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EARTHQUAKES Monday 29/03 WEEK 9 – EARTHQUAKES DO NOW Read the section of text below. Some of the words have been spelt incorrectly. Identify the incorrect word and write the correct spelling for it: “An erthquake is the rapid movemant of the ground, usually back and fourth and up and down in a wave motion. It is caused by the rapid relese of energy as the tectonic plates move. The severety of an earthquake is calcalated in several different ways. There are some comonly used scales, such as the Richter scale and the Mercalli scale.” WEEK 9 – DO NOW ANSWERS Read the section of text below. Some of the words have been spelt incorrectly. Identify the incorrect word and write the correct spelling for it: “An earthquake is the rapid movement of the ground, usually back and forth and up and down in a wave motion. It is caused by the rapid release of energy as the tectonic plates move. The severity of an earthquake is calculated in several different ways. There are some commonly used scales, such as the Richter scale and the Mercalli scale.” Monday 29/03 WEEK 9 – EARTHQUAKES Lesson Aims: • Describe the causes of and methods of detecting earthquakes. • Recall different types of seismic waves and their movement through the earth • Differentiate between focus and epicentre. Homework: Education Perfect Tasks. CAUSES OF EARTHQUAKES AND DETECTION METHODS Detection Causes Rapid movement of the ground, usually back and forth and up and down. Caused by rapid release of energy as the tectonic plates move. Earthquakes are measured using a seismometer. The pen is fixed and the drum moves with the vibrations of the Earth. 3 TYPES OF SEISMIC WAVES Primary waves (P-waves): longitudinal (up and down) waves that travel fast through the Earth. Secondary waves (S-waves): transverse (back and forth) waves that travel slightly slower than P-waves through the Earth. Surface waves: are the slowest waves and cause the most destruction. WHERE EARTHQUAKES OCCUR Earthquakes occur under the ground where the Earth slips, usually along a fault. The quake starts at the focus, usually hundreds of kilometres deep in the Earth. The point on the Earth’s surface directly above the focus is called the epicentre.