There was no central eruption point, instead the eruption happened all the way down the length of a 1. The amount of thermal energy the eruption produced was tremendous; equivalent to the energy of a Hiroshima sized atomic bomb being set off every 2 minutes! The eruption lasted for 6 months, eventually stopping in February By then it had produced 1. Because there was no interaction with ice, only a minute amount of ash was produced. However it did release around 11 M tones of SO 2 — more than the whole of Europe produces in a year!
Plate tectonics: investigating and visualising our dynamic earth
This was the main hazard of the eruption as the gas was blown around on the wind affecting large numbers of the population. Ground level concentrations of SO 2 exceeded health limits over most of Iceland for days to weeks, with the high concentrations of SO 2 can cause breathing difficulties and eye irritation. It's very important to carefully monitor volcanoes to try and understand what kind of eruption they might have and what hazards that could present. Measuring the tiny earthquakes that happen in volcanoes, gives us a powerful tool we can use to see inside the earth and track where molten rock is moving beneath the surface.
Keeping track of these observations can help inform public bodies, aiding their decision making and their planning of hazard mitigation strategies. The population of Iceland is , or about the population of Reading. Two-thirds of the Icelandic population live in the capital city - Reykjavik. More than a million people visit Iceland each year on holiday , about 3 times its population. All of Iceland's heating and electricity is generated renewably, either from hydroelectric or geothermal methods.
Volcanic eruptions from the Icelandic volcano Hekla can be anticipated by an earthquake swarm 30 minutes before the eruption. Not much use if you are on the volcano but enough time to get the news helicopters in the air!
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Holuhraun lava flow covered an area of 84 square km. Holuhraun lava fountains were up to m high , taller than Big Ben! Holuhraun released vast amounts of thermal energy, equivalent to: 1st month - releasing a Hiroshima atomic bomb every minute on average over the 6 month long eruption - releasing a Hiroshima atomic bomb every two minutes.
Holuhraun released million tonnes of sulphur dioxide - equivalent to European annual emissions. The volcano seismology group fr om the University of Cambridge were the first people to see the eruption with their own eyes. They tracked the eruption in collaboration with the Icelandic Met Office and the University of Iceland during the first weeks of the eruption before they had to reluctantly go home. Instruments were placed so close to the eruption site by the University of Cambridge that they had to be rescued from the advancing lava meters away!
The intrusion and subsequent lava flow was monitored in real-time by more than seismometers, more than 30 GPS instruments, 3 Satellites and 4 webcams. The Eyjafjallajokull eruption shot ash 35, feet into the air. The Eyjafjallajokull ash cloud grounded over , flights.
The magnitude scale of earthquakes is logarithmic. This means every time you go up one on the scale, the earthquake is 10 times bigger. The only reason we know anything about the internal structure of the earth is because earthquake waves travel through it and contain information about the material they travel through. The united state geological survey USGS estimates that several million earthquakes occur in the world each year. Many go undetected because they hit remote areas or have very small magnitudes.
We do get earthquakes in the U. The largest earthquake to ever happen in the UK was a magnitude 6. The most damaging earthquake in the UK in recent history was in near Colchester. About 1, different volcanoes have erupted over the past 10, years, but only about 60 erupt each year. On any given day, there are about 20 volcanoes erupting somewhere in the world.
Earthquake and Volcano Distribution - Dynamic Earth: Plate Tectonics
Seismometers record ground motion and earthquakes. When the earth moves the base of the seismometer moves as well, but the free swinging mass stays still. Check out the videos below to see this principle in action. Originally a pen was attached to the mass and the base had a roll of paper to record the relative movement between the moving base and the stationary pen. Now systems tend to use magnet, which are free to move within a coil of wire — this creates an electrical current which is measured and converted into amount of ground movement.
Many modern devices like Macs and iPhones have small seismometers built into them, so they can detect motions and adjust the screen accordingly. Just type seismometer into a search on your app store and choose from lots of the free downloadables! We download the recorded ground motion data and carry out maintenance to ensure everything is working properly. We also often move seismometers to more useful places for the next years research plans. Seismometers are deployed by digging a big hole and putting them in the ground, if possible onto a solid bit of rock so that they pick up vibrations and tiny movements well.
They need to be completely level which we check by looking at the spirit level on top , so sometimes the really sensitive ones are placed on top of a flat paving slab. They need to be kept dry, so are often buried in plastic barrels. They need to be pointing towards the north to make it easier for us to tell what direction seismic energy is coming from.
In Iceland this is really easy since all our seismometers are deployed in a barren, volcanic desert. The seismometers, like most machines, need a power source to keep them going. Instead we use solar panels to generate electricity from the sun. Unfortunately because Iceland is so far north, for lots of the year there is very little sunlight. There is also lots of snow in the winter which can bury the solar panels.
The seismometers will record the tiny movements of the ground, sampling the motion up to times per second. This information is stored within the memory of the seismometer until we come back and download it. Some seismometers stream the data live via satellite connections, but this generally requires more power than a few solar panels and batteries can provide.
The Icelandic Met Office power several of our instruments and use them for real-time monitoring. Despite the fact that the Earth is predominantly solid, in certain circumstances the solid Earth can melt to form magma. In Iceland two of the factors which can cause melting and magma creation happen in the same place. This allows the solid material beneath the crust to rise upwards, and reduces the amount of pressure on it, allowing it to melt and form magma. Thus new material is formed and moves outwards in a process known as rifting a sea floor spreading.
This is why there are volcanoes all the way along the centre of the North Atlantic Ocean, where the Eurasian and N. American tectonic plates are pulling apart. So why then, is Iceland more volcanically active than the rest of the plate boundary? It is thought that Iceland is also underlain by a hot upwelling rising from the core of the Earth upwards, which is part of a convecting system within the solid Earth.
This means that under Iceland it is also hotter than in other parts of the world. This also causes the solid Earth to melt and form magma. The combination of a plate boundary releasing pressure and an underlying hot upwelling, mean that Iceland has large amounts of magma generated and thus large numbers of volcanoes 30 active volcanic systems! When an earthquake happens energy travels outwards as waves in all directions, like a ripple spreading across the surface of a pond.
There are two main types of earthquake seismic waves: P waves which have a squashing together longitudinal motion and are faster, and S waves which have a side to side transverse motion and are slower. As the wave moves outwards when they pass a seismometer the ground will shake a bit and the seismometer will record the ground motion.
Since the P wave is faster, the seismometer will first detect a little wobble of the ground when the P waves goes past and a bit later another wobble of the ground when the S wave goes past. It is possible to work out how long the wave has been travelling for, and thus how far away the earthquake occurred, by looking at how long it takes the two waves to arrive at the station. By doing this at lots of different seismometers in different locations we can work backwards to find out the earthquake source location. The animation below shows this concept in action.
Particles of volcanic glass, which make up a component of volcanic ash, often have melting points below engine internal temperature. In-flight, particles will immediately melt if they go through an engine. Going through the turbine, the melted materials are rapidly cooled down and stick on the turbine vanes, and disturb the flow of high-pressure combustion gases. This disorder of the flow may stall the engine, in the worst cases.
The Eyjafjallajokull eruption forced the closure of European airspace grounding , flights because of the worries that ash would damage the plane engines. Images below show the ash cloud - being blown away from Iceland across the Atlantic, and at the eruption site. Many things determine whether an eruption will be explosive or not. The most important ones are: if there is ice interaction and how runny or thick the lava is how viscous it is. The viscosity runniness of magma is a major factor in controlling whether or not an eruption will be explosive.
This is because viscous magma can trap gases which are in the magma, causing a build-up of pressure until the volcano can no longer contain it and a violent explosion releases the built up pressure, whereas fluid magma allows gases to escape easily. Lightning flashes sometimes occur above erupting volcanoes. In volcanic eruptions there are two possible sources for generating lightning. One source is the stationary electric charge caused by ash particles rubbing together in dense clouds near the ground.
The other source of lightning happens near the stratosphere, nearly 12miles 20km above the Earth's surface. When a volcanic ash cloud rises this high, the water vapour carried in it starts to freeze and form ice crystals which can rub against each other to build up charge and produce lightning, like in a normal thunder storm.
Find out more here. Volcanic lighting, image by Oliver Spalt. Both the volcanic earthquakes and fracking induced earthquakes are, mostly, very tiny less than magnitude 0 , and are too small to be felt by humans, but there are lots of them. This is the only way they know what the fractures look like underground. This is very similar to the way we track the tiny magma induced earthquakes to tell us where magma is travelling underground in volcanic systems.
It has been suggested that fracking could cause larger magnitude earthquakes if fracturing fluid lubricates big pre-existing weaknesses which are already under stress see section below for more details. A number of human activities can cause induced seismicity including mining, construction of large water reservoirs, waste water disposal by injection and fracking. Fracking is known to cause large amounts of microseismic activity with potentially much more which is too weak to be recorded by seismic instruments on the surface.
However, there have been tentative links to larger magnitude earthquakes which some claim may have been caused by fluid injection, including a magnitude 5. However making direct links to what sets off a primed fault which is likely to slip at some point, is very difficult, so it is hard to say definitively if such events can truly be linked to human fluid injection or not. This highlights the importance of a good geological understanding of an area and its pre-existing faults before fracking operations are given the go-ahead. The earthquakes in Blackpool which have been linked to fracking were magnitude 2.
Magnitude 2. It is thought that these were caused by lubrication of pre-existing small scale faults m x m which moved approximately 1cm. It is thought that the maximum magnitude seismic events likely to be caused by fracking in the UK are still likely to be smaller magnitude than naturally occurring British earthquakes and those induced by coal mining. The conclusion on the UK research report from the Royal Society of Engineering and the Royal Society, concluded that the health, safety and environmental risks of fracking can be managed effectively in the UK, by implementing and enforcing best operational practice.
However, they made several recommendations including calling for more research on the carbon footprint of shale gas extraction. If you would like to learn more about fracking earthquakes and fracking in general we would recommend the websites listed below. The websites shown are selected for their science based nature and should contain impartial unbiased information:. Geomechanical Study of Bowland Shale Seismicity independent report on Blackpool fracking related earthquakes — Nov Review of Hydro-fracking risk and management conducted by the Royal Society and the Royal Academy of Engineering , Research briefing paper on hydraulic fracturing for the House of parliament — However, the crust is not a complete solid outer shell - it is cracked and split into many separate pieces which all fit together like a jigsaw puzzle.
We call these interlocking pieces tectonic plates.
- Plate Tectonics, Volcanoes, and Earthquakes.
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It is here at plate tectonic boundaries that the majority of earthquakes and volcanoes are located. Volcanoes occur at plate tectonic boundaries because they provide special conditions which allows the normally solid mantle the layer of the earth beneath the crust to melt see section — where does magma come from? The majority of earthquakes occur at plate tectonic boundaries because moving large chunks of rock past each other is very difficult, and there is a lot of friction. But the remainder of the plates continue moving, causing more and more pressure to build up on the stuck locked section.
Since there are lots of volcanoes at plate boundaries, there are also earthquakes related to the movement of magma in volcanoes, such as the ones we talk about in our exhibit Explosive Earth. But volcanic earthquakes are usually very very small, releasing tiny amounts of energy compared to big tectonic earthquakes. The majority of the Earth is solid rock. There is no layer of magma lying underneath our feet.
The outer layer, the crust, is cold brittle rock; the next layer, the mantle, is very hot, squishy rock but it is still solid. But if the majority of the Earth is solid rock, then where does magma come from, and how is it formed? The ground may split; pouring forth molten rock, smoke, and ash that darkens the sky for hundreds of miles. Even the mountains, which seem timeless, are slowly growing in some ranges. The theory that describes all of these processes and explains why they occur when they do is called plate tectonics.
Faults and Earthquakes
In some regions of the world, particularly on the ocean floor, there are areas where the plates are spreading apart. As they spread, magma bubbles up and hardens, creating new continental crust.
In other areas, different tectonic plates are sliding toward each other. The motion of tectonic plates colliding, separating, or just sliding along next to one another is responsible for a range of tectonic activities including earthquakes, volcanoes, and the formation of mountains. When tectonic plates grind along one another they create earthquakes.
Areas like this are called transform plate boundaries. As the plates grind along they build up potential energy along the fault, which is occasionally released in the form of vibrations. The distribution of transform boundaries around the world is a major predictor for the distribution of earthquakes worldwide. Some of our mountains are very old. The Appalachians formed hundreds of millions of years ago and today are eroding away, however, other mountain ranges, such as the Himalayas are young and still growing.
The motion of plates colliding with one another is responsible for the creation of mountain ranges. As the heavier plate sinks and is exposed to high temperatures, it releases volatile compounds, including water, in a gaseous state. These gases force their way upward and some of the solid rock in the plate melts, creating new magma.