ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel
  • »
  • Education and Science»
  • Geology & Atmospheric Science

When The Earth Shakes

Updated on August 9, 2016
Seismic observatory.
Seismic observatory. | Source

Earthquakes Can Really Shake Your World

For some reason, earthquakes fascinate me. I've never experienced a quake larger than 5.3 on the Richter scale, and that was quite scary enough. Mostly, where I live, in Melbourne, Australia, we get tremors rather than earthquakes, so it's pretty safe.

One of my favourite countries, New Zealand, isn't so lucky, and suffers from them frequently, being on the "Pacific Ring of Fire", a very seismically active area.

Here, I'll explain a little about earthquakes, and what happens during one, mixed with my personal experiences.

The photo shows a seismological observatory in Japan.

Tectonic Plates.
Tectonic Plates. | Source

Tectonic plates sit on the aesthenosphere, which is the highest layer of Earth's mantle. All the plates move constantly, and where they interact, earthquakes and volcanoes often occur.

Tectonic plates are approximately 80 km thick, and move at anything up to 130 milimetres (13 cm) a year. This doesn't sound like much, but considering their size, there is tremendous pressure involved. When this pressure builds to a critical point, an earthquake or volcanic eruption takes place.

Earthquakes
Earthquakes

A book in the science series from the Smithsonian Institute- this is very factual.

 

A Few Facts

Chilean Earthquake 2010
Chilean Earthquake 2010 | Source

When two plates have been moving and a critical amount of stress has been reached, an earthquake occurs. Sometimes, there will be foreshocks, and it is impossible to tell if these are the main shock until the big quake happens. Often, a series of aftershocks occur after the big quake, and these can go on for months, or even years.

When a temblor (another word for earthquake) occurs, the site underground is called a hypocenter, and the area above ground is the epicenter. The strength of the temblor is measured by the Richter scale, which is open-ended. A quake of 6.4 is ten times as powerful in amplitude as one of 5.4 magnitude. The most powerful earthquake currently known was in 1960, in Chile, and was magnitude 9.4.

The image shows damage in Chile after the 2010 quake, an 8.8 on the Richter scale.

Little Quakes Can Be Scary

Seismograph of the Melbourne 5.3 temblor.
Seismograph of the Melbourne 5.3 temblor. | Source

In Melbourne, where I live, we are pretty much in the centre of the Australian tectonic plate, so we don't have major temblors. We have had a couple of small ones in the past few years, which have made the house tremble.

When I lived in Darwin, in the Northern Territory, there were a couple of minor quakes a couple of hundred kilometres away. in one, my sister and I were sitting reading, and the objects on the shelves started to vibrate, and the aquarium water sloshed a bit. We dashed out on to the balcony in case it got worse, but it only lasted a few seconds.

The strongest temblor I've felt in Melbourne happened in 2012, and was 5.3 on the Richter scale. It was the scariest, as I was alone in the house. I found out later that it was the largest in our state, Victoria, for 109 years.

I was sitting on the couch, reading, when all of a sudden, there was a huge bang, as if something had hit the house, and it started to shake. This went on for about 40 seconds, then slowly died away. Luckily, there was no damage, but it made me realise how terrifying a quake can be, and how fortunate we are to live in a relatively safe place.

The image is a seismograph of the earthquake.

Earthquake Poll

Have you been there when the earth shook?

See results

Liquefaction - Another effect causing damage

Liquefaction.
Liquefaction. | Source

Liquefaction sometimes happens during an earthquake, where the ground is not solid. If a building stands on sandy, or reclaimed land, and there is water in the sub-strata. during a quake the water rises, causing the ground to temporarily become liquid. This causes severe damage, as the foundations of building can move causing them to lean or collapse. Cars can sink into roads. Sometimes sand boils up a through cracks in the ground.

In some earthquake prone areas, after severe damage to suburbs, some places have been declared unsafe for buildings, and homes will be demolished, and the land returned to nature. This has happened in Christchurch, New Zealand, after the 2011 quake, where several suburbs were deemed to be too unsafe to rebuild.

New Zealand Suffers

Seismic Isolator.
Seismic Isolator. | Source

I've been to New Zealand a couple of times, and although it is known as the "Shaky Isles" I haven't felt any earth movement when I've been there.

On our first trip, we were in Auckland, and an earthquake was reported to have occurred that afternoon, not long after we landed at the airport. We didn't feel a thing. We worked out later that it could have been during the taxi ride, when we went over a bridge, and the car shuddered a bit - we thought it was just rough road, and the driver said nothing. I guess they are used to things like that in NZ!

When we were on the South Island, during our second trip, there was a medium sized earthquake during the night, while we were staying near the Fox Glacier. We both slept through that one, so it couldn't have been too bad where we were, or we would have been woken.

While I've been writing this, New Zealand has had another temblor, in Wellington, the capital. They had one there a few months ago too. Fortunately, this quake, at 6.5 magnitude, didn't cause any deaths, and only minor damage.

Many of the buildings in New Zealand are earthquake-proofed - they have strict building laws. When in Wellington, we visited the Museum of Te Papa (Te Papa is Maori for "Our Place"), and they have a section of their shock absorbers under the buildings open to the public. They are huge!

The image shows a seismic isolator, similar to those used in some buildings in New Zealand.

Catastrophes!: Earthquakes, Tsunamis, Tornadoes, and Other Earth-Shattering Disasters
Catastrophes!: Earthquakes, Tsunamis, Tornadoes, and Other Earth-Shattering Disasters

Disasters can come from many causes, but nature is the most powerful.

 

Your Earthshaking Experiences

    0 of 8192 characters used
    Post Comment

    • Snakesmum profile image
      Author

      Jean DAndrea 3 years ago from Victoria, Australia

      @TanoCalvenoa: So glad we don't have anything like that here in Melbourne, Australia. It isn't beyond the realms of possibility though! 5.3 is the biggest I've felt ever.

    • profile image

      TanoCalvenoa 3 years ago

      I was in a 7.3 quake that moved the road in waves in front of me, I've been in a 7.1 that shook the house really good and made a hanging lamp swing back and forth, and I've been in a 6.4 that rattled the windows hard and moved my bed six inches away from the wall early in the morning. These things happen every few years or so here in California.

    • Jim Houston profile image

      Jim Houston 3 years ago from Wilmer, Alabama

      We live along the New Madrid Fault line along the Mississippi River and there have been some tremors during my livetime but nothing severe. You never know how this will play out. They are having a ton of small 3.5 range swarms in Oklahoma now. Neat lens. JimHouston33

    • profile image

      MaryRoseFitz 3 years ago

      I work in Christchurch, New Zealand and experienced the 6.3 magnitude earthquake in February 2011. We had had 7.1 magnitude in September 2010 but there were no fatalities. They are scary to experience, the deafening roar and the rolling of the ground. But we can not control them and learn to live with them. Great lens

    • profile image

      MusicMentor 4 years ago

      This was an interesting lens. I only experienced an earthquake, a minor one, once a couple of years ago while at my job on Long Island, NY. I was sitting at my desk and felt some trembling under my feet. I didn't realize at first what was happening, but soon after discovered it was an earthquake.

    • socialcx1 profile image

      socialcx1 4 years ago

      I'm in New Zealand. Great lens

    • Snakesmum profile image
      Author

      Jean DAndrea 4 years ago from Victoria, Australia

      @mel-kav: I've been reading about them recently, and apparently there is nowhere completely safe from them; it's just that some areas have them far less frequently than others. Glad you were all ok.

    • mel-kav profile image

      mel-kav 4 years ago

      I live in Maryland, and we never get earthquakes. However, two years ago, we got one. I don't remember where it registered on the Richter Scale, it wasn't too big. But I will never forget that day and that feeling. My house was up for sale, and someone was coming to look at it in about 1/2 hour. After making sure everything was in order, I was on my way down the stairs to head out the door - exactly mid-way. That's when I felt the stairway violently swaying back and forth. I had lost all sense of balance and I felt disconnected from the ground. I had to brace myself by holding onto the stairway walls. There was a loud, terrible sound - like a freight train was coming through the windows. Things were falling off of shelves and furniture. I had never experienced an earthquake before, but I remember yelling to my daughter and my realtor, "What's happening?! I think we are having an earthquake?!" as I continued to brace myself with my hands against the walls. I don't think you are supposed to be in a stairwell during an earthquake, but we all survived. No real damage, just some things that fell to the floor.

    • smine27 profile image

      Shinichi Mine 4 years ago from Tokyo, Japan

      I live in Tokyo so we get them quite regularly. The largest one was the one two years ago.

    • SheGetsCreative profile image

      Angela F 4 years ago from Seattle, WA

      Living in So Cal during the 1980s-1990s gave me plenty of opportunities to experience some quakes!

    • TipsForMoms profile image

      TipsForMoms 4 years ago

      I was on the 60th floor of a department store in Tokyo when an earthquake hit. We didn't feel a thing! Their skyscrapers are really built to withstand shakes. Made me jittery just knowing, though.

    • FrancesWrites profile image

      FrancesWrites 4 years ago

      The Korrumburra quake in Melbourne rattled the steel carport which adjoins the brick wall of our house. It sounded as if a herd of cattle were running on top of it! We had some cracks appear in walls, and it wasn't until the 2012 quake that I could unplug the air conditioner from the powerpoint in one wall - it got fixed in by the Korrumburra quake!

    • katespetcorner1 profile image

      katespetcorner1 4 years ago

      Just a little wobble in England a while ago.