EARTHQUAKES <ul><li>OBJECTIVES… </li></ul><ul><li>To be able to explain the location and cause of earthquakes. </li></ul><ul><li>To know the features of earthquakes – epicentre, focus, shockwaves and the measurement of earthquakes using the Richter and Mercalli scales </li></ul>Need world map Graph paper
<ul><li>An earthquake is a sudden movement in the earth’s crust. It is the sudden release of energy that causes seismic waves. </li></ul><ul><li>There are over 6000 earthquakes every year but most movements are too small for people to notice </li></ul><ul><li>Most earthquakes are caused by movement along a fault. They can occur anywhere, but they are most common and most serious along plate boundaries . </li></ul>
Seismograph The strength of an earthquake is measured using a seismograph.
How big? <ul><li>The strength of an earthquake is measured on the Richter scale . </li></ul><ul><li>If you go up 1 point on the scale it means the quake is 10 times bigger and about 30 times more energy is given out. </li></ul><ul><li>The amount of energy an earthquake gives out is called its magnitude </li></ul>
<ul><li>The point where the pressure is released is called the focus. </li></ul><ul><li>The point on the earth’s surface directly above the focus is the epicentre . </li></ul><ul><li>It is at or near the epicentre where most damage is done. As the waves spread out they decrease in strength </li></ul><ul><li>A fault is a crack in the earth’s crust along which rocks move. </li></ul>
Match the word with the definition: SEISMOLOGY SEISMOMETER EPICENTRE RICHTER SCALE TSUNAMI FOCUS 1. The place underground where the earthquake starts. 2. The centre of the earthquake where the effects will be greatest (directly above the focus) 3. A huge wave caused by an undersea earthquake. 4. A machine that measures the intensity of shaking during an earthquake. 5. A method of measuring the power of an earthquake. 6. The study of earthquakes.
7.4 3000 Turkey 1999 6.1 4000 Afghanistan 1998 7.2 5,477 Kobe, Japan 1995 6.6 57 Los Angeles 1994 6.5 10 000 Latur, India 1993 7.3 50 000 Iran 1990 7.1 67 San Francisco 1989 6.9 25 000 Armenia 1988 8.1 9 500 Mexico City 1985 7.6 240 000 Tangshan, China 1976 6.5 65 San Fernando USA 1971 7.8 66 000 Peru 1970 8.3 131 Alaska, USA 1964 7.9 156,000 Tokyo, Japan 1923 8.2 450 San Francisco 1906 RICHTER SCALE DEATHS PLACE YEAR
YOUR TASK….. On an outline map of the world – locate the earthquakes in the table. Note the year and the death toll Look at your map of plate boundaries. Describe the distribution of the earthquakes in relation to the types of plate boundary. Plot a scattergraph of the death toll for each earthquake shown in the table (y axis) against its strength (x axis). What is the relationship shown in the graph. How strong is the link between earthquake intensity and the number of deaths caused? 7.9 69,197 Sichuan, China 2008 7.6 19,000 Pakistan 2005 6.6 15,000 Bam 2003