Earthquakes Lesson 44 of the geography course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: the lesson at school .
0 Rocks along a crack in the crust, a fault, want to slide past each other but are stuck; the strain builds up for years until suddenly they slip, and the jolt shakes the ground: that is an earthquake. 1 Bend a ruler between your hands: it bends and bends, then snaps, and your hands jump; the rocks store energy the same way and release it in seconds. 2 The shaking spreads out as waves: fast P waves arrive first, slower S waves next, and rolling surface waves last, which do the most damage. 3 Shaking ground rarely kills anyone by itself; falling buildings do, so the best protection is buildings designed to bend and sway instead of crack. 4 Nobody can yet say on which day an earthquake will strike, but scientists can map where the risk is high and how strong the quakes there can be. 5 An earthquake is the sudden shaking when rocks along a fault slip after strain has built up. 6 The point underground where the rock slips is the focus, and the point on the surface right above it is the epicentre, where the shaking is usually strongest. 7 Earthquakes send out fast P waves that push and pull, slower S waves that shake side to side, and surface waves that do most damage; a machine called a seismograph records them. 8 Earthquake size is given by magnitude, and each step up means about 32 times more energy released. 9 The strongest earthquake ever recorded was in Chile in 1960, magnitude about 9.5. 10 In 1755 an earthquake, a tsunami and fires destroyed much of Lisbon, killing tens of thousands of people. 11 Most earthquake deaths are caused by collapsing buildings, not by the shaking ground itself. 12 Earthquake-proof buildings use steel frames, flexible joints and even rubber or sliding bases to soak up shaking. 13 Scientists cannot predict the exact day of an earthquake, but they can map which places are at risk. 14 Britain has hundreds of small earthquakes a year, but almost all are too weak to feel. 15 After a big earthquake come many smaller aftershocks, sometimes for months or years. 16 In an earthquake, people are taught to drop to the floor, take cover under a sturdy table and hold on until the shaking stops. ← previous Moving continents: from Pangaea to todaynext → Tsunamis↑ back to Geography This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/geography/44-earthquakes/