Andrija Mohorovicic

by Dragutin Skoko

Andrija Mohorovicic was a prominent Croatian scientist in the field of meteorology and seismology at the end of the nineteenth and in the early twentieth century.

He was born on 23 January 1857 in Volosko near Opatija, where he went to elementary school. He attended secondary school in Rijeka and studied mathematics and physics at the Faculty of Philosophy in Prague in 1875. After graduating, he first taught in grammar school in Zagreb (1879-1880) and then secondary school in Osijek. On 1 November 1882 he began to teach at the Nautical School in Bakar, where he remained for 9 years. In 1891 he was transferred to the secondary school in Zagreb at his own request, and on 1 January 1892 he became the head of the Meteorological Observatory on Gric in Zagreb. In 1893 he became the doctor of philosophy at the Zagreb University. Soon after he was habilitated as private docent, and in 1910 became titular associate university professor. From 1893 to 1917/18 he taught subjects in the fields of geophysics and astronomy at the Faculty of Philosophy in Zagreb. In 1893 he became corresponding member, and in 1898 full member of what was then the Yugoslav Academy of Sciences and Arts in Zagreb. At the end of 1921 he retired, and he died in December 1936. He is buried at the Mirogoj Cemetery in Zagreb.

Work in the Nautical School in Bakar was crucial for the beginning of Andrija Mohorovicic's scientific work. This is where he first came into direct contact with meteorology, which he taught at the Nautical School, and which absorbed him to such a degree that he founded a meteorological station in Bakar in 1887.

When he became head of the Meteorological Observatory in Zagreb (1892) he concentrated on three fields. He gave a scientific interpretation of some meteorological phenomena. In 1901 he was appointed head of the complete meteorological service of Croatia and Slavonia, which he raised to a European level in personnel and equipment. And finally, he gradually extended the activities of the observatory to other fields of geophysics: seismology, geomagnetism and gravitation.

In March 1892 Mohorovicic began the astronomical observation of stars passing through the Gric meridian to establish the precise time. At the beginning of April 1893 he established a network of stations for following thunder storms, and in 1899 he founded hail-defence stations in the Jaska District. At the beginning of 1899 he started a project for research into and harnessing of the energy of the bura in the karst region, because "...this would be so beneficial for our barren littoral".

A. Mohorovicic showed interest in extraordinary meteorological phenomena like the tornado near Novska in 1892, and the vijor (whirlwind) near bazma in 1898. He studied the climate in Zagreb, and in his last paper in meteorology (1901) he discussed the decrease in atmospheric temperature with height.

After the turn of the century Mohorovicic's scientific interest focused exclusively on the problems of seismology. Analyzing the Pokuplje (Kupa Valley) earthquake of 8 October 1909, he advanced insight into the spreading of seismic waves of earthquakes with shallow depths through the Earth. In these studies he was the first in the world to establish, on the basis of seismic waves, a surface of velocity discontinuity that separates the crust of the Earth from the mantle and which was named the Mohorovicic Discontinuity in his honour. Soon after Andrija Mohorovicic, scientists confirmed the existence of this discontinuity under all the continents and oceans.

Mohorovicic's thoughts and ideas were truly visionary and came to expression many years later (the effects of earthquakes on buildings, harnessing the energy of the bura, models of the Earth, deep-focus earthquakes, hail defence, locating earthquake epicentres, seismographs, etc.). The well-known Swedish seismologist M. Bath included Andrija Mohorovicic among the 13 most outstanding seismological researchers in the period from 1900 to 1936.

On 19 December 1936, a day after the death of Andrija Mohorovicic, the Zagreb paper Novosti published the following article: "The scientist Professor Andrija Mohrovicic, member of the Yugoslav Academy of Sciences and Arts, one of the founders of modern seismology, has died. He was a well-known and respected figure in Zagreb, and his scientific work in the field of seismology gained him world recognition. He is today considered one of the founders of modern seismology in the world. Doctor Mohorovicic raised the meteorological observatory in Zagreb from modest beginnings to a completely equipped modern institute that enjoyed world renown, especially in seismic measurements. He also organized the meteorological service in Croatia and Slavonia. At the beginning of his scientific career Doctor Mohorovicic devoted most of his energy to meteorology, but he had most success in the field of seismology and he founded the so-called Zagreb School of world recognition in this field of science."

Article submitted by Prof. Dr. Marijan Herak.