Andrija Mohorovičić
A Croatian scientist who discovered the boundary between the Earth's crust and mantle by analyzing the speed of earthquake waves.
1857–1936 (age 79)·Croatian seismologist and geophysicist·Birthday: January 23
Biography
Andrija Mohorovičić began his career not as a globe-trotting explorer, but as a meticulous observer at a weather station in Zagreb. His shift to seismology was fueled by a powerful earthquake in 1909, whose shockwaves rippled through the Balkans. While others saw only destruction, Mohorovičić saw data. Scrutinizing the seismographs, he noticed that some waves arrived faster than expected, defying existing models. His brilliant insight was that these waves had refracted off a sharp discontinuity deep underground—a hidden boundary where denser rock began. This layer, now called the Mohorovičić Discontinuity or simply 'the Moho,' defines the base of the Earth's crust. In one stroke, he gave geology a fundamental internal landmark and proved that the secrets of the planet's interior could be decoded from the surface, revolutionizing how we understand the ground beneath our feet.
#1 When Andrija Was Born
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Andrija's Life & Times
The world at every milestone
1857Born
1862Started school
President: Abraham Lincoln
1870Became a teenager
President: Ulysses S. Grant
1873Could drive
President: Ulysses S. Grant
1875Could vote
President: Ulysses S. Grant
1878Turned 21
President: Rutherford B. Hayes
1887Turned 30
President: Grover Cleveland
1897Turned 40
President: William McKinley
1907Turned 50
Financial panic grips Wall Street
President: Theodore Roosevelt
1917Turned 60
Russian Revolution overthrows the tsar; US enters WWI
President: Woodrow Wilson
1927Turned 70
Lindbergh flies solo across the Atlantic; The Jazz Singer premieres
President: Calvin Coolidge"My Blue Heaven" — Gene Austin
1936Died at 79
Jesse Owens wins four golds at the Berlin Olympics
Gas: $0.19/galPresident: Franklin D. Roosevelt"The Way You Look Tonight" — Fred AstaireBest Picture: The Great Ziegfeld
Key Achievements
- Discovered the Mohorovičić Discontinuity in 1909, the boundary between the Earth's crust and the underlying mantle.
- His work provided the first clear seismic evidence for a layered internal structure of the Earth.
- Developed foundational methods for locating earthquake epicenters using data from multiple seismic stations.
- Served as the first director of the Zagreb Meteorological Observatory, building it into a major research center.
Did You Know?
The discontinuity he discovered is universally referred to by the shorthand 'Moho'.
He was also a noted meteorologist and published the first comprehensive study of climate in Croatia.
A crater on the far side of the Moon is named in his honor.
He was a polyglot who could deliver scientific lectures in multiple languages.
““The seismograph is the most sensitive instrument that exists for the study of the Earth's interior.””
