R+-+Earthquakes

__**The distribution of Earthquakes**__

Earthquakes are located on plate boundaries as shown by the grey shaded areas on the diagram above.

__**Causes of Earthquakes**__

An earthquake is caused when two plate tectonic plates push together or try to slide against each other. As the plates move **friction** stops the plates from moving past each other. This leads to a build up of **pressure**. Eventually the pressure gets too much and the plates move which causes an earthquake.



__**Key terminology**__

· **Magnitude ** – how strong an earthquake is ·  **Richter scale ** – the scale on which the strength of the earthquake is measured · **Focus ** – the place deep in the earth where the rocks are moving · **After-shock ** – smaller earthquakes after the main, large one · **Seismometer ** – an instrument to measure the strength of the earthquake <span style="font-size: 12pt; font-family: Symbol; mso-fareast-font-family: Symbol; mso-fareast-language: EN-GB; mso-bidi-font-family: Symbol; msofareastfontfamily: Symbol; msofareastlanguage: EN-GB; msobidifontfamily: Symbol; msolist: Ignore;">· **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Epicentre **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;"> – the point at the surface above the focus <span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: 'Times New Roman'; mso-fareast-language: EN-GB;"> __**Primary and Secondary Effects**__ <span style="font-size: 12pt; font-family: Symbol; mso-fareast-font-family: Symbol; mso-fareast-language: EN-GB; mso-bidi-font-family: Symbol; mso-font-kerning: 12.0pt; msofareastfontfamily: Symbol; msofareastlanguage: EN-GB; msobidifontfamily: Symbol; msolist: Ignore; msofontkerning: 12.0pt;">· **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Primary effect **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;"> – are the immediate damage caused by the quake, such as collapsing buildings, roads and bridges, which may kill people. <span style="font-size: 12pt; font-family: Symbol; mso-fareast-font-family: Symbol; mso-fareast-language: EN-GB; mso-bidi-font-family: Symbol; mso-font-kerning: 12.0pt; msofareastfontfamily: Symbol; msofareastlanguage: EN-GB; msobidifontfamily: Symbol; msolist: Ignore; msofontkerning: 12.0pt;">· **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Secondary effect **<span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;"> – the after-effects of the earthquake <span style="font-size: 12pt; font-family: 'Courier New'; mso-fareast-font-family: 'Courier New'; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt; msofareastfontfamily: 'Courier New'; msofareastlanguage: EN-GB; msolist: Ignore; msofontkerning: 12.0pt;">o <span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Fires <span style="font-size: 12pt; font-family: 'Courier New'; mso-fareast-font-family: 'Courier New'; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt; msofareastfontfamily: 'Courier New'; msofareastlanguage: EN-GB; msolist: Ignore; msofontkerning: 12.0pt;">o <span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Tsunami <span style="font-size: 12pt; font-family: 'Courier New'; mso-fareast-font-family: 'Courier New'; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt; msofareastfontfamily: 'Courier New'; msofareastlanguage: EN-GB; msolist: Ignore; msofontkerning: 12.0pt;">o <span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Landslides <span style="font-size: 12pt; font-family: 'Courier New'; mso-fareast-font-family: 'Courier New'; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt; msofareastfontfamily: 'Courier New'; msofareastlanguage: EN-GB; msolist: Ignore; msofontkerning: 12.0pt;">o <span style="font-size: 12pt; font-family: 'Times New Roman','serif'; mso-fareast-font-family: +mn-ea; mso-fareast-language: EN-GB; mso-font-kerning: 12.0pt;">Disease and famine