Aardbevingen
What happes during an earthquake?
The word eartquake exists contains two words earth and quake. We live at the earth. At the picture you see inside the earth. The crust of the earth mesures about 30 km. Beneath the crust is the mantle of the earth. It consists of heavy pieces of rock. These rocks are very hot. When you go deeper into the earth it gets hotter. Between the rocks there is a thick liquid. The liquid mass is also very hot. It is boiling and the big rocks move Sometimes this boiling mass presses against the crust of the earth the crust starts moving. This is an earthquak. This moving develops cracks in the surface of the earth. You feel the earth shake. It feels like what you feel when a heavy truck passes by. But this shaking is a lot stronger.
What happes during an earthquake?
Pieces of the crust of the earth move apart. This is because of the movement of the big pieces of earth's crust on which the continents lie. These pieces move continually. In doing so they bump into each other. A crack in the crust develops. Sometimes the crack is about 300 km long. As long as the Netherlands! Big area's of land sink in. Houses fall down. Even big buildings like churches and hospitals.
Earthquakes develop when rocks move to each other. Sometimes two slabs of the earths's crust collide and stick sometime to one and other, buiding up tension. When they finally break loose, it gives on enormous earthquake.
The earth often moves. But usually we do not notice it. The movements are to weak. The strenght of an earthquake is mesured with a seismograph. This word means mesurer of vibrations. Everywhere in the world are seismograps. At the photo you see how the earth-movements are drawn on paper. There are light and heavy earthquakes. They get a number from 2 till 9. This list is called the Richter-scale. A light quake has a 2 at the Richter-scale. Five at the Richter-scale is a heavy movement which can cause great distruction. The most heavy earthquakes are between 8 and 9. They destroy everthing.
There exist not only earthquakes. The bottom of the ocean can also move. We call this a sea-quake. A see-quake is in fact an earthquake. The earth's crust does not end at the beach. It can happen that the sea bottom sinks. The sea-water moves strongly. Waves of 30 meter can develop. That is as high as a 10 story buildings
Waves made by a sea-quake are called tidal-waves. They make enormous floods and destroy eveything at the coast.