What are Earthquakes?
Earthquakes are the result of the Earth’s crust rubbing and shifting against each other or volcanic and/or magmatic movement. Most earthquakes form when the two side of a fault rub against each other. This results in seismic waves happening, a.k.a. earthquakes.
Where do they occur most often? Why?
Most earthquakes happen along the border of the ocean and continental plates. The Earth's crust is made of several pieces of plates. The plates under the ocean are called oceanic plates, and the others that are not under the ocean are continental plates. The plates are moved around by the movement of a deeper part of the Earth, the mantle that is underneath the crust. These plates are always moving and bumping into each other, pulling away from each other, or right past each other. The plates move at about the same speed that your fingernails take to grow. Earthquakes usually happen when two plates are running into each other or sliding past each other. With this being said, earthquakes happen most around plate borders ( continental and oceanic plate borders). This is where most of the plates move and rub up on each other.
What are the types of seismic waves? Describe/explain each of them.
The three different types of seismic waves are primary waves, secondary waves, and surface waves. Primary waves are the fastest type of seismic wave. They form rocks by changing their volume, which can be done by compressing and expanding rapidly. Secondary waves
are slower than primary waves. They deform rocks by changing their shape. Surface waves are the slowest of the trio and pass around the border of the Earth rather than going through it.
What instrument do seismologists use to measure/detect seismic waves?
Seismometers are instruments that measure and record movements in the ground, including seismic waves caused by earthquakes. Records of seismic waves enable seismologists to map the interior of the Earth, and locate and measure the size of earthquakes.
