Natural DIsasters – for 4KM and 4KJ – Volcanoes, Earthquakes and Tsunamis

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.

7 thoughts on “Natural DIsasters – for 4KM and 4KJ – Volcanoes, Earthquakes and Tsunamis

  1. Georgia (4KM and 4KJ)

    Dear Ross Mannell,

    What an extremely long comment for 4KM and 4KJ! Thank you very very much.

    On our class blog, you wrote (typed) Georgia – Your swan Tagxedo was swimmingly good. Thats me! Thank you for the funny comment.

    Bye for now,

    Georgia (4KM)
    😀 :mrgreen: 😳

    Reply
    1. rossmannell

      Post author

      Dear Georgia,

      Thanks for your comment. All of your class’s Tagxedos look very creative and packed with great words.

      The post did take some time but I am interested in geology as well as many other things. I’ve been in the crater of New Zealand’s Mt Tarawera volcano and on the slopes Mt Ruapehu and Mt Tongariro also in New Zealand. I’ve walked the lava fields in Hawaii and been in a helicopter so I could see the flowing lava in a caldera (crater). Vulcanology (the study of volcanoes) has been a hobby of mine. We have a fascinating world if we keep our eyes and minds open. 🙂

      @RossMannell

      Reply
      1. Georgia (4KM and 4KJ)

        Dear Ross Mannell,

        Wow! You have been in a crater before. I have never been near or really close to lava before.

        I have not been to New Zealand but my Dad is thinking of going on a holiday there. Those islands have funny names for them. Do you know why there called that?

        I think a study of volcanos are very interesting. We do have a very interesting world and I can’t wait to grow up and discover more.

        Your Blogging Buddy,

        Georgia (4KM)

        😀 😳 :mrgreen:

        Reply
        1. rossmannell

          Post author

          Thank you for your comment, Georgia.

          Near Rotorua in New Zealand’s North Island, you will find Mount Tarawera. During the early hours of 10 June, 1886, Mount Tarawera erupted with a massive explosion. You can see some information about the eruption and the once beautiful Pink and White Terraces…
          http://www.nzhistory.net.nz/eruption-of-mt-tarawera

          There are tours run from Rotorua. You go by four wheel drive up to the rim of the crater. Guides take you along the rim and then down into the crater. It can be scary for those afraid of heights but I went along with a tripod and camera and had great fun having the experience.

          Is Mt Tarawera still active? The volcano is dormant (sleeping). One day pressure may again build up from underneath and cause another eruption. Volcanoes can be like that, dormant for a long time until the pressures from below become too high and release in an eruption.

          Strange names? Many place names in New Zealand come from the Maori people. The Maoris are part of the Polynesian cultures found on many Pacific Ocean islands. Their culture is very interesting and their place names tell you about the place. Here is one place name for a hill…
          Taumatawhakatangihangakoauauotamateapokaiwhenuakitanatahu
          Yes, it’s one word. Wikipedia tells me it roughly means…
          The summit where Tamatea, the man with the big knees, the climber of mountains, the land-swallower who travelled about, played his nose flute to his loved one.

          How’s that for a name? 🙂

          Reply
  2. Lilli (4KM)

    Dear Ross Mannell,

    WOW, you must have gone to a lot of effort to make this comment/blog post! 🙂

    I think the idea of an extended comment blog is a great idea! 🙂

    From Lilli =)

    Reply
    1. rossmannell

      Post author

      Thanks for the comment, Lilli.

      As you probably know, I comment on many blogs. Every now and then, a blog post sparks an interest in me. This can happen when an interest of mine is mentioned. While the post did take some effort, it was interesting to put it together and share a little of my interest in volcanoes. 🙂

      Reply

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