It was originally believed that in the seismic Shadow Zone no seismic waves could be detected at all.But as detection techniques improved,it was realized that faint P waves could be detected there.To what do we attribute the source of these P waves?
A) Slight earthquakes deep within Earth
B) The existence of an almost impenetrable layer of solid iron surrounding the outer core
C) Meteor impacts on the side of Earth away from the Shadow Zone
D) Reflections from a solid inner core

Question

Quizplus · Accepted Answer

The presence of faint P waves in the seismic Shadow Zone is mainly attributed to reflections from the boundary between the liquid outer core and the solid inner core of the Earth. These waves travel through the solid inner core, reflecting back up to the surface and being detected in the Shadow Zone, where direct waves cannot be detected.

It Was Originally Believed That in the Seismic Shadow Zone