. and seismologists use various techniques to Cmonitor volcanoes and read their signs, especially of those near Some of the worst where people are living. Understanding the unique geology of each volcano – its rock chemistry and its “plumbing” – is also important, as well as its Laki, Iceland characteristics in past eruptions. An eruption Steam releases, earthquakes and tremors, ground deformation such as 178 3 ripped open a bulging or cracking and changes in volcanic gases emitted may be signs huge fissure over a volcanic field that an eruption is imminent. Quakes always come before eruptions and are with dozens of boiling craters. a sign that molten magma is rising from a deep chamber through fissures For eight months, toxic gases or vents. Other instruments measure how the lava is moving underground. belched into the atmosphere. Lava Changes in ground levels, such as swelling, even by millimetres, show that covered 600 square kilometres. the pressure is varying inside. Gas “sniffing” instruments look for increases People, crops and livestock in carbon dioxide and sulphur dioxide, signals that magma is pushing to the suffered from acidic fallout. With surface. Cameras, satellite imagery and aircraft observations are used too. the volcanic cloud blocking the Countries with volcanoes have their own volcano observatories. Some are sun, the European summer was members of the World Organisation of Volcano Observatories. Organisations effectively wiped out, and weather such as the Smithsonian Institution’s Global Program keep a close changes affected the entire eye on all historically active volcanoes. Scientists can tell that an eruption is . Laki pumped likely, but it is difficult to pinpoint its exact time or nature. Observatories make 122 million tonnes of sulphur forecasts with great care, because moving large numbers of people from dioxide into the atmosphere, Although relatively small for volcanic eruptions, the events at Eyjafjallajokull in 2010 caused much disruption to air travel across western and northern their homes, often from farms with livestock, has huge implications. In 1991, sulphuric acid droplets formed and Eyjafjallajokull … scientists were able for forecast the massive eruption of , in these damaged plants. Fish deaths The area today. Europe. Seismic activity started at the end of 2009 and gradually increased in intensity. From April 14-20 that year, many countries then closed their airspace. Consequently, a high proportion of the . The government moved 50,000 people out of a 16-kilometre from acid were reported in Scotland. A different gas, hydrogen fluoride, gave flights were cancelled, creating the highest level of air disruption since World War II with hundreds of thousands of travellers affected. More disruption continued in May 2010, when this photo was zone around Pinatubo. The was devastating, but the warning kept people and livestock fluorosis, which deforms the bones. Fluorosis and taken. The eruption was declared over in October 2010 although the area is still active and could erupt again. Photo: natgeotv.com.au the immediate death toll to about 500. killed many thousands of people. Also, Laki is said to have contributed to the French Revolution of 1789 by causing crop destruction and poverty in France. Mount Deadliest and costliest volcanic eruptions 1000-2010 The arsenal of hazards Fact file Tambora, The making The map shows the location of volcanoes worldwide, as well as the costliest and deadliest eruptions since AD1000. 1815 Indonesia n About 500 volcanoes are active kilometres of lava and so much Four eruptions – in 1258, 1600, 1783-84 and 1815 – had a significant worldwide impact on climate. As the site of the deadliest eruption of a volcano Lava flows. Lava is very hot liquid today, with 15 to 20 erupting now. and ash into the in recorded history, this volcano rock, or magma, which flows from This does not include those under stratosphere that it masked heat from killed 92,000 people directly or volcano is a vent, or vents or cracks in the Earth’s surface. the sea. the sun, affecting the world’s climate. by starvation and disease. This a series of vents and It comes from kilometres below. Gas n The tallest active volcano is massive on Acracks, through the in the magma causes it to rise and Nevados Ojos del Salado, on , east of Java, sometimes Earth’s solid crust, connected collect in chambers under the volcano. the -Argentine border, at called the “Pompeii of Indonesia”, to a chamber of molten magma Pressure builds and forces gas and 6887 metres. It has fumaroles near may have been dormant for 5000 below. The magma has risen magma up through volcanic vents and the top. It is open to hikers. years. But months, and possibly from the red-hot liquid mantle fissures. Lava flows destroy everything n Kilauea, the youngest volcano on years, of increased steaming and tens of kilometres beneath the they touch, but most move slowly the Big Island of Hawaii, is probably small eruptions occurred before surface. Dissolved gases in enough for people to get out of the the world’s most active volcano, An artist’s impression. the mountain exploded in April. It magma, including water and way. Varying types of lava come from producing lava since 1983. Tourists erupted at least 50 cubic kilometres of magma. Pyroclastic flows reached the carbon dioxide, form bubbles different volcanoes. Deaths from lava flows are often indirect and caused by visit to watch the spectacle. sea on all sides. Its was estimated to be 40 kilometres high, and expand as the magma onlookers getting too close, breathing toxic gases, through fires or through sending so much volcanic ash and gas into the atmosphere that it lowered the moves upwards and the explosions when lava hits water. world’s temperatures by 3 degrees. More than 30 cubic kilometres at the top pressure decreases, giving the Summit of Nyriagongo. of the mountain collapsed. Floating of 5 kilometres long were volcano its expelling force. Pyroclastic flows and surges. seen at sea. Most volcanoes occur near These are the most dangerous. n Low silicate content makes lava the boundaries of the tectonic Dense, super-hot clouds of gas and from Nyriagongo, in the Democratic , plates of the Earth’s outermost pulverised rock rush away from the Republic of Congo, some of the Indonesia shell, the lithosphere. These vent at speeds of between 70km/h and fastest-flowing in the world, reaching 18 8 3 This is better plates move over the mantle, 200km/h. Most have a base flow of speeds of up to 70km/h. known than the Mount Tambora bumping into each other, coarse fragments that hurtle down the volcano because by this time, the and pushing over each other, mountain and along the ground, and a overland telegraph had been built creating tremendous . turbulent cloud of hot volcanic material and the world heard the news. The Where plates converge, a thinner above. Ash often falls from this cloud Lava on the island of Hawaii. massive eruption in August killed plate is thrust down under a over a wide area downwind. The flows 36,000 people. The explosion was thicker plate (). When contain rocks from boulder to ash size, all very hot, so they bury, burn or carry n Volcanic activity is hot. Lava in 13,000 times more powerful than it reaches about 100 kilometres away everything in their path, including forests and farmland. Deaths may be Kilauea reaches 1160 degrees; Hiroshima. Two thirds of the island into the mantle, it starts to melt, caused through inhaling hot toxic gases. pyroclastic flows reach more than of Krakatoa was blasted away, forming new magma. Some of 800 degrees and travel at 200km/h. followed by huge tsunamis that this rises and erupts as lava . These are wet mixtures of n Nearly 200 hectares of new land were triggered by the mountain from volcanoes. Eruptions can water and rock, like a coarse slurry, has been added to Hawaii’s Big collapsing into the sea. More than be explosive or quiet. flowing down a volcano or a valley. Island by Kilauea since 1994. Lava 160 villages were swept away. The Other volcanoes are formed l Deadliest volcanic eruptions Volcanic eruptions since They can be hot or cold and the rock Airport flight chaos. has also covered large parts of the sound of the eruption was heard as tectonic plates pull apart, since AD1000. AD1000 with significant can be of any size, from pebbles to island and destroyed180 buildings. in Perth. Global temperatures fracturing and stressing the l Costliest volcanic eruptions worldwide effects on climate: boulders. Lahars often form when n Volcanic ash cannot be detected n Australia has extinct and dormant dropped due to atmospheric gas crust and letting magma pour since 1980. 1. Location unknown pycroclastic flows melt snow and by radar and is a grave danger to volcanoes. One chain, created by a and ash. Krakatoa sits directly out through cracks and vents. Costliest and deadliest volcanic (possibly El Chichon, ) ice, when water is ejected from a aircraft engines (see A case study hotspot under Bass Strait, has its over the subduction zone of the This is happening in the African eruptions. 1258. crater lake or heavy mixes with above). Nine ash advisory centres oldest volcanoes in Queensland and Australian and Eurasian tectonic plates, where magma is forced upwards. A Rift system. Others, such l Volcanic eruptions since 1980 2. , 1600. loose volcanic rock and ash. Many around the world, including one in its youngest in Victoria. new active volcano, , has emerged from the sea and is growing as volcanoes that made the that have caused losses and/or 3. Laki volcano, 1783-84. begin as on the sides of Darwin, track ash clouds and warn n Mount Macedon was once a by an average of six metres a year. If a similar eruption happened now, a Hawaiian Islands and also the deaths. 4. Mount Tambora, 1815. volcanoes and gather water and debris aircraft. volcano. million people could be killed. ancient volcanoes in Australia, ▲ Volcanoes Source: Munich RE, Topics Geo 2010 from scoured rivers and valleys as n The deadliest recorded volcanic n The southern-most historically are a long way from plate they progress. Lahars can move much too fast to outrun. In 1985, lahars eruption was Mount Tambora, in active volcano is Mount Erebus, Mount boundaries. They were formed in flowed off the volcano, triggered by the Indonesia, in 1815. About 92,000 1387 kilometres from the South Lamington, by very hot, stationary plumes sudden melting of ice at the summit. Within four hours, they had travelled people died from the explosion and Pole, on Ross Island, in . 19 51 New Guinea of magma called hotspots. 100 kilometres. The flows killed more than 23,000 people, injured more than hot ash fall, starvation and disease. This volcano still has a molten lava This lush, -covered Volcanoes slowly form as the They come in different shapes and sizes 5000 and destroyed 5000 homes. n Mount Tambora ejected 100 cubic lake. mountain was not even recognised upwelling breaks through as a volcano until it erupted tectonic plates moving over it. Stratovolcanoes. Also called including Kilauea and Mauna Loa, congealed lava coming from a Ash clouds. Explosive volcanoes can violently, sending devastating Chains of volcanoes, which are composite volcanoes. They often in Hawaii. Mauna Loa, the world’s single vent. The gas-filled lava is eject ash and gases many kilometres pyroclastic flows down the slopes. progressively younger as they look like steep, cone-shaped largest , stands ejected into the air, breaking into into the atmosphere, where they are Some reached 12 kilometres away move away from a hotspot, form mountains. They are made from more than 8500 metres above the fragments that cool and fall as spread by high-altitude . Lower from the mountain. An in this way. stratified layers of lava as well sea floor. cinders. One of the seven natural ash clouds deposit heavily in the ripped the side of the mountain Most volcanoes are under the as ash, blocks, cinders and wonders of the world, Paricutin regions around the volcano, collapsing apart, and a roar was heard sea, where the ocean floor pulls other volcanic fragments. They . These are formed in Mexico, is a cinder cone buildings, polluting water supplies, 320 kilometres away. More than apart and magma rises to form erupt from the summit where when massive volcanic explosions, volcano. A farmer witnessed its cutting power and killing crops and 3500 people in 29 villages died. new crust. These regions are most have a crater supplied with such as the one at Krakatoa, birth when a fissure opened in his animals. It was falling ash – tiny, called spreading ocean ridges. magma from a central vent or Indonesia, in 1883, blow out tens cornfield. abrasive pieces of rock and glass – that More than half the world’s cluster of vents. They can also to hundreds of cubic kilometres crushed and buried Pompeii. So much volcanoes are around the erupt from fissures on the flanks. of magma. When so much Submarine volcanoes, ridges volcanic ash and gas was ejected from Summit of Nevados Ojos del Salado. Summit of Mount Erebus. Nevado del Pacific , which has Mount Fuji, in Japan, , in material is removed from under and vents. Most volcanoes are Mount Tambora, Indonesia, in 1815 that Ruiz, ColOmbia plate boundaries circling the Ecuador, and Nyriagongo, in the a volcano, the ground collapses unseen under the oceans. New it lowered the world’s temperatures by shielding heat from the sun. Volcanic 19 8 5 When this Pacific basin. The ring passes Democratic Republic of Congo, to form a depression called a ones are frequently discovered by ash can stall jet engines and it cannot be detected by aircraft radar. Aircraft stratavolcano spat out 20 million , Tonga, Papua are stratovolcanoes. . Some of the biggest multi-beam sonar and research instruments, lights, windows, wings and air supply can also be damaged. In cubic metres of hot ash and rocks, New Guinea, Indonesia, the are 85 to 90 kilometres long and submarines. Some blast steam 2010, ash from Iceland’s Eyjafjallajokull volcano rose 10 kilometres and blew Learn more at: it melted ice that capped the Philippines, Japan, Alaska Shield volcanoes. These several kilometres deep. They are and rock high above the sea. around Europe and the Atlantic. The ash cloud stopped air travel for weeks. n ga.gov.au/hazards/volcano.html summit, releasing water. Lahars, and the Americas. Most of the are flatter and wider than some of the most active volcanic Others lie at great depths n volcanoes.usgs.gov/hazards/index.php wet flows full of debris and gases, infamous volcanoes such as stratovolcanoes and built almost features, having earthquakes, and even large eruptions may Earthquakes and tsunamis. Volcanoes and earthquakes often occur n volcanodiscovery.com/nyiragongo.html poured down the slopes. It was Mount St Helens, in the US, entirely from fluid, basaltic lava. ground cracks, geysers and not disturb the surface. Vents in the same regions because of tectonic plate movements. Volcanoes n nps.gov/havo/index.htm night. The flows joined, scouring Krakatoa, in Indonesia, and Flows pour in all directions from boiling mud pots. The three largest discharge mineral-rich water at can trigger quakes when molten magma is injected into rock cracks and material along the way until in Cotopaxi, in Ecuador, are here. central summit vents or fissures calderas in the world very high temperatures. Some cavities far beneath the surface. This causes changes in stresses in rocks places they were 40 metres thick. in the sides. These flows build up are Yellowstone National Park in support new kinds of marine life. underground. Tsunamis are caused in a number of ways, including through At Armero, 48 kilometres from the a broad, flattened dome, looking the US, in Indonesia Last July, scientists using ship- explosive force, landslides or pyroclastic flows hitting water, and through Produced on behalf of The Age by volcano, the flows swept away a bit like a warrior’s shield. They and in New Zealand. borne, sea-mapping technology collapsing calderas (a large volcanic crater) and undersea eruptions. Clemson Text & Design. or killed three quarters of the are not as explosive, but the fluid found 12 new volcanoes near the Hawaii has suffered extensive damage from volcano-generated tsunamis, Research and writing by population. Some 23,000 people lava spreads over great distances. Cinder cones. These are the South Sandwich Islands, some as has Alaska. The 1883 explosion of Krakatoa, Indonesia, triggered giant Published by The Age Company Pty Ltd Leith Young. died in the region and 5000 were Some of the largest volcanoes in simplest types of volcano, built three kilometres high. Seven were tsunamis that washed away 165 villages on Java and , killing more ABN 85 004 262 702 of 655 Collins Street, Design by Docklands 3008. Andrew Wolf. injured. It was the second worst the world are shield volcanoes, from particles and blobs of active and others had collapsed. than 36,000 people. Tsunamis were recorded 7000 kilometres away on the Series edited by Ben Haywood, manager, www.davidclemson.co volcanic disaster of the 20th century. Arabian peninsula. Education Resource Centre