Answer and Explanation:
Theories and scientists make predictions about what could potentially be in the Earth's core. Earth is said to consist of many layers, but scientists ponder what lies in the middle. Earthquakes and volcanoes kind of work together in a way, since they both deal with Earth's energy. And yes, seismic waves do teach scientists about the two, but it's more than that.
Both earthquakes and volcanoes can teach scientists how these natural disasters affect nature. For example, when lava touches a forest floor, or even rock, it can melt everything in it's path. But, it can produce new plant life once the Earth beneath it heals. Earthquakes can help teach scientists about the layers in the Earth and where these spots are most frequent in the world where they appear.
Also, lava from volcanoes can tell scientists that there is some sort of liquid towards the center of the Earth, not only types of solids.
Let me know if you have more questions, I hope this helps.