2. Stress built up as the plates moved past each other (1). The stress/energy was released causing the plates to move suddenly (1).

Transcription

1 Natural disasters Teachers notes This work could be completed individually, in pairs, or small groups. Answers to questions 1. Radioactive processes release heat (1) which causes convection currents in the mantle (1). 2. Stress built up as the plates moved past each other (1). The stress/energy was released causing the plates to move suddenly (1). 3. No. Earthquakes are difficult to predict because: It is impossible to know when the stress will build up to the point that it is suddenly released (1). It is impossible to know where on the fault line the stress will be suddenly released (1). We cannot see below the Earth s crust (1). 4. Any 3 of the following: The epicentre of the earthquake was very close to the capital city/a highly populated area (1). The epicentre of the earthquake was not far below the Earth s surface (1). The buildings had not been built to withstand earthquakes (1). Transport links to Port-au-Prince were damaged by the earthquake (1). Hospitals ran out of staff and equipment (1). 5. Magma underneath the volcano got to the surface (1). Pressure from gases built up below the surface and was released suddenly (1). 6. Any 2 of the following: Historical record of eruptions (1), seismic waves (1), observable activity (1). 7. Any 3 of the following: Large ash cloud produced (1)which meant flights across Europe had to be grounded (1). People stranded (1). Airlines lost money (1). 8. History shows that Katla has erupted every time Eyjafjallajokull has erupted (1). The volcanoes are close together and experience the same tectonic forces (1). Katla is a larger volcano so could cause more problems (1). 9. Iceland is on a fault line/boundary between plates and the UK is not. (1 mark) Page 1 of 5

2 Natural disasters 1. Look through the questions at the end then read the articles, highlighting the key points as you go and using the questions for guidance. 2. Use your knowledge and the information you have gathered to answer the questions. Haiti earthquake January 2010 Hundreds of thousands still missing after earthquake strikes Haiti A 7.0 magnitude quake hit Haiti yesterday in the worst earthquake the country has experienced in over 200 years. The quake struck at (local time) as children played in the busy streets of Port- country in the western hemisphere. au-prince, the capital of the poorest As the earth shook, homes, offices, government buildings and the local UN headquarters were destroyed, killing and injuring scores of people. Survivors could only watch in horror as cheaply built homes that were not designed to withstand earthquakes collapsed on their screaming occupants. It is difficult to predict the death toll at this stage, but it is already clear that this earthquake, whose epicentre was just 5 miles below the surface and only 10 miles from Port-au-Prince, will cause huge suffering in a nation that is ill-equipped for such disasters. Haiti lies on a strike-slip fault line where the Caribbean and North America plates are grinding past each other at a rate of about 2 cm per year. As the plates move past each other, stress builds up until it is suddenly released. Experts say that stress has been building up along the fault line for a long time, and that an earthquake was inevitable at some point. At the moment it is uncertain whether there will be aftershocks as stress is moved to locations further along the fault line by the earthquake. The Caribbean and North America plate have been moving past each other at a rate of about 2cm per year. As the plates catch on each other stress builds up until it is suddenly released and the plates suddenly move, causing an earthquake. What do you think... Page 2 of 5

3 ...about how the Haiti earthquake was dealt with? In our regular column this week, we interviewed shoppers in Kingston upon Thames, asking them particularly about how well they thought the agencies responded to the disaster and whether there were any lessons that we could learn for the future. Opinion was divided about whether more could have been done in the immediate aftermath of the earthquake. Many people said that aid should have been brought in quicker, but others recognised that the damage to the airport, roads and port hampered the relief efforts. One member of the public raised an interesting point however: This is the age of science. We can build tiny devices that can store huge amounts of information and can collide tiny particles together to find out about the beginning of the universe! Surely we can predict earthquakes. We can predict hurricanes after all! I think our scientists need to step up and tackle some of the issues that people care about rather than wasting their time elsewhere. Thousands of people died in this earthquake! We interviewed Stephen Martin, a geophysicist and expert on earthquakes to get his response to the criticism. Is this a fair point? Are there enough scientists working on earthquake prediction? Well, I think it would be great if there were more scientists working on earthquakes like me, but I m not sure that having more people would make much difference to our progress. Predicting earthquakes is just not as simple as people think. There are so many unknowns and difficulties. The problem isn t really to do with manpower. What are the difficulties? At a basic level, the problem is that we can t see what is happening below the Earth s crust. It is convection currents in the mantle, driven by heat released by radioactive processes, that cause the tectonic plates to move, but we obviously can t see these convection currents. The plates are actually moving constantly, but only very slowly. Earthquakes are caused at plate boundaries. Haiti lies on a fault line, where two plates are sliding past each other. Stress built up over a period of time, until it was too much and the plates moved suddenly, causing the earthquake. So surely you could predict areas where earthquakes are likely to happen? To an extent, yes we know where the fault lines are and these areas are obviously more likely to experience an earthquake. The problem is that even though we know that stress is building up between plates, it is impossible to know where along the fault line the stress will be released. Could the people in Port-au- Prince have been evacuated? No. We knew that there might be an earthquake at some point along the fault line, but couldn t predict exactly where. For all we know, evacuating people from a certain area could bring them closer to danger. The other problem is that even if we knew where an earthquake was going to happen, we couldn t predict when the stress would be released. It s not just practical to evacuate people for a long period of time scientists are often wrong by decades on their earthquake predictions! Facts and figures The earthquake, which reached 7.0 on the Richter scale, caused more damage than similar magnitude quakes in other parts of the world. Haiti is the poorest country in the western hemisphere and the quake was the worst to strike Haiti in 200 years. The quake caused 230,000 deaths, 300,000 injuries and left 1.2million people homeless. Hospitals were destroyed. Those left were overcrowded, short of staff and ran out of essential drugs and equipment. Thousands of families were separated in the chaos. In the first week 22,000 people registered for help finding loved ones. The earthquake destroyed government buildings, power and telephone lines, damaged the port and airport, and blocked roads, hampering relief projects. Page 3 of 5

4 EYJAFJALLAJOKULL ERUPTION APRIL 2010 Iceland volcano causes biggest shutdown of European airspace since World War II The huge ash cloud that has engulfed European airspace has grounded an estimated 10 million travellers and cost the airline industry 2.1 billion pounds. Thousands of British holiday makers were stranded abroad during the flight ban, many struggling home by train, bus and boat in journeys that lasted several days in some cases. The ash originated from Eyjafjallajokull, an Icelandic volcano with a history of long eruptions. Its last eruption, which started in 1821, stopped and started several times before eventually ending in Whilst the flight ban chaos seems to have eased for now, history warns that there could yet be more to follow, and many people are already thinking of staying in the UK over the summer in order to avoid air travel. Perhaps more seriously, scientists are warning that this eruption might trigger the more violent eruption of Katla, Eyjafjallajokull s nearby and much larger sister volcano. We don t know what the link is, an expert told us, but the two volcanoes are being subjected to the same tectonic forces. It s very possible that if the magma can find a way to the surface from underneath one of the volcanoes, it might also rise to the surface beneath the other. History again supports this possibility. Every eruption from Eyjafjallajokull has been followed shortly afterwards by an eruption from Katla, although our expert was keen to remind us that the historical record is too short to draw any firm conclusion from. She also told us that, whilst seismic waves are carefully monitored, they are not always useful in predicting an eruption. Watching closely and waiting for signs of activity is still the best option she said. Iceland is home to several active volcanoes and the visible volcanic activity on the island draws in thousands of tourists each year. The reason for this activity is Iceland s location straddling the Mid-Atlantic Ridge, the fault line between the North American and Eurasian plates which are moving apart from each other at the rate of a few centimetres each year. As molten rock from the mantle moves up to the surface of the Earth it forms a volcano. Pressure rises as dissolved gases from the magma build up, until the pressure is too great and is released in an eruption. These eruptions can cause huge destruction to surrounding areas, as well as releasing ash and sulphur dioxide which pollutes the atmosphere and causes acid rain. The cause of Eyjafjallajokull s eruption Page 4 of 5

5 Natural disasters Questions 1. The Earth s lithosphere is broken up into tectonic plates. Describe the processes that cause the plates to move. 2. Why did the Haiti earthquake happen? 3. Do you agree with the member of the public who said Surely we can predict earthquakes. We can predict hurricanes after all! Explain your answer. 4. Why did the earthquake in Haiti cause so much suffering compared to many other earthquakes around the world? 5. Why did Eyjafjallajokull erupt? 6. What kind of evidence do scientists use to predict and monitor volcanoes? 7. Eyjafjallajokull s eruption was not particularly violent compared to many other volcanic eruptions. Describe and explain how the eruption had such a major effect on the world and especially Europe. 8. Why did scientists think that Eyjafjallajokull s eruption might trigger the eruption of Katla? Why were they worried about this? 9. Why are there several active volcanoes in Iceland but none in the UK? (1 mark) Page 5 of 5