Here's why:
* The Moho is the boundary between the Earth's crust and the upper mantle.
* Seismic waves travel faster through denser materials. The mantle is denser than the crust, causing a significant increase in wave speed as they cross the Moho.
* This increase in speed is a key indicator used to identify the Moho.
Important Note: While the Moho is the primary location for a sharp increase in seismic wave speed, there are other zones within the Earth where similar changes occur, such as the boundary between the upper and lower mantle.
