Volcanoes & Earthquakes

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To see 4KM and 4KJ’s original post….

Natural Disaster Tagxedos

REMEMBER: I am not an expert and have to check much of the information below.  If I find any errors, I will correct them as needed.

Dear 4KM and 4KJ,

 Natural disasters are part of living on an active planet with an atmosphere.

What do I know about natural disasters?

Volcanoes, earthquakes, tsunamis and our  not so solid world…

Most of you know our world isn’t a solid ball. Here is a graphic showing the Earth's internal layers I prepared for you...

Schools and students have permission to use this graphic for non-commercial, educational purposes.

The INNER and OUTER CORE

At its centre, the INNER CORE, it’s thought to be a solid iron-nickel core. The temperature is thought to be about the same as the surface of our sun.

Now, that’s very hot so should the iron-nickel inner core melt? It is solid because of pressure from the rest of the earth not allowing it to melt.

The OUTER CORE surrounds the INNER CORE.  It is liquid and very hot. It’s thought, like the INNER CORE, to be mostly iron. It’s thought to be very important to life on Earth. Movement of the liquid iron OUTER CORE causes Earth to have a magnetic field (like a magnet with a north and south pole). It’s this magnetic field which protects us from much of the sun’s solar wind (ionised gases). If it wasn’t there, we wouldn’t ne able to live on Earth’s surface without protective suits. With the core of Mars thought to be cold, Mars has little magnetic field and certainly not a whole planet one. We would need suits to protect us even though it is further from the sun than us.

 

Schools and students have permission to use this graphic for non-commercial, educational purposes.

EXPERIMENT: Place a magnet underneath a piece of paper. Sprinkle on some iron filings. You will see the iron filings

The MANTLE

The MANTLE is the thickest layer in the Earth. It is solid but is at high temperature so there is movement over long periods of time as cooler material sinks and hotter material rises. You might already know about convection. You know hot air rises because it is lighter and cooler air falls because it is heavier. It’s the same with the rocks in the MANTLE.

OBSERVATION: Have you ever seen a lava lamp? As the wax in the lamp heats, it rises to the top of the lamp. When it cools it falls back down only to be heated and rise again. That is convection.

More about convection shortly.

The CRUST

This is the thin layer we live on. Think of an apple. It has a core, the delicious fleshy part  (like Earth’s MANTLE), and the skin (the CRUST). Like an apple, the Earth’s crust is thin and sits on the MANTLE.

OBSERVATION: Cut an apple in half and look at the cut surface. Imagine it’s the Earth. We live on the thin skin.

The convection (movement) in the MANTLE causes movement in the crust. The Earth’s crust has large sections called TECTONIC PLATES.

You can see a map of the Earth’s plates on Wikipedia at

http://en.wikipedia.org/wiki/File:Plates_tect2_en.svg

The TECTONIC plates rub along each other, go over or under each other, or move apart. Now for natural disasters…

VOLCANOES

Most volcanoes in the world are found along the edges of the TECTONIC PLATES. Some, like the Hawaiian volcanoes, are over a HOT SPOT. Volcanoes are places where heat and pressure from the MANTLE can be released. There are many types of volcanoes. In Hawaii, you have lava flows whereas New Zealand’s volcanoes tend to be more ash and gases. No matter what type, eruptions can be very dangerous for people living close to volcanoes.

Here is a link to a post I made some time back for a class in England. It shows some You Tube volcanic activity…

http://rossmannellcomments.edublogs.org/2012/05/23/a-final-volcano-post-of-you-tube-links/

Here is another link to a post I made for the same class. It includes some video clips I made while in New Zealand.

http://rossmannellcomments.edublogs.org/2012/05/23/new-zealand/

In many areas of Australia, you can find the remains of volcanoes once very active millions of years ago. If you know what you’re looking for, they are easy to spot. Where I live, there are plenty of signs of ancient volcanic activity. Here is a photo of an easy to spot one in Queensland. It shows the solidified magma once in a volcano's crater....

Schools and students have permission to use this graphic for non-commercial, educational purposes.

EARTHQUAKES

When the TECTONIC PLATES try to move, pressure can build up as they rub against each other. This can happen at the edges of the plates or along fault lines. Eventually, the pressure is too high and the plates or rocks in the fault move. This is an earthquake.

Here is a Wikipedia link to a photo of the San Andres fault in California…

http://en.wikipedia.org/wiki/File:Falla_de_San_Andr%C3%A9s.jpg

and to a graphic of the types of faults…

http://en.wikipedia.org/wiki/File:Fault_types.png

When there is tectonic movement, land can move up, down or sideways. Some quakes are small tremors where there is shaking but they can be large and cause much damage. Do you remember hearing about the earthquakes and aftershocks in Canterbury, New Zealand?

Look at the photo below. I took it at a roadside cutting near my town. See how the rock had been forced into curves by pressure. Have you seen layers of rock in unusual patterns? Do you think earthquakes or earth movements might have been the cause?

Schools and students have permission to use this graphic for non-commercial, educational purposes.

EXPERIMENT: Place piece of cardboard on your desk. Now place a stone near the edge of a piece of cardboard. Lift the edge of the cardboard. For a time, friction will hold the rock in place but as you keep raising the edge of the cardboard and the angle increases, the stone will start to slip. For the rock, it was like a mini earthquake when it moved.

TSUNAMI

You might have heard about powerful waves called tsunamis. When you go to the beach and watch the waves, these are only surface waves. The water simply moves up and down close to the surface and is caused by the action of wind. If you’ve ever seen a fishing float in the water if you’ve gone fishing, you’ll see it moving up and down. It will only move along sideways if there is wind to blow it or flowing water underneath.

Tsunamis are very different to the normal waves you see. They are much deeper waves and can be caused by underwater earthquakes, volcanic eruptions, landslides or other disturbances including a meteorite impact in the ocean. When an event occurs, huge amounts of water is displaced (moved).

If you were out on the ocean, you mightn’t even notice a tsunami pass as it might look like any other wave but it goes much deeper than a normal wave. As a tsunami approaches shallower water, the deeper waves rise up and move in on the coast.

In 2004, there was an underwater earthquake near the island of Sumatra in Indonesia. A large amount of water was displaced and spread out across the Indian Ocean. With Sumatra being so close to the earthquake location, large waves washed ashore causing a huge amount of damage to the town of Banda Aceh.  The more distant from the site of the earthquake, the less the effect,

Here is a Wikipedia link to an aerial photo of Banda Aceh taken after the tsunami.

http://en.wikipedia.org/wiki/File:US_Navy_050102-N-9593M-031_A_village_near_the_coast_of_Sumatra_lays_in_ruin_after_the_Tsunami_that_struck_South_East_Asia.jpg

OBSERVATION 1: Have you ever dropped a large rock into a still pool and seen water splash up and waves ripple out? This gives you the idea the way waves spread out from the point of origin.

OBSERVATION 2: When you fill your bathtub to the top then get in, what happens? This is water displacement as your body moves water away as you get in.

WOULD IT BE BETTER NOT TO HAVE SUCH AN ACTIVE EARTH?

If you remember, I’ve already explained our active, hot Earth protects us from much of the effects of the sun. If our Earth’s interior cooled and went solid, we might not have problems with earthquakes and volcanoes but we would be exposed to dangers from the sun. Earth might become more like Mars.

I think we are fortunate to have an active Earth even if it sometimes causes natural disasters.

If you are interested to find out more about natural disasters, The Australian Government Geoscience Australia website has information on (CLICK TO GO TO THE SITE)…

You can also check Wikipedia for information.

I had intended adding video of my helicopter ride over Hawaii. It showed lava flowing into the ocean as well as a view into a caldera at the lava below. Having had my trasnfer device break down, I though I would add some You Tube links of volcanic activity if it's okay for you all to view....

National Geographic also has a short video of their favourite photos of volcanic activity. There is an ad at the beginning.

I hope you all have had fun learning about volcanoes.

 

 

Just a reminder, I am not a volcanologist just a geology hobbiest. I try to get my information correct but you can let me know if you find any errors. 🙂

In the last post, I looked at hot spots. New Zealand's active thermal areas are different to Hawaii. New Zealand lies on the fault line caused by the interaction of the Australian and Pacific plates.

Wikipedia has information on plate tectonics

http://en.wikipedia.org/wiki/Plate_tectonics

Look at the image below from Google Earth or find New Zealand if you have now installed Google Earth. You can see the fault line to the south-west of New Zealand (bottom left corner). It runs across the South Island of New Zealand then off to the north-east.

Tension can build up as the plates move. When the tension is suddenly released, you get earthquakes. Near fault lines, you can find volcanoes and thermal areas such as in the North Island of New Zealand.

Below is an old image of Mt Ngauruhoe erupting well before you were all born. I think it was in the early 70s but I don't remember when. Mt Ngauruhoe is what I would call a classic volcanic cone shape and is really a part of the Mt Tongariro volcanic complex.

http://en.wikipedia.org/wiki/Ngauruhoe

Mt Ngauruhoe is to be found in the Mt Tongariro National Park on the North Island of New Zealand. Mt Tongariro is volcanic complex including Mt Ngauruhoe. Below is a Google Earth image of the national park.

http://en.wikipedia.org/wiki/Mount_Tongariro

In 1995, I had been in Invercargill at the south end of New Zealand's South Island when I heard Mt Ruapehu (in the Tongariro National Park) was erupting. I wasn't able to book a flight north for a few days because of the dangers the erupting volcanic ash posed for planes. I caught one of the first flights north and went to pick up a rental car. I had to dust off the volcanic ash which had settled on the car before heading to the volcano.

On arriving at the national park, I wasn't able to travel too close but was on the lower slopes. It had settled down and was smoking constantly. I took some photos and video clips before leaving. Two days later I heard one person had managed to sneak through the police lines so he could stand on the rim of the volcano to watch the smoking crater. On arriving back down, the man was arrested. Later that day the volcano again became very active. An explosion destroyed the ledge the man had been on. Volcanoes are very dangerous when they are erupting. I always keep my distance when the warnings are out.

Below are two video clips I took on the day. The first is the original footage taken some kilometres from the volcano. The second has been accelerated to show the escaping smoke and ash.

PLEASE NOTE: The video clips in this post were taken when home video cameras were reasonably new. The quality is poor due to the early camera and the low quality Quicktime movies made back then.

This 2nd clip is only a few frames long. Once loaded keep clicking on play to see the movement not easy to see in the first video above. From a distance you can't always see much happening.

 

 

Rotorua and Its Thermal Sites

One of the most popular ares of the North Island of New Zealand is Rotorua. There are numerous thermal areas to visit as well as the nearby Mt Tarawera I mentioned in an earlier post. Here are a few photos.

Pohutu Geyser photos, Whakarewarewa

 

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

 

 

A video clip of the Lady Knox Geyser near Rotorua

Schools and students have permission to use this video clip for non-commercial, educational purposes.

Hot Mud Pools, Whakarewarewa

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

A video clip of the boiling mud

Schools and students have permission to use this video clip for non-commercial, educational purposes.

Thermal Water Pools (hot enough to boil an egg), Whakarewarewa

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Boiling Water Pool (Orakei Korako south of Rotorua)

Schools and students have permission to use this video clip for non-commercial, educational purposes.

Whakarewarewa is a major tourist attraction in Rotorua. It is owned and run by the Maori people. As well as the thermal areas, there is a cultural centre where students learn the art of wood carving. Here are two carvings in my collection.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

For a Wiki link to Whakarewarewa http://en.wikipedia.org/wiki/Whakarewarewa

Te Wairoa

The Buried village of Te Wairoa is near Rotorua. It lies to the west of Mt Tarawera near the shores of Lake Tarawera. You might remember I mentioned the 1886 eruption that made the scree sample I sent you.

The village was traditional Maori. On the morning of June 10, 1886, the people of the village were woken by the eruptiing Mt Tarawera. Ash and rock was thrown up into the air by the massive explosion. As the ash fell back to earth, the nearby village was covered. 120 people lost their lives in the eruption, many of them from this village. Below is one of the unearthed structures. Archeologists have uncovered a number of the structures of the village.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

The picture below is a scan of a coloured slide I took a number of years ago. The quality isn't brilliant but it wlll hekp me give you a little more information.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

The east coast of the island of Oahu, Hawaii gives you an idea of how rugged volcanic coasts can be. Many locations in Hawaii have been used in movies and television shows. "Lost" and "Jurassic Park", for example, made use of Hawaii's rugged and beautiful locations.

The Hawaiian islands are located over what is known as a hotspot*. Over millions of years, the movement of the crust has caused volcanoes to appear in a chain. Look at the Google Earth image below. Stretching away to the north-west, you can see the chain of submerged islands that may once have been above the water. Google Earth allows you to see these. It's a great way of looking for geological features on a large scale. Have you already loaded it so you can zoom in?

The hotspot is still very active. A large new volcano is already growing beneath the ocean to the south of Hawaii and will most likely one day be seen above the ocean surface. We have a very active world beneath us.

Link for hotspot:

http://en.wikipedia.org/wiki/Hotspot_%28geology%29

Want Google Earth... go to:

http://www.google.com/earth/index.html

 

Hello Year 6,

This post is to give a little information about the last two of six samples you should soon have.

Iron Sands

The small iron sand sample I've sent came from a riverside beach on the North Island of New Zealand at a place called Awakino. You can use Google Earth to locate the river mouth in the photo below.

Iron sands (or titanomagnetite) were eroded from volcanic rocks and washed down rivers. The sands can vary in iron content but at Awakino are 95+% iron. The sand is very easily picked up by magnets but is hard to get all of it off again so if you try to pick the sand up with a magnet, wrap the magnet in paper to make it easy.

Iron sands are mined in places because of their high iron content. The site below gives some more information...

http://www.ttrl.co.nz/cms.aspx?page=What_are_Iron_Sands&flag=1

The picture below has been scanned from a slide taken over 25 years ago on one of my trips to see New Zealand's sights and especially the volcanic areas of the North Island.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pumice Stone

Pumice is a 'frothy' lava formed when super-heated lava under high pressure mixes with water such as in underwater volcanic eruptions. When the lava is released, the sudden change in pressure and rapid cooling form gases in the cooling rock. The pumice stone is very light and can float on water.

I think the pumice stone I have sent you came from an underwater eruption near Tonga in about 1984. Huge rafts of the pumice floated towards Fiji, some even making it to the shores of Australia where I found the sample on a beach.

For more information on pumice, the Wikipedia link below may help

http://en.wikipedia.org/wiki/Pumice

Remember you can check out Tonga and Fiji using Google Earth. The image below shows Fiji and Tonga. You can see Tonga is really the tops of peaks in an underwater mountain range. You can use Google Earth to view other areas. Try places such as Hawaii's Big Island, Yellowstone National Park in USA, Mount Etna, Mount Vesuvius, Iceland, Mount Kilamanjaro and any other volcanoes or thermal areas of interest. Google Earth can almost take you inside.

 

In this post, I'm going to show you some photos taken of an active volcanic area on The Big Island of Hawaii. The island is the real Hawaii but, as most people think of all the isalnds as Hawaii, they tend to call it The Big Island.

Here is a link to information about The Big Island...

http://www.gohawaii.com/big-island/regions-neighborhoods/kau/hawaii-volcanoes...

The photos below were taken of lava flows on Kilauea, one of the world's most active volcanoes. Tourists aren't allowed to get too close to lava flows because of the danger so these came care of a friend. I will later post some taken by me from the safety of a helicopter above a caldera*.

* http://en.wikipedia.org/wiki/Caldera

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These photos show pahoehoe lava flows. Being cooler, the darker colour flows ooze out of the lava tubes like honey from a tipped jar.

 

The following two photos were taken from a helicopter. As the flowing lava hits the sea water, clouds of steam are formed as the water boils. The constant flow of lava adds to The Big Island.

Below is a Google Earth image of Hawaii. If you download Google Earth to your computer you can zoom in on Mauna Loa, Mauna Kea and Kilauea volcanoes.

Hello Year 6,

The small samples of scree and obsidian are from New Zealand's volcanic areas on the North Island.

I am not sure exactly where the obsidian came from but I know it can be found in the crater although people aren't permitted to collect it there. I have seen samples in the crater. The piece I have and the small sample I've sent were bought at a rock shop.

The scree sample is from the crater and is an accidental collection example. When in Rotorua, New Zealand, you can book to go on a tour of the crater. You are driven up to the crater edge by 4WD cars before hiking up along the crater rim then  making a steep descent through scree to the bottom of the crater.

When I say a quick descent, you follow a steep track over the crater rim then make large strides in the scree. Each step seems to be over a metre in length as you move along.Care has to be taken as it is a long way to roll to the bottom if you fall.

On arriving back after the trip, I found many bits of scree had been caught in clothing and boots. They became my collection of scree.

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Obsidian - volcanic glass -

http://en.wikipedia.org/wiki/Obsidian

Scree - or talus, is broken rock fragments. The scree in the crater was made when the Mt Tarawera erupted in 1886 -

http://en.wikipedia.org/wiki/Scree

Mt Tarawera, New Zealand -

http://en.wikipedia.org/wiki/Mount_Tarawera

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A great way to view volcanoes is to use Google Earth. The satellite images can let you look down craters.

Here is a link to Google Earth. You would need to download it.

http://www.google.com/earth/index.html

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Image 1: A screen capture of Google Earth viewing Mt Tarawera, New Zealand.

If you load the full sized image, you can see a rectangle drawn on the screen shot of Mt Tarawera. The rectangle roughly shows you where the next photo shows, inside the crater.

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Image 2: A photo I took when I was on a tour into the crater of Mt Tarawera. I was standing on the eastern rim of the crater and was looking west. The arrow points to a group of people on the far side. They are about to make their way into the crater. Their size can give you an idea of how large that part of the crater really is. You can make out the track. It's quite an experience.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

I have organised a few family trips to New Zealand for families in schools where I've taught. The thermal areas and volcanoes are wonderful.When I took this photo, I had some students with me. They were worried the volcano might erupt while we were in it. At that time, the volcano had erupted just over 110 years before.

I smiled and said, "It erupts about every 110 years so we're safe.... Wait a minute, it's due now."

The boys I was talking to knew me well, "Sure," they said with a smile.

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Hello Year 6, High Lawn.

I have a package ready to send to you on the next mail. It should arrive by the end of next week (September 30) if all goes well. The package contains six small samples I've collected over a number of years.

This initial post on this blog is to let you know a little about what is arriving. I will make more posts with greater details as I get time. At first, the posts will let you know what each sample is, how and where I collected it and a little bit about the place I collected it.

Later posts will include photos and video clips I've taken in and around volcanic areas in New Zealand and Hawaii (the Big Island). I'll also try to add links to sites or video clips that may be of use or show what I am posting.

I hope you like the samples. The photos were taken on a grid where each square is 1cm by 1cm so you can see the sizes.

 

Scree from New Zealand. I collected this almost accidentally while making my way down to the bottom of a volcano crater.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Obsidian or volcanic glass. Again, this sample is from New Zealand. It also came from a volcanic crater although this was part of a piece I had bought.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Iron sands. I collected this from a beach on the North Island of New Zealand. there, the beach is black with sand almost 100% pure iron. It can be picked up by a magnet. Despite being iron and in salty water, it doesn't rust and is much better to use than iron filings when playing with magnets.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pumice. This is a very light rock which, if I remember correctly, came from a volcano under the ocean near Fiji. Large amounts in the underwater eruption floated to Australia. I collected this from a beach. A number os on the back of it. This was just a spare numbered sample from my collection.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

Pahoehoe is one of the types of lava from an Hawaiian volcano. Once cooled, it is the easiest to walk on. It breaks down into black sand.

Schools and students have permission to use this graphic for non-commercial, educational purposes.

'a'a is the second type of lava coming from hawaii. It tends to have sharper edges and is harder than pahoehoe. I like to think it's named that because of the sound you make if you walk on it barefoot when it is cooled.

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I hope you like your little collection from the other side of the world. My home town here was once a volcanic region but this was many millions of years ago. I see many traces it was once active but the above samples are much more recent and from active volcanoes. More on this later.

Ross Mannell (teacher)

Australia