Volcanic Hazards Case Studies PDF

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Volcanic Hazards Case Studies

Soufriere Hills, Montserrat Location Montserrat is an island in the Caribbean Sea, in the Leeward Islands. Its nearest neighbours in the island chain include Guadeloupe to the southeast, Antigua to the north-east and Nevis to the northwest. The island is 16 km long and 11 km wide, with a coastline of about 40 km. It’s other neighbouring countries include Puerto Rico and the Dominican Republic. Eruption The eruption started in July 1997 and prompted an evacuation of 5,000 residence, the capital city of Plymouth was evacuated. The eruption created a Pyroclastic flow which created a mixture of tonnes of hot rock fragments, lava and ash and exploded from the crater in a cloud moving at 100 miles per hour with temperatures reaching over 400 degrees Celsius, it destroyed everything in its way. The eruption lasted over a long period of time and became more active. Effects Over 7,000 people have been displaced from their homes and nearly two-thirds of the island appears to be part of an exclusion zone. The destruction of the capital, airport and much of the land, and continued eruptions, have meant an end to the tourism business in Montserrat. Rock falls caused roadblocks and damages properties, sometimes they are activated by earthquakes. Fine ash is easily breathed by people; causing lung problems and sometimes death. Lots of farms that was in the Exclusion Zone, were destroyed leaving the island without food. It's a huge problem because the island was a self sufficient and most of the fertile lands are in the Exclusion Zone. Some farmers tried to build their crops again at the same place to help the island's crisis. The houses were buried by debris from the pyroclastic flow, burned by the hot pyroclastic surges, or set alight by the intense heat in the atmosphere. Most of the houses destroyed were in the Exclusion Zone. There isn't enough house in the north. Some people, especially the elderly, refused to move to the overcrowded shelters because of lack of privacy, overcrowding and poor sanitation. Management Short-term - the UK government sent help and aid, £10 million given by the international development secretary Claire Short. The British HMS Liverpool had greatly contributed to evacuate the population to other islands; Antigua and Barbuda. 7 000 people (one third of the population) was evacuated; 4 000 to the UK. There were some no entry areas put in place and if people were to go in you would have to register with the police. Long-term - pH of rainwater was used to give an indication of the magmatic gas content.

Nevado del Ruiz, Columbia Location It is a Stratovolcano in west Columbia at the Convergent plate boundary where the Nazca plate is subducted beneath the South American plate. Located within the Andes mountain range, 129 km west of Bogota, the capital city of Columbia. The town of Amero stood at the foot of the volcano in a valley. Eruption There had been nearly a year of minor earthquakes and steam explosions for a year before. The eruption occurred on 13 November 1985 and begun at approximately 3:06pm and caused pyroclastic flows which melted glaciers and snow and generated lahars. Volcanic lakes accelerated the melting of glaciers. At 11:30pm the first wave of water hit Amero, followed by lahars. The lahars caused the most destruction at up to 30 m deep and lasted a total of around 2 hours, flowing down the river valleys of the town. A severe storm occured at the same time as the eruption which may have prevented people from hearing the eruption, so they just stayed inside. The Colombian government didn’t evacuate soon enough, despite prior warnings. Effects The pyroclastic flows melted glaciers forming lahars which were 30m deep, 50m wide and travelled at 12m per second, killing 150,000 animals. However, this did make the land more fertile with the mud from the lahars. In total, 3400 hectares of agricultural land was lost. It cost the Colombian economy $7.7 billion dollars, 20% of GDP from 1985. All roads and communications were destroyed in the areas affected with 50 schools, 2 hospitals, 58 industrial plants and 343 commercial establishments being destroyed. Water supplies were damaged. 23,000 people were killed by lahars and a further 5000 were injured, as well as 8000 being made homeless. In the Armero town, a lahar killed ¾ of the inhabitants. Management Short-term - Colombian Red Cross and Civil Defence personnel were first to organise rescue and medical care. The Colombian military provided helicopters to airlift victims for medical care, distributed supplies and established field hospitals and shelter facilities. Health workers administered over 80,000 doses of tetanus and typhoid vaccines. Long-term - Colombia established a plan for warning and evacuation of areas at risk from another eruption. A public education campaign started in early 1986 to educate people about the dangers of volcanoes. The Red Cross circulated flyers about the volcanic hazard with information about evacuation procedures and warning systems. Hazard maps were distributed in towns and evacuation route markers were painted on buildings.

St Helen’s, USA Location Mount St Helens is located in the north west of USA in Washington and is part of the Cascade Range. It is a typical composite cone volcano as it is formed on a destructive plate margin where the Juan de Fuca plate is subducted underneath the North American plate. Eruption In March of 1980 there were a series of small eruptions of steam and ash from the volcano. By early May there was a visible bulge on the northern flank of the volcano where magma was being pushed to as a result of a volcanic plug that formed in the main vent. At 8:32am on 8 May 1980, the eruption began with the signal of an earthquake with a 5.1 magnitude. This broke the bulge loose, causing the northside to dissolve into a massive avalanche. This release of built up pressure of magmatic gas resulted in a northern lateral explosion. The blast created a 17-18 mile fan shaped path of destruction. The eruption rose 16 miles upward and continued for 9 hours after. Effects 56 people were killed and lahars destroyed over 200 homes, 27 bridges, 185 miles of road and 15 miles of railway, severely disrupting communications in the area. Several logging camps and 250 km squared of forestry were destroyed with 12% of the total crops were damaged or destroyed, especially fruit trees. There was a short term economic loss in Washington of $800 million with the second biggest cost being the clean up operation of $250 million. The Spirit Lake was filled in by the landslide. Out of 32 known species of small mammals only 14 survived, such as the gophers. Over 250 km of river was destroyed by lahars, killing all fish life and over 7,000 big game animals were killed. Flood risks increased on Toutle and Cowlitz rivers. Management Short-term - an exclusion zone was set up and 2000 people were evacuated from the area. The National Guard flew helicopter rescue missions into the blast zone for 2 weeks and rescued 130 people. They also issued clean water, emergency food rations and medical supplies. The Federal Government provided 2 million gas marks to prevent respiratory problems. Ash was cleared from towns like Yakima within 3 days. Long-term - the Toutle, Cowlitz and Columbia rivers were dredged and over 10 million trees were replanted. The bridges were rebuilt with a wider span in an attempt to avoid blockages from future lahars. The volcano is now monitored constantly by the USGs clear plans have been made to prepare and warn people in the area beyond the immediate blast zone to make them aware of the risks of ash clouds.

Mt. Etna, Sicily Location Mount Etna is an active stratovolcano on the east coast of Sicily, Italy, in the Metropolitan City of Catania, between the cities of Messina and Catania. Etna is 10,900 feet (3,329 meters) tall with a base circumference of about 93 miles (150 kilometers). It lies above the convergent plate margin between the African Plate and the Eurasian Plate. Eruption On 27th and 28th October, earthquakes measuring up to 4.3 on the Richter scale occurred and were followed by a series of several smaller eruptions. On 29th October, a large eruption of ash occurred from a fracture on the north east rift. Magma was thrown more than 100m into the air and lava ran quickly down the mountainside, forming 2 separate flows. The ash could be seen from space and fell 600 km south in Libya. Seismic activity on 30th October measured 3-4 on the Richter scale and lava continued to flow in a south eastern direction. Effects More than 100 homes in Santa Venerina were damaged and 1000 people had to leave their homes in Linguaglossa. Schools also had to be shut down there as well as more than 300 family businesses. Catania airport was closed for 4 days as ash was covering the runway and threatened to clog aircraft engines. Ski tourist facilities were covered by flowing lava and these flows engulfed a restaurant and pushed over 3 ski-lift pylons. The tourist station Piano Provenzana and part of Eran Sud were destroyed. Lave caused an explosion at a water tank which injured 30 people. Orange and vineyards were ruined in Zafferana. Management Short-term - the Italian government provided £5.6 million in aid and a ship with an emergency clinic was positioned off Catania in case of emergencies. The residential areas in Linguaglossa were evacuated due to lava flow threats and villagers paraded their patron saint through the village to ward it off. Rescue workers tried to divert lava that threatened to engulf a volcanic monitoring station at the base of Mt Etna. Emergency workers dug channels to divert the northern flow away from Linguaglossa. Long-term - Italian governments gave tax breaks to 300 families who were affected by the eruption. Tourist facilities and damaged buildings were rebuilt. The volcano is being constantly monitored scientists, who have improved their monitoring techniques. As the area has frequent eruptions the locals have been educated on what to do in a similar situation as well as putting evacuation plans in place.

Eyjafjallajökull, Iceland Location It is a subglacial volcano found in the south of Iceland lying within the country’s East Volcanic Zone, southern end of the volcano was once part of the Atlantic coastline. Iceland lies on the Mid Atlantic Ridge, a constructive plate margin separating the North American plate and the Eurasian plate. A large magma chamber under the mountain feeds Eyjafjallajokull. The chamber derives magma from the tectonic divergence of the Mid-Atlantic ridge. Eruption The eruption in 2010 began in January with the onset of small earthquakes and by early March the earthquake activity had increased in intensity and frequency. On 20th March, it began spewing molten lava in south Iceland and on 14th April the volcano resumed erupting from the top crater in the center of the glacier. The renewed eruption caused massive flooding. The second eruption threw volcanic ash several kilometers up in the atmosphere and ash plumes could be seen from miles away. The disruption lasted for six days, from 15th till 21st and on 23rd May the eruption was declared to have stopped. Effects The 150m thick ice cap melted which caused major flooding to Iceland and 700 people had to be evacuated. The eruption destroyed parts of the main Route 1 road and other roads were bulldozed to allow flash flood water to reach the sea. Fine ash silted the rivers caused blockages even a year later. Around 20 farms were destroyed by both the ash and flooding. The fine ash posed an issue to airlines and airspace closed across Europe with 17,000 flights a day being cancelled. There were 6 flightless day and a total of 95,000 cancelled flights. This cost airlines $200 million a day and an estimated $2 billion overall. Less fuel was needed so 1.87 million barrels were not in demand causing a loss in the oil industry. It was estimated that London lost £102 million of tourist income, causing a knock on effect for travel workers and businesses. Management Short-term - rescue teams and people living near Eyjafjallajokull used last minute defences as they cut away the roads before it got washed away by the floods. Both police and rescue teams aided local people in evacuating their homes. Long-term - the ash from the eruption was dug up from the bottom of rivers in order to make them deeper. High tech equipment was installed and currently used to measure volcanic activity. Existing warning systems were developed and a text message system was added to warn people within 30 minutes of the volcanic eruption if there were to be one.

Nyiragongo, Congo

Location Nyiragongo is a steep-sided, active volcano. It is located in the Democratic Republic of Congo. Nyiragongo and the shield volcano of Nyamuragira, 40 km away, are part of the East African Rift Valley. This is an area of many faults where the plates are being stretched as they move away from each other. Eruption The eruption happened on 17 January 2002. The volcano has a lava lake in its crater. Fissures opened up to the south side of the volcano and three streams of lava from the lake drained through the fissures. The lava reached speeds of 60 km/h. There was very little warning as the lava reached the city of Goma. The unrest in the country made it difficult to monitor the volcano and put emergency responses in place. Effects Around 12,500 homes were destroyed by ash and lava and 14 nearby villages were destroyed. Many people had to move to overcrowded refugee camps as 400,000 people were evacuated. 45 people died in the first 24 hours and around 50 people were killed when fuel exploded while they were trying to siphon it off at a petrol station. The lava flow made it difficult to travel around Goma as it filled the roads and took a long time to cool and it burnt people as they tried to return to their homes. Cholera spread because of lack of sanitation in areas that people fled to. Lava covered 15% of Goma and destroyed 30% of the city. Aviation fuel stores exploded as the lava flow damaged Goma airport. Poisonous gases caused acid rain, which affected farmland and cattle as many lost income. Management Short-term - aid agencies provided bedding, water, food, shelter and clothing to those in need after the destruction of the eruption. The UN supplied 260 tonnes of food which was enough for 700,000 people for a week. Around 220,000 people fled to Rwanda. Long-term - there was the cleaning up of lava and ash from streets. Volcanology was taught in schools in order to educate the local community further. There was more investment put into research and prediction for future volcanic eruptions.

Merapi, Indonesia Location The volcano and its eruptions were caused by the Indo-Australian Plate being subducted beneath the Eurasian Plate. The volcano is located on a destructive plate margin, at a subduction zone, part of the Pacific Ring of Fire. Eruption In March 2010 there were the first signs that the volcano would erupt. Tiltmeters showed that the volcanic dome had begun to bulge. In September there was increased earthquake activity and white plumes of smoke were seen rising above the volcano's crater. On Monday 25th October 2010, Merapi erupted and continued to erupt until 30th November. Volcanic bombs and heat clouds, with temperatures up to 800°C, spread over a distance of 10 km and pyroclastic flows travelled 3 km down the heavily populated mountain. Volcanic ash fell 30 km away and travelled 6 km into the sky. Villages, such as Bronggang, were buried under 30 cm of ash. Sulphur dioxide was blown across Indonesia, the Indian Ocean and as far south as Australia. Effects 353 people were killed and 577 people were injured. Ash clouds caused major disruption to planes across the region. Roads were blocked with as residents tried to flee the hazard zone (350,00 people had to flee their homes. Vegetable prices increased because of the damage to crops. Heavy rain on 4th November caused lahars, washing ash and rock down into towns and destroying bridges. Overcrowded evacuation centres led to poor sanitation and a serious risk of disease. People, particularly farmers, lost their homes and livelihoods. A positive is that the ash cloud from Mount Merapi eruption Ash will eventually lead to more fertile soils in the area. Management Short-term - 210 evacuation centres were set up in schools, churches, stadiums and government offices. An exclusion zone of 20 km was established around the volcano. Indonesian Disaster Management Agency organised volunteers, the military and police to circulate information, rescue survivors, control traffic, set up hospitals and kitchens in evacuation centres. International aid was offered from governments and non-governmental organisations (NGOs) such as the Red Cross and Red Crescent. Long-term - 2,682 people were moved to new, safer houses permanently. The government aided farmers to help replace their livestock and set up a special task force to support people who were affected by the volcano, either by family issues, or because they lost their jobs. An ongoing exclusion zone of 2.5 km was set up and improved prediction measures and education in evacuation procedures have been introduced. Dams have been built in valleys to hold back lahars

Pinatubo, Philippines Location Mount Pinatubo is an active stratovolcano in the Zambales mountains on the island of Luzon in the Philippines, part of the Pacific ‘Ring of Fire’. It is one of a chain of volcanoes known as the Luzon volcanic arc, which is the result of the Oceanic Philippine plate being subducted under the lighter Continental Eurasian plate, making it a destructive plate boundary. Eruption Pinatubo violently erupted in 1991, being the second largest eruption in the 20th century. Large numbers of people live in the vicinity, 500,000 within 40 km, making it deadly. Early warnings and evacuations saved at least 5,000 people during the eruption. The eruption was so violent, gas, ash and steam was hurled into the air and classified level 6 on the VEI scale. Effects An ash cloud covered 125,000 km squared, bringing darkness to central Luzon as well as volcanic ash smothering 80,000 hectares of land. This also destroyed 150 km squared of reforestation projects. The global cooling caused by the ash dropped temperatures by 0.5 degrees celsius. Acid rain was produced due to 22 million tonnes of SO2 erupting. 800 km squared of agricultural land was destroyed and 800,000 livestock was killed, costing 1.5 billion pesos. 847 people were killed by collapsing roofs, 100 killed by lahars and 500 died from diseases like measles in refugee camps. Ash and pumice destroyed 42,000 homes, causing 1.2 million to become homeless. Many indigenous Aeta people had to move into government organised resettlement areas which caused the society to become fragmented. Management Short-term - Manila airport was forced to close. 200,000 people had to be relocated elsewhere. The Red Cross, Action Aid and Oxfam provided food and blankets in evacuation camps. 23 USGS personnel helped to advise the community and government officials for 8 weeks. Long-term - President Ramos created Mount Pinatubo Commission in order to raise 10 billion Filipino pesos in aid. New houses had to be built on stilts so that future lahars will not bury them. Both Norway and the UK governments sent millions in the form of aid. Overseas Filipino workers provided clothing for victims of the volcanic eruption. Around 5 billion pesos was spent to build dykes for lahars (later washed away by the lahars). There were also lahar detectors put in place as well as the addition of hazard maps. The volcano continued to be monitored by scientists....