Friday 12 October 2012

How are volcanoes monitored?

Below is a report by B.Slawinski, a year 10 pupil on his research into how volcanoes are monitored. It covers overall types with their individual details very well.

There are many different ways and techniques to monitor volcanoes, they are; seismicity, ground deformation, geophysical measurements, hydrology, gas and lastly remote sensing. In this fact file I will be showing when each of these techniques are used when they are used and how effective they are.

Seismicity

Seismic activity (earthquakes and tremors) always occurs as volcanoes awaken and prepare to erupt and are a very important link to eruptions. Some volcanoes normally have continuing low-level seismic activity, but an increase may signal a greater likelihood of an eruption. The types of earthquakes that occur and where they start and end are also key signs. Volcanic seismicity has three major forms: short-period earthquake, long-period earthquake, and harmonic tremor. Short-period earthquakes are like normal fault-generated earthquakes. They are caused by the fracturing of brittle rock as magma forces its way upward. These short-period earthquakes signify the growth of a magma body near the surface and are known as 'A' waves. Long-period earthquakes are believed to indicate increased gas pressure in a volcano's plumbing system. They are similar to the clanging sometimes heard in a house's plumbing system, which is known as "water hammer". These oscillations are the equivalent of acoustic vibrations in the chamber, in the context of magma chambers within the volcanic dome and are known as 'B' waves. Harmonic tremors are often the result of magma pushing against the overlying rock below the surface. They can sometimes be strong enough to be felt as humming or buzzing by people and animals, hence the name. Patterns of seismicity are complex and often difficult to interpret; however, increasing seismic activity is a good indicator of increasing eruption risk, especially if long-period events become dominant and episodes of harmonic tremor appear.

Gas emissions

As magma nears the surface and its pressure decreases and therefore gases escape. This process is much like what happens when you open a bottle of soda and carbon dioxide escapes. The main gases released are Sulphur dioxide and increasing amounts of it h erald the arrival of increasing amounts of magma near the surface. For example, on May 13, 1991, an increasing amount of sulphur dioxide was released from Mount Pinatubo in the Philippines. On May 28, just two weeks later, sulphur dioxide emissions had increased to 5,000 tonnes, ten times the earlier amount. Mount Pinatubo later erupted on June 12, 1991. On several occasions, such as before the Mount Pinatubo eruption and the 1993 Galeras, Colombia eruption, sulphur dioxide emissions have dropped to low levels prior to eruptions. Most scientists believe that this drop in gas levels is caused by the sealing of gas passages by hardened magma. Such an event leads to increased pressure in the volcano's plumbing system and an increased chance of an explosive eruption.

Ground deformation

Swelling of the volcano signals that magma has accumulated near the surface. Scientists monitoring an active volcano will often measure the tilt of the slope and track changes in the rate of swelling. An increased rate of swelling, especially if accompanied by an increase in sulphur dioxide emissions and harmonic tremors is a high probability sign of an impending event. The deformation of Mount St. Helens prior to the May 18, 1980 eruption was a classic example of deformation, as the north side of the volcano was bulging upwards as magma was building up underneath. Most cases of ground deformation are usually detectable only by sophisticated equipment used by scientists, but they can still predict future eruptions this way. The Hawaiian Volcanoes show significant ground deformation; there is inflation of the ground prior to an eruption and then an obvious deflation post-eruption. This is due to the shallow magma chamber of the Hawaiian Volcanoes;

Hydrology

There are 4 main methods that can be used to predict a volcanic eruption through the use of hydrology: Borehole and well hydrologic and hydraulic measurements are increasingly used to monitor changes in a volcanoes subsurface gas pressure and thermal regime. Increased gas pressure will make water levels rise and suddenly drop right before an eruption, and thermal focusing (increased local heat flow) can reduce or dry out aquifers. USGS scientists have developed an inexpensive, durable, portable and easily installed system to detect and continuously monitor the arrival and passage of debris flows and floods in river valleys that drain active volcanoes. Pre-eruption sediment may be picked up by a river channel surrounding the volcano that shows that the actual eruption may be imminent. Most sediment is transported from volcanically disturbed watersheds during periods of heavy rainfall. This can be an indication of morphological changes and increased hydrothermal activity in absence of instrumental monitoring techniques. Volcanic deposit that may be placed on a river bank can easily be eroded which will dramatically widen or deepen the river channel. Therefore, monitoring of the river channels width and depth can be used to assess the likelihood of a future volcanic eruption.

Remote Sensing


Remote sensing is the detection by a satellite’s sensors of electromagnetic energy that is absorbed, reflected, radiated or scattered from the surface of a volcano or from its erupted material in an eruption cloud. 'Gas sensing: Sulphur dioxide can also be measured by remote sensing at some of the same wavelengths as ozone. TOMS (Total Ozone Mapping Spectrometer) can measure the amount of sulphur dioxide gas released by volcanoes in eruptions Thermal sensing: The presence of new significant thermal signatures or 'hot spots' may indicate new heating of the ground before an eruption, represent an eruption in progress or the presence of a very recent volcanic deposit, including lava flows or pyroclastic flows. Deformation sensing: Satellite-borne spatial radar data can be used to detect long-term geometric changes in the volcanic edifice, such as uplift and depression.

Wednesday 10 October 2012

Largest Earthquake Ever Recorded?

The question that I wanted to answer was "What was the largest earthquake ever recorded?". See below for the information I found out:
The largest earthquake ever recorded was in Valdivia in Chile. It occurred on the 22nd May 1960 and was recorded at 9.5 on the Richter scale. It occurred in the afternoon at 15:11 local time. The earthquake also resulted in a tsunami which affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia and the Aleutian Islands in Alaska. The epiccenter was near Lumaco around 570km south of Santiago. The waves reached up to 25m in height. Two days after the earthquake, a volcanic vent close to Puyehue volcano erupted. This was caused by the Nazca Plate being subducted underneath the South American Plate on the Peru-Chile Trench.

Tuesday 9 October 2012

Mt.Vesuvius eruption 79 AD

For my research today, I tried to answer the question of why Pompeii was so badly affected by the eruption of Mt.Vesuvius in 79 AD. Pyroclastic flows swept the city and everything was buried under an extremely hot layer of ash. The city was preserved in time and there was one thing which astounded archaeologists the most when they rediscovered the city. This was the human remains which were found on the site. Although the exact number of people who died in the eruption is unknown, it is predicted that a large proportion of the city's population was killed. There are a few reasons which could explain why the eruption had such a big impact on the city's population. Firstly, although the locals were aware of the plumes of smoke rising from the volcano (a journal was found documenting the signs leading up to the eruption) no precautions were taken. They thought of it as the gods letting off steam therefore no actions were taken until it was too late. Like volcanic eruptions in the modern world, tremors and seismic activities were felt leading up to the eruption. They also chose to ignore this as they were unaware of what could come next. When the volcano finally erupted, the people were caught by surprise and didn't know how to react. Some chose to flee the city and it is likely these people survived as the only affect on them was ash deposits. Those who chose to hide in the safety of their homes were the ones killed. As the pyroclastic flow swept the city, the infrastructure was unable to withstand the speed and temperatures and thus people were buried and burned. The main reason why the eruption of Mt.Vesuvius was so devastating was the lack of awareness. In the modern world, this could still be the case particularly in LEDCs. If large volcanoes are not monitored, locals could be at an increased risk as precautions and responses will not be taken to ensure they are safe. This shows that raising awareness and having an efficient system of response is vital in reducing the impacts of natural hazards, even in the modern world.



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My question was, how do explosions in volcanoes happen? What are the triggers?

 

The build up of hydrostatic pressure (pressure from magma at higher levels in the system) and the expansion of gas shoot lava high into the air. These lava fountains are commonly a few tens to hundreds of feet (meters) high. Less common are fountains that reach over 1,000 feet (300 m) in height. The highest 1959 lava fountain at Kilauea Iki reached 1,900 feet (580 m) in height. Thats 5 and a half football pitches.

 

Another example of an explosive type of eruption. Mount St. Helens in 1980 was an example. Such an eruption is driven by gas accumulating under great pressure. Driven by hot rising magma, it interacts with ground water until the pressure increases to the point at which it bursts violently through the over mantle of rock. In many cases, the rising magma will contain large quantities of partially dissolved gas. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. With the sudden release of pressure following the initial explosion, the gas comes out of solution violently and explosively.

 

 

Wettonga tribe, Northern Australia




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Earthquake In England?

I was wondering why there are occasional EQ's in the UK even though we are not close to a plate boundary, where science tells us EQ's should occur.

In my research I found that the key to it all lies in the African and Eurasion plates movement. These have created multiple fault lines as shown in this image -


They occur more than we think - http://www.earthquakes.bgs.ac.uk/ - this shows the amount over the last 50 days with more detail within them.

Even the Daily Mail have got involved - http://www.dailymail.co.uk/sciencetech/article-1312608/UK-overdue-earthquake-kill-scores-people-moment.html - A slighlty exaggerated state of event but good detail nonetheless.

J.P.Strode

Are there volcanoes on other planets?

Are there volcanoes on other planets?                                                                  Olympus Mons - Mars
·         Dead volcanoes are found on Venus, Earth and its Moon, and Mars. Active volcanoes are located on Earth, Jupiters Io, and possibly on Venus, on Saturn’s Titan, and on Neptunes Triton. Terrestrial and outer space volcanoes share some common properties.

·         Mars also has many distinctively volcanic features, including the largest volcano in the solar system, Olympus Mons, which towers 16 miles high over the Martian landscape. "If volcanism had occurred up until the last 1% of geologic time, it is very unlikely to have stopped," McEwen says. "We just haven't observed anything that is a smoking gun on either Mars or Venus.”

·         Volcanoes also shaped Mercury. There, however, the activity appears to have stopped operating early in the planet's history, billions of years ago. On our moon, too, volcanism operated early and then shut off sometime around 3 billion years ago.

Largest earthquake to happen with limited effect on human life?

 

Although these are very debatable because there can be no constant measurement of the earthquakes that go on under the entire ocean but the 1938 Banda Sea earthquake is up there. With a magnitude 8.5 on February 1 there was no deaths and the biggest problems were a pendulum clock stopping and glassware breaking on Banda and Kai islands. Bana Sea is near Indonesia to locate the example.

 

If you then want to contrast with some others then you can take Haiti, which was only magnitude 7.0 in June 2010 and killed 92,000. You could always take Kashmir 2005, killing 79,000, and was still only a 7.6. this means that it is almost 100 times bigger than Kashmir and still killed nobody.

 

Also follow @quakestoday for good infomation about the vast majority of earthquakes!

 

 




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Japanese Debris in USA

There is a very interesting article on Japanese debris from last year's tsunami washing up on US beaches below:

http://www.bbc.co.uk/news/magazine-19812373

This may support long term environmental effects well and also expands the scale of effects in terms of area beyond what we may have originally discussed.

Monday 8 October 2012

Nyoragongo Eruption 2002 Fact File

Great link below for infromation about the eruption if you look at the 8th section gives some detail of the effects.
http://nyiragongo.com/2002.html

Great website for Nyiragongo 2002 CASESTUDY

This is a day by day, as it happened account of the volcano in 2002. Great resource and very interesting!



http://nyiragongo.com/2002.html

Saturday 6 October 2012

Volcano Live - Review

Great set of videos to demonstrate the fascinating volcanic activities that take place around the world. One fact that I found extremely interesting and extraordinary: The lava flows that came from Kilauea were sometimes the height of the Empire State building, and just the shear amount of ash that comes out of the volcano is unbelievable.

I would say that, perhaps a few computer generated images to show what happens inside the volcano during an eruption would have been amazing to see. Over all though, an excellent, in depth account of some useful case studies.

DT

Friday 5 October 2012

Review of Volcano Live

1.       The most interesting fact you have learned from the documentaries.

 

I enjoyed the documentaries, especially the last one (4/4) that looked particularly good case studies and information about monitoring of the volcanoes. What I did found very interesting is the measurement to do with the sulphur dioxide (SO2) gas and what effect that has on the likelihood of an eruption. This was very well explained because I learnt that the different gases get released at different levels and sulphur dioxide is the one let off most near the surface. It is also interesting how they measure the gas with ultra violet light being emitted and then absorbed by the SO2 if there was a lot of it there.

2.       What you would have liked to see covered in the programmes.

 

I would have liked to have seen more case studies; I was particularly disappointed with the third one as it covered many case studies in little detail but not many in good enough detail to be useful. I would have also liked to have seen some longer term impacts on show. They seemed to focus a lot on the short term and the management part rather than longer term.

 

James Stroomer



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Thursday 4 October 2012

My Top Fact

This fact is linked to the video 2/4 of The Volcano Live Series and is about pyroclastic flows:
Did you know they could travel across water most likely due to the way in which the pumace sits on the surface like a raft for the hot ash to bounce off.

Interesting point on Volcano Live BBC video

I was suprised to see in the second of four videos in the volcano live series that a whole landscape could be completely covered in what looked like a grey coloured snow. It was actually Ryolite. This is a thick lava that when moving and heated, produces large amounts of white ash. This white ash is from sylicate and after a large eruption like puyehue in chile in 2011 can completely cover a landscape.

I would have liked to have seen more depth in the places used. Some were briefly mentioned and I feel there was a lot more information that could have been included that was not. Some were good yet not in depth enough with just this resource to form a strong casestudy.

Volcano Live

Amazing fact from Volcano Live #1... apparently it is perfectly okay to go for a swim in a lake of pumice. Not top of my to-do list but each to their own, I guess.....? It was very interesting to see that many people actually use the fact that pumice floats in order to go for a swim! Also it is apparently very good for your skin. There were many intersting facts in the programs but this stood out for me as I had absolutely no clue about it. I would have thought it would be a place to avoid but am very mistaken indeed!

The programs were great; I ended up watching all 3 on clickview and the only thing I would have liked to have seen which wasn't there was maybe more reference to how the volcanoes actually form and the difference in formation, caused by different plate boundaries. Other than that, pretty faultless I would say!

Volcano Live

Over the past few days I have the 3rd and the 4th episode of the Volcano Live series. Personally I think that the 4th episode was the best as it gave a lot more detail about the numerous volcanoes around the world.

The piece of the documentaries that intrigued me the most was the part where a select few volcanologists travelled to Mount Erebus in Antarctica. The group travel to Mount Erebus every year to study the lava lake that is present in its crater. Here they set up equipment that studies the movement of the lava and the gases that are released. They would locate themselves right on the lip of the crater, pitching tents a matter of meters from a drop leading to a huge lava lake. The lava lake is extremely active and has minor explosions almost every week meaning that the volcanologists were in real danger. Whilst they were there the lava lake exploded sending hot material flying. This material nearly took out one of the cameras and a tent. I find it intriguing how there is a massive contrast in Antarctica, between the cold and arid environment that is the Antarctic, compared to a extremely hot and dangerous volcano/lava lake.


The only thing that I would have like to seen added to the documentaries would be more about how the inner workings of the earth affect each situation and more footage on previous eruptions of each of the volcanoes they looked at.

Fellow 6th form Bloggers,

 

I watched the second of the volcano live programmes and I found the second one explained to be very useful in explaining how pyroclastic flows actually happen. Gravity acts on the ash plume and forces it downwards. THis means that the the plume instead of rising, surges down the volcano at speeds over 100mph and at 1000 degrees centegrate....quite hot!

 

Personally I would have liked to see more footage of eruptions like there was in the fourth video, as i found it a lot more interesting.

 

 




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Volcano Live

After watching two episodes of Volcano Live, I can confidently say that my knowledge on volcanoes has definitely increased. Up to this school year, I've never put much thought into volcanoes. I always viewed them as nothing modern science couldn't handle. After watching volcano live I can see that I was horribly wrong. Not only are volcanoes still significant, if we didn't have the correct forms of management, we wouldn't stand a chance. I was amazed at how much devastation and destruction volcanoes caused in both the ancient and modern world. When Mt.Vesuvius erupted in 709 AD, the ash cloud covered the city of Pompeii and buried the people alive. On episode 4 of Volcano Live, this was one of the topics and I was shocked to see that people were still trapped & their bodies preserved in the exact position in which they died in. This I think shows the power of volcanoes and how they can have impacts and leave reminders of how significant they can be. This definitely my highlight of Volcano Live.

One thing which I would have liked to see covered in the program was the analysis of possible future eruptions. If volcanoes caused that much devastation to the past, I want to know what they could do in the future.



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Excellent Links on Nyiragongo

The 2 links below have been found to support research on Nyiragongo. They come with the Stroomer seal of approval and have been posted via email:

http://iugg-georisk.org/presentations/pdf/Wafula_volcano_Africa.pdf

http://www.photovolcanica.com/VolcanoInfo/Nyiragongo/Nyiragongo.html


Volcano Live

After watching 'Volcano Live' again I almost want to be a Volcanologist when I am older.

The way they erupt and the reasons behind them doing so are intriguing, but something which I noticed and picked up on and wasn't aware of is the management plans in place at some volcanoes. Its something which I think is overlooked somewhat, in EQ's management is very important and looked at but Mount Vesuvius surprised me:

The management strategy in place is extensive; In a two week period before the volcano will erupt 600,000 people in the Red Area (at danger to pyroclastic flows) will be evacuated through 16,000 army and policemen being mobilised and moving 80,000 a day through cars,bus,sea and other transport means. Then in Sakurajima, Japan, every Friday school children practice evacuation in case of an emergency; they use hard hats and gas masks as well as learning where to go e.t.c.

These management plans show there is real risk and people take it seriously, sometimes this can be overlooked by us not near.

I can't criticise the episodes, but, if I would have liked something extra it would have to be what goes on inside the earth and the mantle, looking at temperatures, movement and the like. But I can't fault the program, it was certainly up there with the best.

J.P.Strode