How do geologists study Earth’s Interior?

Hint: The internal structure of the earth is divided into concentric shells such as the outer solid crust, the mantle and the liquid outer core whose flow generates the earth's magnetic field and a solid inner core. People had once thought that the earth was just a simple ball of rock. Recently, geologists have shown that the study of the earth is much more complex. Geology is the study of the earth’s history, its structure and composition.

Complete answer:
Throughout our planet’s long history, its surface has been lifted up or pushed down, bent and broken. Inorder to understand the interior of the earth, geologists examine rocks for clues about what’s inside or underneath the earth by implementing the following steps below:
Evidence from rock samples: Rocks from inside the earth give clues to geologists about the earth’s structure. Geologists have also drilled holes as deep as 12 kilometers into the earth so that they can bring up samples of rock. From these rock samples, a geologist can understand about conditions deep inside earth or from where these rocks were formed.
Evidence from seismic waves: Since there is a difficulty of looking inside the earth, geologists have come up with a new idea or an indirect method of observation . In order to study the earth’s interior, geologists use an indirect method of finding out by using a seismic wave to record details. For instance, when an earthquake occurs, they produce seismic waves.

Note: Geologists are like earth detectives and with experience, they can make use of clues to figure out what is buried under the ground surface. They can also look at stones that have been lined up or the shape of a ripple and tell which way the ancient river that deposited them was flowing.