Andrija Mohorovičić facts for kids

Quick facts for kids Andrija Mohorovičić
Portrait of Andrija Mohorovičić
Born	23 January 1857 Opatija, Austrian Littoral, Austrian Empire
Died	18 December 1936(1936-12-18) (aged 79) Zagreb, Sava Banovina, Kingdom of Yugoslavia
Known for	Eponym for the Mohorovičić discontinuity

Andrija Mohorovičić (born January 23, 1857 – died December 18, 1936) was a Croatian geophysicist. He is famous for discovering the Mohorovičić discontinuity, a key layer inside Earth. Many people consider him one of the founders of modern seismology, which is the study of earthquakes.

Early Life and Learning

Andrija Mohorovičić was born in Volosko, a town near Opatija. His father, also named Andrija, was a blacksmith who made anchors for ships. Young Andrija loved the sea, just like his father. He later married Silvija Vernić, who was a captain's daughter. They had four sons together.

Andrija went to elementary school in his hometown. Then, he continued his studies at a high school in nearby Rijeka. In 1875, he went to Prague to study mathematics and physics. One of his teachers there was a famous scientist named Ernst Mach. By the age of 15, Mohorovičić already knew several languages, including Italian, English, and French. Later, he also learned German, Latin, and Ancient Greek.

Teaching Career

Mohorovičić started his career as a teacher. He taught at a high school in Zagreb from 1879 to 1880. After that, he taught at another school in Osijek. In 1882, he began teaching at the Royal Nautical School in Bakar, which is close to Rijeka. He stayed there for nine years. The work he did in Bakar was very important for his future scientific discoveries.

In 1893, he became a member of the Faculty of Philosophy at the University of Zagreb. He taught geophysics and astronomy there until 1918. In 1898, he became a full member of the Yugoslav Academy of Sciences and Arts in Zagreb. He was also a university professor.

Studying the Weather (Meteorology)

While teaching in Bakar, Mohorovičić became very interested in meteorology, which is the study of weather. He even taught this subject at the Royal Nautical School. His interest grew so much that he set up a local weather station in 1887. He carefully studied the weather and even invented his own tools to observe rainfall in Croatia and Slavonia.

In 1891, he moved to a secondary school in Zagreb. The next year, in 1892, he became the head of the Meteorological Observatory in Grič. He created a weather service for all of Croatia. At the same time, he continued teaching geophysics and astronomy at the university.

On March 13, 1892, Mohorovičić saw a powerful tornado in Novska. This tornado was so strong that it lifted a 13-ton train car with 50 passengers and threw it 30 meters away! He also studied a "vihor" (whirlwind) near Čazma in 1898. He looked into the climate in Zagreb too. Mohorovičić was the first person to describe special atmospheric rotors, which are like horizontal spinning air currents. He saw these during strong bora-wind events in the northern Adriatic Sea.

In his last paper on meteorology in 1901, he wrote about how air temperature decreases as you go higher in the atmosphere. His observations of clouds were so good that they became the basis for his doctoral degree. He earned his philosophy degree from the University of Zagreb in 1893 for his work On the Observation of Clouds, the Daily and Annual Cloud Period in Bakar.

Discoveries in Seismology

Andrija Mohorovičić's most important work was in seismology. On October 8, 1909, a big earthquake happened in the Pokuplje region, about 39 kilometers southeast of Zagreb. Luckily, several seismographs (instruments that record ground shaking) had been set up before the earthquake. These machines collected very important information.

By studying this data, Mohorovičić made amazing discoveries. He realized that when seismic waves (the waves caused by earthquakes) hit the boundary between different types of material inside the Earth, they behave like light hitting a prism. They are both reflected (bounce back) and refracted (bend). He also knew that when earthquakes happen, two main types of waves travel through the ground: longitudinal waves (P-waves) and transverse waves (S-waves). These waves travel at different speeds.

By looking at data from many observation stations, Mohorovičić figured out that the Earth is made of several layers, like an onion, above a central core. He was the first scientist to use seismic wave evidence to show there was a clear boundary, or discontinuity, that separates the Earth's outer layer, called the crust, from the layer below it, called the mantle. This boundary is now known as the Mohorovičić discontinuity, or simply the Moho.

Mohorovičić believed that this layered structure explained why seismic waves change speed at certain depths. It also explained the differences in the chemical makeup of rocks from the crust and the mantle. From his data, he estimated that the crust was about 54 kilometers thick. Today, we know that the crust is thinner under the oceans (5-9 km) and thicker under the continents (25-60 km). These continents sit on huge moving pieces called tectonic plates.

Later studies of the Earth's interior confirmed that the Moho discontinuity exists under all continents and oceans. Mohorovičić also thought that the speed of seismic waves increases as they go deeper into the Earth. He even created a formula, called the Mohorovičić law, to calculate this speed. He also developed a way to find the exact starting point (the epicenter) of an earthquake. He drew special curves that showed how long it would take for seismic waves to travel up to 10,000 miles from the earthquake's source.

Mohorovičić also suggested building a new type of seismograph to record how the ground moves horizontally during an earthquake. However, this project was never built because there wasn't enough money.

As early as 1909, Mohorovičić started giving lectures to architects and builders. He was ahead of his time, teaching them basic ideas for designing buildings that could stand up to earthquakes. His ideas were very forward-thinking and were truly understood many years later. His work helped us understand how earthquakes affect buildings, how to find earthquake epicenters, and much more about the Earth.

Legacy

Andrija Mohorovičić's work is remembered in many ways. A crater on the far side of the Moon is named Mohorovičić in his honor. A high school in Rijeka, Croatia, and a school ship in the Croatian Navy are also named after him. In 1996, an asteroid was named 8422 Mohorovičıć to recognize his contributions to science.

See also

• Project Mohole

Images for kids

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  The house in Volosko where Mohorovičić was born

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  Mohorovičić around 1880

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  Detail of a commemorative plaque of Mohorovičić in Clementinum, Prague, Czech Republic

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  Mohorovičić on a 1963 Yugoslavian stamp