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Earthquakes, Tsunamis, Aftershocks, Whirlpools and Vortexes-Explanation of Earthquakes

Updated on May 23, 2013


  • earthquakes are caused by the movement of the earth’s tectonic plates (broken pieces of the earth’s crust)
  • tectonic plates are in constant motion, moving past each other, towards each other, and away from each other., and when they can’t pressure builds up, causing vibrations and tremors.
  • earthquakes occur without warning, and at anytime of the day or night
  • the Richter scale was developed in 1935 by Charles Richter to measure the energy released by the focus of an earthquake using seismograph
  • the Mercalli scale measures the physical effects of an earthquake by the Mercalli Intensity Rating of the Roman numerals I-XII. As an example Mercalli Intensity IV would be the equivalent feeling of a freight train passing through. A rating of X would show many structures and buildings collapsing.
  • the epicenter is the point above where the vibrations radiate in all directions, causing great destruction. The closer to the epicenter, the stronger the earthquake.
  • earthquake vibrations travel very fast and can reach the other end of the world within 20 minutes.

Electromagnetic Light Phenomena Before an Earthquake

  • there are hundreds of tiny earthquakes constantly going on underneath the earth that are never felt
  • faults are the boundary of any two plates.
  • magnitude is the energy the earthquake releases and measures the severity of the quake. A magnitude of 2.0 or lower is usually not even felt by people and called micro earthquakes
  • each year there are thousands of 4.5 and higher earthquakes around the globe and classified as moderate quakes
  • great earthquakes have a magnitude of 8.0 and greater. They are very powerful
  • for each unit of increased magnitude there is a 30 times increase in energy.
  • an 8.6 magnitude earthquake can release energy that equals 10,000 atomic bombs.
  • earthquakes can cause a volcanic eruption from a previously inactive volcano.
  • earthquakes can cause landslides
  • an electromagnetic light phenomenom occurs in the sky shortly before and sometimes during big earthquakes. Scientists are still studing the reason this occurs.
  • 80% of the earthquakes that have been recorded, take place in the Pacific Rim, New Guinea, New Zealand, Japan, South America, U.S.A., and Canada

The Earthquake in Japan

Epicenter of Earthquake in Japan 2011
Epicenter of Earthquake in Japan 2011 | Source

Japan's Earthquake Seen from Space

Earthquake along the coast of Japan 2011 as seen from space
Earthquake along the coast of Japan 2011 as seen from space | Source

What will someone experience with different earthquake magnitudes?

3.4 or less magnitude

Usually noticed by a few people near the epicentre.

3.5 - 4.2 magnitude

Felt by those indoors and some outdoors; vibrations similar to a passing truck.

4.3 - 4.8 magnitude

Many will feel this - windows rattle, dishes shake, cars standing still will rock.

4.9 - 5.4 magnitude

Everyone feels this shaking - everything moves dishes will fall and break and doors swing open, things will overturn

5.5 - 6.1 magnitude

Buildings may suffer damage - walls will cracks, bricks tumble, chimneys are damaged.

6.2 - 6.9 magnitude

Major building damage - houses can move from their foundations, major shaking causes furniture to move, chimneys will fall

7.0 - 7.3 magnitude

Serious damage to buildings - bridges swing and twist, walls break open, some buildings can collapse.

7.4 - 7.9 magnitude

Causes extensive damage - most buildings collapse.

greater than 8.0 magnitude

Devasting damage to the area - depending on how structures were built to withstand earthquakes, many will be reduce to rubble, tsunamis, landslides, volcanic eruptions and serious aftershocks will occur

See Earthquake Simulations From 4.0 to 9.0

Ariel View of Tsunami Damage

The tsunami and earthquake caused tremendous devastation to Japan
The tsunami and earthquake caused tremendous devastation to Japan | Source

Tsunamis and Earthquakes

Tsunamis are the effect of the tectonic plates colliding under the ocean.
A Tsunami occurs because the waves are traveling so fast and as the water reaches shallower land, the bottom of the water is slowing down, but the top of the wave is not. Now the top of the wave is higher than the bottom of the ocean forcing a wall of water on land.

  • tsunami is a Japanese word, translated means "harbor wave."
  • tsunamis are sometimes called tidal waves, but they are different because tsunamis are not related to the tides. A tidal wave will occur from a high tide occurring when there is a gravitational force from the moon, sun, and planets.
  • there are 3 phases to a tsunami: generation (sea surface reshapes from the earthquake), propagation (seismic energy is transported from earthquake source as deep waves form), runup (the most destructive phase as it comes ashore)
  • tsunamis can occasionally be triggered by a meteorite crashing into the sea, or from a major landslide, or from a volcanic eruption.
  • tsunamis are often generated from an earthquake
  • the force of energy from the earthquake at the floor of the ocean causes a series of waves that travel through the ocean.
  • tsunami waves travel over 500 miles per hour (800 kilometers/hour)
  • these waves are as high as the ocean is deep
  • as the tsunami gets closer to land, the shallow water makes the waves go up higher
  • as the ocean floor rises gradually, the wave becomes more powerful and can move miles inland, destroying everything that is in its path.
  • tsunamis are underwater earthquakes. When they happen in the middle of the ocean where the water is very deep, the waves may be a few feet higher, but when the waves get to land, they can be 200 feet high due to the shallow depths of water. The only place the water can go is up, as it nears land.
  • a Tsumani is made up of many waves known as a wave train.
  • the most destructive wave is not always from the first wave.
  • tsunami waves can be spaced as far as 1 hour apart and be as long as 100 kilometers or 60 miles long. They can cross a whole ocean without losing much energy.
  • tsunamis may not be noticed by those sailing on the ocean because the waves can be less than one foot high (30 centimeters) on the ocean surface in deep waters
  • the tsunami, once on land has such enormous energy, it destroys whatever is in its path, knocking demolishing buildings, washing away people, cars, homes, and even changing the coastline.
  • the tsunami is most similar to an extremely fast rising tide accompanied by violent underwater turbulence.
  • a tsunami has been described that it sounds like a freight train coming.
  • most tsunamis occur in the Pacific, but can occur in the Mediterranean and Caribbean Seas. Some have even occurred in the Atlantic and Indian Oceans
  • very often there will be a noticeable rise or fall in the level of the water. Water can recede from the shore as much as 5 minutes before the tsunami arrives.
  • tsunami waves can last for hours after the first wave, and the first of the waves may not be the most dangerous.
  • tsunamis can travel along rivers and streams as it gets to the ocean and can cause unpredictable water levels and dangerous currents in ports and harbors.
  • sensitive recorders have been put on the ocean floor to measure pressure changes in the water overhead, which sends the data to buoys in the ocean, which relay the information to satellites to help predict tsunamis.
  • 26 countries are part of TWS (The Pacific Tsunami Warning System) to monitor seismic activity for earthquakes that may trigger a tsunami.

Live Video of Tsunami in Japan

Waves Go Higher Than Houses

Measuring Foreshocks, Mainshocks, and Aftershocks

This chart shows the aftershocks from the earthquake over a year period.
This chart shows the aftershocks from the earthquake over a year period. | Source

Foreshocks, Mainshocks, and Aftershocks

When an earthquake occurs, there are foreshocks, the main shock, and aftershocks.
  • foreshocks are smaller earthquakes that come before the bigger quake. Not all main shocks have foreshocks.
  • aftershocks are earthquakes that are no further from the main shock than the length of the fault.
  • aftershocks occur in areas around the fault relieving stress
  • aftershocks occur in the same area as the main shock
  • by itself there is no way to differentiate between a main shock and a foreshock or an aftershock.
  • the main shock is always the earthquake with the highest magnitude
  • the aftershocks are unpredictable and random, but aftershocks follow a predictable declining pattern correlating with time, distance and magnitude
  • afteshocks can continue for months or even years after an earthquake has occurred.
  • the bigger the earthquake the larger the aftershocks
  • there are 3 mathematical calculations used to predict the size of the aftershocks
  • aftershocks can be as big as 1 less magnitude than the main shock
  • aftershocks can produce landslides, causing the weakened land to slip  and buildings can collapse that have already been damaged by the main shock.
  • time is an important factor with aftershocks - there are could be many aftershocks within the first hour of the earthquake and they decrease proportionately to the time since the main shock happened.
  • there are more smaller aftershocks than larger ones

Tsunami Travel Times

Travel time for the tsunami in Indonesia
Travel time for the tsunami in Indonesia | Source

Tsunamis Can Cause Whirlpools and Vortexes

Whirlpools and Vortexes in the Ocean

Whirlpool comes from a Dutch word that means whirling stream.

  • whirlpools are currents in the ocean that rotate in a circular directions and create rising and falling tides
  • after a tsunami the water drains quickly, like pulling the plug in a bathtub, as the waves recede the water spins and creates the whirlpool affect
  • a vortex can form when these rising and falling tides create a downward pull
  • most whirlpools are not very powerful
  • a powerful whirlpool is called a maelstrom
  • small whirlpools can be seen at the bottom of most waterfalls, Niagra Falls, being a large waterfall would have a strong whirlpool


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    • profile image


      4 years ago

      shpeak this even helps

    • profile image


      5 years ago

      I was in the 2004 Tsunami

    • toknowinfo profile imageAUTHOR


      5 years ago

      Hi JB, Thank you for stopping by. I am glad this helped with your school project. I hope you will refer to my other articles for other info you may need for reports. 6.9 earthquake is certainly scary. I am glad you made it through okay.

    • profile image

      JB Stewart 

      5 years ago

      Awesome info man, this really helped with a school project. I was also in a 6.9 earthquake on February 2012. It was scary.

    • toknowinfo profile imageAUTHOR


      5 years ago

      Hi Unvrso,

      Wow that must have been scary to experience such a powerful earthquake. I am glad you remained calm and were okay through it all. Thanks for the catching the typo. I appreciate you stopping by.

    • unvrso profile image

      Jose Juan Gutierrez 

      5 years ago from Mexico City

      very interesting! You provide useful information about earthquakes and tsunamis.

      I experienced a 7.9 magnitude earthquake on April 2012 in Mexico. I was in the middle of the street when the earthquake hit. I thought I was having a dizzy spell, but soon I realized it was an earthquake. I just stayed calm where I was until the ground movement stopped. There were aftershocks throughout the week.

      I think the word "tsumanis" must be "Tsunamis" in your title. Voted useful!

    • KaoriKumai profile image

      Nakashima KICO 

      6 years ago

      When I saw the Tsunami hit I felt really bad for all those poor Asian people who have gone to the after life! I feel bad for everyone there and it was reallt sad to see how many people got washed away and the whole Island just became a disaster.

    • profile image


      6 years ago

      im am a huge fan,i would love to know how u know so much about earthquakes,its so fab :P

    • profile image


      6 years ago

      please answer me with in the next 2 days

    • profile image


      6 years ago


    • profile image


      6 years ago

      what happened underground to cause the christchurch earthquake?????????????????????

    • profile image


      6 years ago

      why do aftershocks never occur in the same place


    • toknowinfo profile imageAUTHOR


      7 years ago

      Hi Susan, Thanks for stopping by and reading. I am glad you found this hub informative. I appreciate your up ratings.

    • Susan D Tyndall profile image

      Dianne Tyndall 

      7 years ago from Sanderson, Texas

      Excellent hub great video's and information, voted up and useful.

    • justmesuzanne profile image


      7 years ago from Texas

      Lots of very impressive research and good information! Rated up & useful! :)

    • toknowinfo profile imageAUTHOR


      7 years ago

      Nature is so powerful. It shows how quickly our lives can change.

    • Micky Dee profile image

      Micky Dee 

      7 years ago

      Lot of work toknowinfo. We continue to shake our heads at world events. God bless you dear.

    • Twilight Lawns profile image

      Twilight Lawns 

      7 years ago from Norbury-sur-Mer, Surrey, England. U.K.

      Thank you for an incredibly well organised hub. A terrifying and frightening subject; an awesome ub.

    • Betty Johansen profile image

      Betty Johansen 

      7 years ago

      Fascinating and terrifying!

    • einron profile image


      7 years ago from Toronto, Ontario, CANADA

      Very informative and excellent hub.

      I have written a hub on THREE DIFFERENT DISASTERS 2 years ago.

      This is foretold in the Bible before the return of Jesus Christ. May God have mercy on the people.

    • Fossillady profile image


      7 years ago from Saugatuck Michigan

      Incredible footage and thorough information!!

    • vietnamvet68 profile image


      7 years ago from New York State

      very well put together hub and very informative. I can tell that you have done your homework on this piece. Thanks for sharing

      God Bless

    • toknowinfo profile imageAUTHOR


      7 years ago

      With the events that are going on in Japan, I needed to make sense of it all. Science can help us learn a little, but it is still hard to comprehend. I hope this helps us all understand in a better way what has happened. My prayers are with the people of Japan and all their loved ones around the world who worry for their safety.

    • Tamarajo profile image


      7 years ago

      Very interesting article. I liked the listed effects of the different sized quakes. I have always wondered what that was like and the video was helpful with that

      I also didn't know about the tsunami waves that aren't just one big wave but several and the first one not always being the biggest one.

      And interesting about aftershocks. I always wondered how would they know if something was an aftershock or a new quake.

    • profile image


      7 years ago

      great useful hub i was totally unaware..!!! thanks

    • kashmir56 profile image

      Thomas Silvia 

      7 years ago from Massachusetts

      Hi toknowinfo, Great information and very well explained about the mega force of a massive earthquake .

      Awesome and vote up !!!

    • breakfastpop profile image


      7 years ago

      Thank you for providing an explanation of this disaster.Voted up and useful.

    • RevLady profile image


      7 years ago from Lantana, Florida

      Excellent and informative. I learned a lot. Thanks so much. Voted up, useful and facebooked it!

      Forever His

    • profile image


      7 years ago

      Thanks for your detailed educational hub. You have summerized the events and they should be remembered by us for the future. My heart and prayers go out to the Japanese people. It is unbelievable to see the damage and how it happened. I now wonder about the ships in the oceans and their safely.

    • cupid51 profile image


      7 years ago from INDIA

      I got extensive knowledge update from this hub! Thanks for sharing it at this time when the entire population of the world are in shock!

    • jojokaya profile image


      7 years ago from USA

      Excellent hubs..

    • profile image

      Fay Paxton 

      7 years ago

      Thank you for this excellent and informative hub. I watched the videos...scary.


    • toknowinfo profile imageAUTHOR


      7 years ago

      Hi Drbj, Nature is very powerful and I find it humbling to see all it can do. My butterfly hub shows the beauty of nature and this hub shows the destructive force of nature. Like you said, it is unbelievable.

    • drbj profile image

      drbj and sherry 

      7 years ago from south Florida

      Excellent descriptions, tki, of this menacing force of nature and the videos are unbelievably frightening. To see the large boats tossed about like splinters and large buildings simply dissolving is absolutely unbelievable.


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