The ‘Moho’ (Mohorovičić Discontinuity) is primarily identified by a sudden increase in the velocity of which waves?
The Moho is the boundary between the Earth’s crust and the mantle. It was discovered because P-waves traveling through the deeper mantle arrive at distant stations faster than those traveling through the shallower crust. This indicates that the mantle is made of much denser rock (peridotite) than the crust. ANSWER: (C) P-waves
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In 1909 andrija Mohorovičić noticed two sets of P-waves on seismograms from a Balkan earthquake. He concluded that one set had traveled directly through the crust, while the faster set had dipped into a denser layer below and “refracted” back up. This boundary—the Moho—varies in depth, being about 5–10 km under oceans and 30–70 km under continents. This discovery provided the first real map of the Earth’s “skin” and confirmed that the planet is composed of chemically and mechanically distinct layers.