Mohorovičić was born inVolosko,Opatija, where his father (also named Andrija) was ablacksmith, specializing in making anchors. The younger Andrija also loved the sea and married a captain's daughter, Silvija Vernić, with whom he had four sons.[6] Mohorovičić obtained his elementary education in his home town, then continued at thegymnasium of neighbouringRijeka. He received his higher education in mathematics and physics at the Faculty of Philosophy inPrague in 1875, where one of his professors wasErnst Mach. At 15, Mohorovičić knewItalian,English andFrench. Later he learnedGerman,Latin, andAncient Greek.[7]
Mohorovičić c. 1880Detail of a commemorative plaque of Mohorovičić inClementinum, Prague, Czech Republic
In Bakar he was first exposed tometeorology, which he taught at the Royal Nautical School. This influenced him to the extent that he founded the localmeteorological station in 1887. He made systematic studies and both invented and constructed instruments to observe precipitation inCroatia andSlavonia. At his own request in 1891, he was transferred to the secondary school inZagreb where, in 1892, he soon became a head of the Meteorological Observatory inGrič and established a service for all Croatia, while teachinggeophysics andastronomy at the university.[7][8]
On 13 March 1892, he observed thetornado inNovska, which picked up a 13-ton railway carriage with fifty passengers and threw it 30 m. He observed also the "vihor" (whirlwind) nearČazma in 1898 and studied the climate in Zagreb. Mohorovičić was the first person to describe atmospheric rotors with a horizontal axis, which he observed duringbora-wind episodes in the northern Adriatic.[9] In his last paper on meteorology (1901), he discussed the decrease in atmospherictemperature with height. His observations ofclouds formed the basis of his doctoral thesisOn the Observation of Clouds, the Daily and Annual Cloud Period in Bakar presented to theUniversity of Zagreb and which earned him his degree as doctor of philosophy in 1893.[7][8]
On 8 October 1909 an earthquake occurred with itsepicenter in thePokuplje region, 39 km southeast of Zagreb. A number ofseismographs, installed beforehand, provided invaluable data, which led Mohorovičić to new discoveries. He concluded that whenseismic waves strike the boundary between different types of material, they are reflected and refracted, just as light is when striking a prism, and that when earthquakes occur, two waves—longitudinal andtransverse—propagate through the earth with different velocities. By analyzing data from more observation posts, Mohorovičić concluded that theEarth has several layers above a core. He was the first to establish, based on the evidence from seismic waves, thediscontinuity that separates the Earth'scrust from itsmantle. This is now called theMohorovičić discontinuity or (because of the complexity of that name)Moho. According to Mohorovičić, a layered structure would explain the observation of depths where seismic waves change speed and the difference in chemical composition between rocks from the crust and those from the mantle. From the data, he estimated the thickness of the upper layer (crust) to be 54 km.[10] Geophysicists subsequently determined that the crust is 5–9 km below the ocean floor and 25–60 km below the continents, which rest ontectonic plates.Subsequent study of theEarth's interior confirmed the existence of the discontinuity under all continents and oceans.
Mohorovičić assumed that the velocity of seismic waves increases with the depth. The function he proposed to calculate the velocity of seismic waves is called the Mohorovičić law.[11][12] He developed a method for determining earthquake epicenters[13] and constructed curves giving the travel-times of seismic waves over distances of up to 10,000 miles from their source.[14][15] He also proposed the construction of a new type ofseismograph for recording ground horizontal movement, but due to lack of funds the project was never realized.[16]
As early as 1909 Mohorovičić started giving lectures recommending standards that both architects and building contractors should follow - he was ahead of his time in setting some of the basic principles ofearthquake-resistant design.[7][17] Mohorovičić's theories were visionary and were only truly understood many years later from detailed observations of the effects of earthquakes on buildings,deep focus earthquakes, locating earthquake epicenters, Earth models, seismographs, harnessing the energy of the wind, hail-defence and other related elements of the geological body of knowledge known asgeoscience.
His theories and proposals were foundation of the "Zagreb school of seismology", which continued his work.[4] Swedish seismologist M. Båth counted Mohorovičić along with 13 other names among the most important researchers in the field of seismology in the 1900-1936 period.[4]
In 1963, Yugoslavia issued a postage stamp in his hounour on the occasion of the World Meteorological Day.[6] On 23 April 2007,Croatian Post issued stamp in his honour, part of "Famous Croats" series.[18] That same year, theCroatian Monetary Institute and theNational Bank of Croatia issued a gold coin on the occasion of the 150th anniversary of his birth.[6]
A. Mohorovičić (1908). "Epicentri potresa u Hrvatskoj i Slavoniji" [Epicenters of earthquakes in Croatia and Slavonia].Yearly Report of the Zagreb Meteorological Observatory for the Year 1906. Part IV (in Croatian). pp. 15–19.
A. Mohorovičić (1910). "Epicentri potresa u Hrvatskoj i Slavoniji" [Epicenters of earthquakes in Croatia and Slavonia].Yearly Report of the Zagreb Meteorological Observatory for the Year 1909 (in Croatian).
A. Mohorovičić (1911). "Djelovanje potresa na zgrade" [The effects of earthquakes on buildings].Vijesti Hrvatskog društva inženjera i arhitekata (in Croatian).
A. Mohorovičić (1914). "Hodograph der normalen P-Wellen fur eine mittlere Herdtiefe".Beilage zu den Seismischen Aufzeichnungen (in German). Zagreb: Kraljevski zemaljski zavod za meteorologiju i geodinamiku.
A. Mohorovičić (1914). "Hodograph der ersten longitudinalen Wellen eines Bebens (emersio undarum primarum)".Bulletin des travaux de l'Académie Yougoslave des Sciences et des Beaux-arts, Classe des sciences mathématiques et naturelles (in German). Vol. 2. pp. 139–157.
A. Mohorovičić (1915). "Neue Phasen im Anfange des Bildes eines Bebens".Bulletin des travaux de l'Académie Yougoslave des Sciences et des Beaux-arts, Classe des sciences mathématiques et naturelles (in German). Vol. 4. pp. 65–86.
A. Mohorovičić (1915). "Zu dem mittelitalienischen Beben vom 13. Jänner 1915. 2. Beilage zu den Seismischen Aufzeichnungen".Kraljevski zemaljski zavod za meteorologiju i geodinamiku (in German). Vol. 5. Zagreb.
A. Mohorovičić (1915). "Zur Frage der Emergenzgeschwindigkeit. 1".Beilage zu den Seismischen Aufzeichnungen (in German). Vol. 4. Zagreb: Kraljevski zemaljski zavod za meteorologiju i geodinamiku.
A. Mohorovičić (1915). "Zur Frage der Emergenzgeschwindigkeit. 1".Beilage zu den Seismischen Aufzeichnungen (in German). Vol. 4. Zagreb: Kraljevski zemaljski zavod za meteorologiju i geodinamiku.
A. Mohorovičić (1916). "Die Bestimmung des Epizentrums eines Nahbebens".Gerlands Beiträge zur Geophysik (in German). Vol. 14. pp. 199–205.
A. Mohorovičić (1916). "Die Bestimmung des Epizentrums eines Nahbebens".Gerlands Beiträge zur Geophysik (in German). Vol. 14. pp. 199–205.
A. Mohorovičić (1916). "Vorlaufige Mitteilung uber das Beben vom 12. III. 1916".Berichte uber seismische Aufzeichnungen. Zagreb: Kraljevski zemaljski zavod za meteorologiju i geodinamiku.
A. Mohorovičić (1917). "Principi konstrukcije sismografa i prijedlog za konstrukciju nova sismografa za horizontalne komponente gibanja zemlje" [Principles and construction of a seismograph, and a proposal for construction of a new seismograph for recording of horizontal component of ground motion].Rad JAZU (in Croatian). Vol. 217. pp. 114–150.
A. Mohorovičić;S.Mohorovičić (1922). "Hodografi longitudinalnih i transversalnih valova potresa (undae primae et undae secundae)). Part 1. Hodographs" [Hodographs of the longitudinal and transversal earthquake waves (undae primae et undae secundae)].Rad JAZU (in Croatian). Vol. 226. pp. 94–190.
A. Mohorovičić (1924). "A critical review of the seismic instruments used today and of the organisation of seismic service".Rad JAZU. Vol. 14. pp. 38–59.
A. Mohorovičić (1925). "Hodographes des ondes normales P et S soulignees (Pn, P*, S*) et des deux premieres reflexions pour les profondeurs de l'hypocentre de 0, 25, 45, 57 kms".UGGI, Section de Seismologie, A. Travaux Scientifique (in French). Vol. 3. pp. 1–60.
A. Mohorovičić (1926). "Zur Frage der wahren Empfindlichkeit eines Seismographen".Gerlands Beiträge zur Geophysik (in German). Vol. 15. pp. 201–214.
^Mohorovičić, A. (1910)."Das Beben vom 8. X. 1909" [The quake of 8 October 1909].Godišnje izvješće Zagrebačkog meteorološkog opservatorija za godinu 1909 / Jahrbuch des meteorologischen Observatoriums in Zagreb (Agram) für das Jahr 1909 [Yearbook of the meteorological observatory in Zagreb (Agram) for the year 1909] (in German):1–63. Mohorovičić had observed (p.28) that quakes seemed to generate two types of preliminary tremors (i.e., the earliest recorded tremors from a quake): one type was detected only by stations that were up to 300 km from the epicenter and other type was detected only by stations that were 700 km from the epicenter. After calculating the waves' transit times, Mohorovičić concluded (p. 38) that waves from earthquakes were being reflected by a discontinuity located approximately 50 km below the Earth's surface:"Ich entschied mich für eine abgerundete Tiefe von 50 km." (I decided on a rounded-off depth of 50 km.)
^K. E. Bullen (1985).An Introduction to the Theory of Seismology. Press Syndicate of the University of Cambridge.ISBN9780521283892.
^"Discontinuity".gfz.hr. Department of Geophysics, Faculty of Science, University of Zagreb. Retrieved20 January 2015.
^A. Mohorovičić (1916). "Die Bestimmung des Epizentrums eines Nahbebens".Gerlands Beiträge zur Geophysik. Vol. 14. pp. 199–205.
^A. Mohorovičić (1914). "Hodograph der normalen P-Wellen fur eine mittlere Herdtiefe".Beilage zu den Seismischen Aufzeichnungen. Kr. Zem. Zavod Za Meteorologiju I Geodinamiku, Zagreb.
^A. Mohorovičić (1914). "Hodograph der ersten longitudinalen Wellen eines Bebens (emersio undarum primarum)".Bulletin des travaux de 1'Académie Yougoslave des Sciences et des Beaux-arts, Classe des sciences mathématiques et naturelles. Vol. 2. pp. 139–157.
^A. Mohorovičić (1917). "Principi konstrukcije sismografa i prijedlog za konstrukciju nova sismografa za horizontalne komponente gibanja zemlje" [Principles and construction of a seismograph, and a proposal for construction of a new seismograph for recording of horizontal component of ground motion].Rad JAZU (in Croatian). Vol. 217. pp. 114–150.
^A. Mohorovičić (1911). "Djelovanje potresa na zgrade" [The effects of earthquakes on buildings].Vijesti Hrvatskog društva inženjera i arhitekata (in Croatian).
