The ground beneath our feet is not as solid as it seems. The surface of Earth is made up of several tectonic plates, thick slabs
of rock that can be up to about 100 kilometers thick. These plates are floating, actually moving along on molten rock that is circulating below Earth’s crust. Earthquakes occur where two plates rub together, either as they move alongside each other or slide above or below one another. From time to time, the jagged, rocky edges of the plates stick together. When the pressures get too great, the rock snaps and the plates lurch, sometimes moving several feet in just a few seconds. The greater the movement, the more powerful the earthquake. Earthquakes are also common near active volcanoes. Here, it is the movement of magma and not tectonic plates that cause earthquakes. The magma, or molten rock, pushes into solid rock, eventually splitting it. This type of earthquake is generally much weaker than the type that occurs along plates.
During earthquakes, the earth shakes. That means that man-made structures, especially those not built to hold up against an earthquake, can fail. Walls and foundations can crack, buildings can fall, roads and bridges can be damaged, and even railroads can be bent or snapped apart. This direct shaking is probably the most obvious effect of earthquakes, but there are more. Sometimes, even mountains can’t stand up to the shaking. Mountains or hills that are unstable, with loose soil, can experience landslides, which can block roads or damage buildings. Another effect of earthquakes occurs when soil is saturated with water and starts to move and flow like quicksand. This is called liquefaction and can lead to more damage to man-made structures. Tsunamis are another very visible effect of earthquakes. When the sea floor drops or raises, a huge amount of water is displaced. As this water moves toward the land, it forms a series of waves much higher than normal, commonly 10 to 20 meters. These waves can flood coastal communities, often causing even more damage than the original earthquake.
Choose the best summary of the article.
A) There are two main causes of earthquakes. One major cause is is the movement of tectonic plates along a fault line. Another major cause is when the magma of an active volcano moves the tectonic plates it can cause an earthquake. There are many effects of earthquakes. One damaging effect are tsunamis.
B) There are many different effects of earthquakes. One major effect of earthquakes are walls and buildings collapsing. This is usually caused by the direct shaking of the buildings. Another major effect of earthquakes are tsunamis. Another major effect is the soil can become saturated and can cause quick sand.
C) Earthquakes are very dangerous natural disasters. One of the most famous earthquakes was the 1906 earthquake in San Francisco. This earthquake was so bad that it destroyed the entire city! There was another major earthquake in Japan. This earthquake caused a tsunami. There was actually more damage due to the tsunami than the earthquake in Japan.
D) There are many different causes of earthquakes. One major cause of earthquakes is the movement of tectonic plates below the Earth's surface. When the plates move together they rub against each other and this can cause an earthquake. Another major cause of earthquakes happens near active volcanoes. When the magma from the volcano heats up enough this can cause the plates to move.
