ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

How Earthquakes Happen

Updated on October 5, 2018 (public domain worldwide image) (public domain worldwide image) | Source

An earthquake is the movement of the earth, which is a natural disaster and is often violent and devastating. An earthquake is usually caused by the sudden release of stress and pressure that may have gathered up over a very long period of time.

Waves of disturbance, or energetic waves known specifically as seismic waves, spread out from the origin of the focus, of the earthquake which is highly likely to be movement along a fault. Although and however, some earthquakes of the world are associated with activities from volcanoes.

In general, earthquakes are classified by their depth of focus which are:

1. Shallow - Earthquake between 0 to 70 kilometers (0-43miles) deep.

2. Intermediate - Earthquake between 70 to 300 kilometers (43-186miles) deep.

3. Deep - Earthquake between 300 to 700 kilometers (186-434miles) deep.

Over 75% of earthquake energy is concentrated in a belt around the Pacific Ocean and this is because most of the seismic activity occurs at margins of tectonic plates (see below for more information). This means that particular areas of the world are more probable to suffer from earthquakes. In other words, for example, the west coast of North and South America, Southeast Asia, Philippines, New Zealand and Japan are the most vulnerable to experience earthquakes.


The effects of earthquakes are naturally very disturbing, dangerous and fearful and also can be quite catastrophic. Near the focus, ground waves actually throw about the land surface. The surface effects may include the opening of large cracks (known as fissures), the breaking of roads and pipelines, bending and twisting of railway tracks and the falling down of bridges and buildings. Secondary effects, compared to surface effects, can be the same and very destructive if the vibrations of the ground initiate and trigger landslides, avalanches, tsunami or may cause large fires.

There are many systems of measuring the intensity of earthquakes. The common system in use is the Richter Scale which was created by an American seismologist and physicist Charles Francis Richter (1900-1985).

Table of the Richter Scale

Features Observed & Identified
This is detected by the use of seismographs
Sensitive people can notice this
Vibrations caused by large vehiccles when passing by
Light and loose objects are rocked and also felt by people walking
Rather Strong
People are awakened from this and also felt in general
Light and loose objects fall and trees also sway
Very Strong
Walls of buildings starts to crack
Buildings get some damaged and chimneys fall
Houses collapse, pipes break and ground starts to crack
Buildings destroyed, ground cracks badly and sometimes triggers landslides
Very Disastrous
Most buildings destroyed, bridges collapse and break, railways destroyed and landslides occur
The most violent destruction and the ground moves in wave (public domain worldwide image) (public domain worldwide image) | Source

This is a logarithmic scale, an amplitude of waves recorded by a seismograph, and because of this, the magnitude of one level is very much higher than the previous level. The principle study of earthquakes is called seismology, and so therefore in this field, seismographs are used to record the seismic waves (or shock waves as the waves of disturbance) as they spread out from the source. The seismograph has some means of conducting the ground vibrations through a device that transforms movement into a signal that can be recorded. The are several seismic stations around the world that record ground movements. Plus each one contains several seismographs with many seismometers which is the primary detector in connection with the seismograph.


Furthermore, at destructive plate boundaries one tectonic plate dips beneath the other at an oceanic trench in a process called subduction and in so doing old lithosphere is returned to the Earth's mantle. For example, island arcs are in connection with volcanic activity and associated with subduction at an ocean trench, where earthquakes are more often to occur.

When two continental plates converge, the continents collide to produce mountains such as the Alps, Pyrenees and Himalayas of today. The transform faults of conservative plate boundaries are produced by the relative motion of two tectonic plates alongside each other and one good example is the one in California known as the San Andreas fault. The San Andreas fault is the region which encounters earthquakes along a major fracture.

Tectonic Plates

Basically, tectonic plates are massive pieces of solid rock irregularly shaped and are of the Earth's crust and uppermost mantle. This is a general notion that brings together the variety of features and processes of the Earth's crust and is responsible for sea-floor spreading, continental drift, volcanic activity, earthquakes and the structure of the crust.

The coastlines on opposite sides of the world oceans seems to fit together, such as the Atlantic Ocean for example, and this has been acknowledged long time ago. With new discovery and evidence gathered, the crust and upper mantle of the Earth is scientifically named the lithosphere. This is believed to be consisted of seven large and over twelve smaller plates composed of continental crust or oceanic crust.

There are three types of plate boundary which are:

1. Constructive (Divergent) - This is relating to the ocean ridges where the two tectonic plates are moving apart. Such example of this occurrence is the plate in North America and Eurasia.

2. Destructive (Subduction Zones) - This is relating to the ocean trenches where plates are moving together, especially when an oceanic plate is forced under a continental plate. The Pacific and Eurasian plate is an example of this occurrence.

3. Conservative - This is relating to the transform faults where plates move and slide sideways past each other without a collision. The North American and Pacific plate is known for this type of activity.

4. Collision (Plate Margin) - This occurs when two continental plates moves towards each other, and the continental crust does not sink or nor destroy. Earthquakes are very common along these collision margins. One example is the Eurasian and Indo-Australian plate.


    0 of 8192 characters used
    Post Comment
    • DeBorrah K. Ogans profile image

      Elder DeBorrah K Ogans 

      8 years ago

      Aziza, WOW! Very educational! What an eye opner! I actually lived near the San Andreas fault. Voted Up! Thank You for sharing, Peace & Blessings!

    • Lady_E profile image


      8 years ago from London, UK

      Very interesting to read. I am more the wiser. Thanks.

    • Deborah Brooks profile image

      Deborah Brooks Langford 

      8 years ago from Brownsville,TX

      wow very interesting hub.. I was told I live on a earthquake fault.. over a 100 years ago there was an earthquake here.. it made the Mississippi River flow a different direction. plus we have tornadoes too.

      this is very educational. I will share this...

      great hub

      voted up



    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)