What causes earthquakes?
A. Blocks of crust slide against one another, often at plate boundaries
B. Pressure builds up in the molten rock beneath Earth's crust and causes it to shake
C. Tectonic plates break apart into smaller plates, and the crumbling causes shaking
D. Sudden motions in Earth's mantle cause the crust to shift
A. Blocks of crust slide against one another, often at plate boundaries
The correct answer is A. Blocks of crust slide against one another, often at plate boundaries.
The correct answer is A. Blocks of crust slide against one another, often at plate boundaries.
Earthquakes are primarily caused by the movement of tectonic plates, which are large, rigid blocks of the Earth's crust. These plates float on the semi-fluid asthenosphere beneath them. At plate boundaries, the edges of these plates can interact with each other in different ways.
One common type of plate interaction is called a transform boundary, where two plates slide past each other horizontally. As the plates slide, they can get stuck due to friction. However, the motion of the plates keeps pushing against each other, causing stress to build up over time.
Eventually, the stress becomes too great, and the friction holding the plates together is overcome. This leads to a sudden release of energy, resulting in an earthquake. During the earthquake, the blocks of crust that were stuck together suddenly slip and slide past each other, releasing the built-up stress. The energy released during the earthquake travels through the ground in the form of seismic waves, which cause the shaking and destruction we associate with earthquakes.
So, to summarize, earthquakes are primarily caused by the movement of tectonic plates and the release of built-up stress when these plates slide past each other at plate boundaries.