How did scientist use seismographs to determine the construction of the interior of the earth?

Scientists are able to understand Earth's interior by studying seismic waves.

Seismic waves travel at different speeds when they pass through different types of material, so by studying seismograms, scientists can learn a lot about Earth's internal structure.

the roman republic began to expand when rome fought the punic wars and defeated carthage. the punic wars refer to the series of 3 wars fought among rome and carthage, before it ended in carthage's defeat.