[moh-haw-roh-vuh-chich, -hoh-] 
| the discontinuity between the crust and the mantle of the earth, occurring at depths that average about 22 mi. (35 km) beneath the continents and about 6 mi. (10 km) beneath the ocean floor. |
| Mo·ho·ro·vi·čić discontinuity (mō'hə-rō'və-chĭch) n. The boundary between the earth's crust and the underlying mantle, averaging 8 kilometers (5 miles) in depth under the oceans and 32 kilometers (20 miles) in depth under the continents. [After Andrija Mohorovičić (1857-1936), Croatian geophysicist.] |
| Mohorovičić discontinuity (mō'hə-rō'və-chĭch) Pronunciation Key
The boundary between the Earth's crust and mantle, located at an average depth of 8 km (5 mi) under the oceans and 32 km (20 mi) under the continents. The velocity of seismic primary waves across this boundary changes abruptly from 6.7 to 7.2 km (4.1 to 4.5 mi) per second in the lower crust to 7.6 to 8.6 km (4.7 to 5.3 mi) per second in the upper mantle. The boundary is estimated to be between 0.2 and 3 km (0.1 and 1.9 mi) thick and is believed to coincide with a change in rock type from basalts (above) to peridotites and dunites (below). It is named after its discoverer, Croatian seismologist Andrija Mohorovičić (1857-1936). |