Liquid earth molten rock - Lava - Wikipedia

Mohorovicic Seismic Discontinuity
Seismic stations within about 200 km of a continental earthquake (or other seismic disturbance such as a dynamite blast) report travel times that increase in a regular fashion with distance from the source. But beyond 200 km the seismic waves arrive sooner than expected, forming a break in the travel time vs. distance curve. Mohorovicic (1909) interpreted this to mean that the seismic waves recorded beyond 200 km from the earthquake source had passed through a lower layer with significantly higher seismic velocity.

1854, "molten metal," from melt (v.). In reference to a type of sandwich topped by melted cheese, 1980, American English.

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