Mohorovicic Discontinuity, nicknamed "Moho," is the area where the earth's crust meets the earth's mantle. Moho is named after Andrija Mohorovicic (1857-1936), a Croatian meteorologist and seismologist who was fascinated with the faults and movements in the earth's infrastructure which result in earthquakes. The discovery of the Moho was most important because it helped scientists delimit the crust, and recognize a second layer, or mantle, inside the earth. It also helped them determine more accurately where this second layer was located in relation to the earth's crust. In the early 1900s, scientists were almost certain that the Earth, like an onion, was made up of many layers, but they did not know exactly where the layers started and ended.

Using records from a number of Yugoslavian earthquakes, Mohorovicic recognized that the same set of seismic waves appeared twice on a single earthquake record. Because the second...