Intro Quiz: How can we predict, protect and prepare for volcanic eruptions?

Video: How can we predict, protect and prepare for volcanic eruptions?

﻿Hi, my name is Miss Earthrowl, and welcome to lesson six in the key stage three, unit of work on plate tectonics. Today, we're going to be looking at how you can predict, protect, and prepare for volcanic eruptions. For today's lesson, you will need a pen and a pencil. You'll also need a piece of paper or an exercise book to write in. If you can find yourself a quiet space away from any distractions, then that will really help with your learning. So get yourself ready, find that quiet space and press play once you're all set to go. Welcome back. So the key question for today's lesson is how can we predict, protect and prepare for volcanic eruptions? Now, a volcanic eruption is a natural hazard. A natural hazard is a natural event, such as an earthquake or a volcanic eruption, that threatens people, or has the potential to cause damage, destruction and death. Over 500 million people are thought to be living on, or near volcanoes around the world. To reduce the risk to those people, volcanoes can be monitored, so we can predict when they might erupt, and put protection measures in place. There's lots of key words in those paragraphs, so let's have a little look at what they mean. To monitor, means to record physical changes, such as earthquake tremors, when we've got movement in the Earth's crust to help forecast or predict when a natural hazard will strike. Predictions are attempts made by scientists to forecast or say when and where a natural hazard will strike. And finally, protection. These are the actions taken before a natural hazard strikes to reduce its impact. If you want to, you could pause the video now, so you can write down those key words. Excellent. Well done for doing that and make sure you try to remember them, because we're going to be using them throughout today's lesson. So, warning signs of a volcanic eruption. These are earthquake activity or seismic tremors. That's the shaking that you get in the Earth's crust, as those tectonic plates move. We get the shape of a volcano, which can change. The water temperature, can change. Certain gases may increase or decrease, so we get changes in the gas concentration, and in soil pH, or how acidic it is. Volcanologists, who are the scientists that study volcanoes, study changes in these warning signs to predict when and where an eruption will take place. We're going to go through each of these warning signs, so you can understand a little bit more about them, and maybe become young volcanologists yourselves. So the first one we're going to look at is earthquake activity, or seismic tremors. We've got some more keywords here, that's important for us to understand. Seismic activity is anything relating to vibrations in the Earth's crust, that's linked to tectonic activity, which is earthquakes and volcanoes as well. So that's the shaping in the Earth's crust, caused by the movement of plates, or caused by lava being pushed up through cracks in rocks. A seismometer, which you can see on the diagram here, is the back, cylindrical item. This is an instrument used to detect sudden movement, and those vibrations in the Earth's crust. And we've got a seismograph, which records information from the seismometer. So the seismometer is buried in the ground near the volcano, and it transmits or sends signals back to the seismograph, to be able to record what's going on with the vibrations in the Earth's crust, or the seismic activity. Pause the video to make sure you've understood these terms, and written them down. Excellent. Well done. So, we're now going to watch a video. What I'd like you to do is pause again, very quickly, so you can copy down these questions. Then listen out for the answers in the video. So pause now and copy them down. Thanks for copying those down. It should help to focus you as you watch this next video. Listen and look carefully. Now the seismograph has an intersection, and a needle, and it spreads in through to the needle, and you can see this needle moving backwards and forwards, detecting any tremors in the Earth, okay? Now that movement is from the seismometer, which is in location, out in the wilderness, in the volcano, and it detects different types of seismic tremors. So each line here, this moves across, and each line represents five minutes in time of tectonic and seismic activity. Okay? And so each graph represents 12 hours worth of activity, and this is a seismograph of the 12 hours of Mount Lokon, overnight, last night. And we can see those different types of, kind of patterns made by the different types of seismic waves, that are transmitted to the seismograph. And we've got some very broad, wide ones here, which are more kind of seismic waves, earthquake tremors, and then these shorter bursts, tend to be related more to volcanic activity. Okay, so this, I'm very excited. It's very exciting piece of equipment. I've never actually seen it in real life, but your seismometer, feeding through to a seismograph, helping save people's lives, and we're-

As you can see, I was just a little bit excited about seeing a seismograph working in real life, recording that information to help try and save people's lives, but it was also a great opportunity for me, to understand more, about what the scientists and volcanologists do, to be able to predict volcanoes. And so I asked you some questions. The first one was where do you find a seismometer? That's the black cylindrical item that you saw in the video. You find a seismometer buried in the soil, close to the volcano. It's about one metre underneath the ground, and it's there to detect those seismic tremors, or any movement in the Earth's crust, which can indicate that the volcano is about to erupt. How does a seismograph record the information? Well, if you remember, the seismograph is the instrument that has the piece of paper wrapped around it, that rolls round and round. And it feeds ink through the needle, onto the paper, going backwards and forwards, recording those tremors in the Earth's crust. How many different seismic patterns are shown on this example? I showed you one of the graphs that had been drawn, and on this, we had two types. We have the longer seismic tremors, which were shown by broader strokes of the needle backwards and forwards, and shorter volcanic bursts. So we had shorter tremors that were much closer together, volcanologists and scientists study this, so that they can see if there's any difference. All active volcanoes, normally show some element of seismic tremors, but when they become more frequent or larger, that's when the volcanologists send out a warning to the local people to evacuate, or leave the area to try and save lives. Scientists also study the shape of the volcano, and if there are any changes, this could indicate a volcanic eruption. To explain this, I've drawn some diagrams. We can see we've got a volcano cross-section on the screen here. This volcano is shaped like a cone, and it has a channel or a main vent running up from the magma chamber, where that hot liquid rock is stored, all the way to the crater at the top of the volcano. We also have a secondary vent coming out to the side. Now, as the magma travels up those channels, sometimes, it causes the surface to bulge outwards and change shape, as you can see on the diagram. So often, as the magma reaches the surface as a lava, the lava solidifies as it cools down. This can block those channels or vents, a bit like a cork in a bottle, and the magma builds up behind it, and the pressure builds up and up, and it pushes out, and changes the shape of the volcano above it, pushing out the rock and the Earth. If we zoom in on this particular section, we can see the magma pushing out the side of the volcano. We can also see a tilt metre here. Underneath the surface, there's a tilt metre. Now this is the instrument that measures the shape of a volcano. It measures any changes in the shape. If we zoom in on this bit, I can show you how. So you can see a ball in the middle of the tilt metre here, right down that central line. This is when that particular tilt metre is vertical. If the land moves, and pushes that tilt metre to the side, you can see that the line still remains down the middle, but the ball has moved position relative to it. So as the tilt metre is moved, the ball inside moves as well, and this is monitored to detect changes in volcano shape. So a tilt metre detects those changes in the shape of a volcano. Pause the video now, if you want to copy down any of the information on this page. At the very least, you need to get down the definition of what a tilt metre is Excellent. Well done for doing that. Let's see how else volcanologists and scientists study volcanoes, and what warning signs they can see. We have three more warning signs to consider. The first is water temperature. You can see here, a picture of a pool of water, close to a volcano. And this pool of water has been heated up so much that it's got steam rising from it, a bit like you get steam rising from a boiling pan on the surface of a hob. Now the increase in volcanic activity means that a lot of that hot liquid magma is being pushed towards the surface. Now, actually, what happens is that hot magma heats the rock above it in the crust. And it's that hot magma, the closer to the surface of the crust it is, the hotter it's going to be. So therefore, higher temperatures in water that are nearby a volcano often indicate eruption. We also get changes in gas concentration, so the amount of particular gases. You can see here, a picture of a volcanologist, a scientist going close up to the volcano with an instrument to test how much gas is in that stuff that's coming out of a volcano. Higher concentrations of gases, such as sulphur, mean that there's likely to be an increased volcanic activity and an imminent. or a near eruption. We also get changes in soil pH, or acidity. Increased volcanic activity means that there's more sulphur in the soil, which lowers the pH and makes it more acidic. Therefore, this can also be tested to let us know and predict when a volcano might erupt. Volcanoes give off a fare few warning signs that they're about to erupt. We've looked at a handful of them today. I want you to read through these statements and decide which two statements are true. Is it option one, increased volcanic activity leads to higher water temperatures. Option two, a tilt metre does not detect when the volcano changes shape. Option three, increased volcanic activity leads to higher concentrations of sulphur. Or option four, increased volcanic activity leads to higher soil pH. Excellent. I hope you've had a guess. The answers are option one. We get increased higher water temperatures or increased water temperatures because the magma, that hot liquid rock is closer to the surface of the crust during or when a volcano is about to erupt. This heats up any water that's found lying on the surface Option three is also correct. Increased volcanic activity leads to higher concentration of gases, such as sulphur. Hopefully, you realised that option two was not correct. This is because the tilt metre is the instrument that is used to detect changes in a volcano shape. Option four is also incorrect. What actually happens is an increased volcanic activity leads to lower, or more acidic pH levels in the soil. Well done if you managed to get them right. It's all very well knowing when and where a volcano might erupt, but we also need to prepare and warn those people that might live in the area. If we know a volcano is going to erupt, we need to prepare to take action. We can set up an exclusion zone, so an area around the volcano, that's the danger zone. We can have an evacuation plan, so that residents that live in that danger zone know when they need to leave and where they need to go. You can see here a sign of an evacuation route, telling residents where to flee to. In some countries, emergency services also have a response plan to help support residents. And one key thing that local people that live near a volcano can do, is have a survival kit of basic provisions. Let's look at one of these in real life. So exclusion zones and evacuation plans in Mount Agung, in Bali, Indonesia. Mount Agung is an active volcano in Bali, Indonesia. In 2017, it showed warning signs of an eruption. There were many more seismic tremors in the Earth's surface, close to the volcano, suggesting there was movement of magma and lava underneath pushing apart and moving the crust. There was also a higher concentration in gases, such as sulphur. This meant that volcanologists, scientists and the local authorities got together to come up with a plan. They told 100,000 residents to evacuate or leave the 10 kilometre exclusion zone. You can see on the diagram here, that we've got some orange lines, misshaped lines, which represent the predicted channels, where lava would flow down. So these would be the danger zones. Because of the amount of seismic activity, residents within the 10 kilometre evacuation zone were told to leave. This is everyone that lived inside this red circle here, and these extra bits added on the edges where those lava flows, or larva channels are thought to be. Indonesia obviously also needed to let the local residents know what to do. They gave out lots of information to educate people, so that people knew what and why they have to leave their area. That's really important so that people actually listened to the authorities , and do as they're told, to help protect themselves. One thing that happens in a lot of countries, is that emergency services prepare. In some countries, emergency services are given special training to respond to a natural hazard, such as a volcanic eruption. So let's see what we've learned about preparation, and Mount Agung in Bali, Indonesia. I want you to complete this paragraph. I've put some of the words, below, to help you out, so pause the video now to complete your task, and press resume when you've finished. Excellent. Well done. Let's see, did you get it? Mount Agung is a volcano in Bali in Indonesia. Give yourself a tick, if you managed to get Indonesia. and maybe two ticks, if you wrote down the island, Bali, as well. In 2017, it showed warning signs of an eruption. There was a big increase in seismic activity and gases. It doesn't matter which way round you've written these two, but give yourself a tick for one each. The government set up an exclusion zone, a danger zone where people were warned to evacuate. So the government set up an exclusion zone within 10 kilometres of the volcano. It asks, and this is the one that I'll be really impressed if you got it, because it wasn't on the list, at the bottom. It asked 100,000 residents to evacuate the area. Give yourself two ticks, if you managed to get both of those. In some countries, when volcanic eruptions are very bad, the emergency services are trained to respond effectively. Well done, if you managed to get those right. The last thing we're going to look at is what individuals can do to help themselves. They can prepare a survival kit of basic provisions. Can you guess what would be a good idea to pack from these images? Hopefully, you've managed to get a few of them. So we've got number one, which is a torch or flashlight. Often during natural disasters, such as volcanoes and earthquakes, the electricity supply gets shut off. So therefore a torch can be really useful. We've also got a radio, but it's not just any radio, it's a windup radio. This means that it doesn't need to rely on electricity, or batteries to run. We also have a face mask. This is particularly important because of the ash and gases that escapes from the volcano during an eruption. We also need a bit of a food supply. Now here, we've got food that's packaged, and it's not food that needs cooking. This is because quite often, electricity or gas will be cut off to people's houses, so they won't be able to cook their own food. We've also got a first aid kit. Often people get hurt or injured during an eruption, and so it's important to have things to help them. Now there's one really important thing that's missing. Can you think what it is? That's right. It's water. Now, often water gets contaminated or becomes dirty during an eruption because it might get filled with ash, or the pipes might get broken. Therefore it's really important to have some fresh water, to be able to drink and keep hydrated. So, in today's lesson, we've been looking at how we can predict, protect and prepare for volcanic eruptions, and we've learned about some of the different warning signs that volcanoes show, which indicate an eruption is about to happen. Those mean that people that live in the area can be warned, and told to evacuate, and we can help to save people's lives. If you want to share your work with Oak national, please ask your parents carer to share your work on Instagram, Facebook, or Twitter, tagging @planetearthrowl, @OakNational and #LearnWithOak.

Exit Quiz: How can we predict, protect and prepare for volcanic eruptions?

Completed: How can we predict, protect and prepare for volcanic eruptions?

This lesson will look at how we can predict, protect and prepare for volcanic eruptions.

Geography

How can we predict, protect and prepare for volcanic eruptions?

Introductory Quiz

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