Why are there earthquakes ?A Question A Day
You can’t feel it, but under your feet, the earth is moving. The surface of the planet is like a giant jigsaw puzzle with moving pieces. The jigsaw puzzle pieces are called tectonic plates. these plates move a few centimeters every year in different directions. In some parts of the world, these plates meet head on and rub against each other, and that liberates a huge amount of energy: earthquakes.
But what makes the earth… quake?
The plates are in constant movement. When 2 plates collide, energy builds up. The plates rub against each other. over the years, underground rock is compressed. All of a sudden, when the tension gets too strong, the rock snaps and all the energy is released. The neighbouring rocks vibrate. this vibration travels through the ground in all directions. on the surface, it’s an earthquake. The more the energy has built up for a long time before being released, the bigger the earthquake. To measure earthquakes, we talk about magnitude. an earthquake with a magnitude of less than 3 is not felt by humans. From magnitude 5 onwards, the most fragile buildings are hit; over 7, all the buildings are damaged! The most powerful earthquake ever recorded was magnitude 9.5. it was in chile in 1960. The earthquake in nepal on 25 april 2015 was of magnitude 7.9. this was too strong for the fragile buildings of this poor country to resist.
Nom de l'auteur : Jacques Azam
Producteur : Milan Presse, France Télévisions
Année de copyright : 2018
Publié le 23/07/18
Modifié le 03/06/22