Question

Which evidence recorded at seismic stations following an earthquake supports the inference that Earth’s interior changes from solid rock to molten iron and nickel at the mantle-core boundary?

Answer 1

During an earthquake, waves radiate out spherically from the epicenter and reach the surface. There is usually a shadow zone on the earth's surface approximately 104 to 140 degrees of angular distance above the epicenter of the earthquake where no waves are recorded by seismographs. This is because P-waves are refracted by a liquid medium during transmission in the liquid outer core while S-waves cannot transmit through a liquid medium. This means that the interior outer core of the earth is molten.