BUILDING HIGHER LAND MANAGEMENT 13 Read the passage and decide if the statements below are true or false. Then correct the false ones. EARTHQUAKES In an earthquake, huge masses of rock move beneath the Earth s surface and cause the ground to shake. Earthquakes occur constantly around the world. Often they are too small for people to feel at all. Sometimes, however, earthquakes cause great damage. Most earthquakes are caused by changes in the Earth s crust. The crust is made up of about a dozen rock masses called plates that are constantly moving. In different places, they move apart, collide, or slide past each other. Over time, this movement causes great pressure. When the pressure becomes too great, the rock masses suddenly shift along a crack in the crust, called a fault. The shifting rocks release energy in the form of shock waves. The waves move through the rock in all directions, causing an earthquake. In the most powerful quakes, people thousands of miles away from the center of the quake can feel the ground shake. boundary: confine crack: fessura, crepa to dig: scavare fault: (qui) faglia mine: miniera molten: disciolta A small number of earthquakes have other natural or human causes. The movement of molten rock beneath a volcano can cause an earthquake. The pressure resulting from holding vast amounts of water behind large dams can cause minor quakes. So can underground nuclear explosions and the digging of mines. Most earthquakes take place along the boundaries of the Earth s crustal plates. Scientists record the shock waves produced in an earthquake with an instrument called a seismograph. They measure the strength of a quake in different ways. The Richter scale measures earthquakes based on the amount of energy they release. The weakest earthquakes are close to zero on the scale; the strongest ones measure about 9. The Mercalli scale measures the amount of destruction caused by an earthquake on a scale of 1 to 12. (https://kids.britannica.com/kids/article/ earthquake/353075) plate: placca to release: rilasciare to shift: spostarsi shock wave: onda d urto to slide: scivolare Tectonic plates Rayleigh waves Crust Epicenter 1. All earthquakes can be perceived by people. 2. The earth s crust is fractioned in plates. 3. All plates move in the same way. Love waves Fault P- and S-waves 4. Magma can cause earthquakes. Hypocenter 5. Not all earthquakes have natural causes. 6. The Richter scale is about the effects of earthquakes, the Mercalli scale measures their strength. THE WORKPLACE 241