EARTH 520
Plate Tectonics and People

Andrija Mohorovičić

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<p><img alt="ภาพถ่ายของAndria Mohorovicic.gif" src="https://upload.wikimedia.org/wikipedia/commons/thumb/e/e5/%E0%B8%A0%E0%B...
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<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Andrija Mohorovicic was born on January 23, 1857 in Volosko, Opatija, now more commonly known as Croatia.  The son of a blacksmith with a passion for open seas, the elder Mohorovicic worked on the shipyard forging steel into anchors.  Influenced by his father's love for the sea, Andrija married a captain's daughter and had four children, all sons.  Upon graduating from the University of Prague in 1875 with degrees in mathematics and physics, Mohorovicic stayed close to home and spent several years teaching elementary and secondary education.  He then moved on to the Royal Nautical School in Bakar after receiving an appointment to teach meteorology and oceanography.  His love for the study of weather and the atmosphere resulted in him establishing a meteorological station in Bakar in 1887 and became its director in 1892.  in 1893, he became a corresponding faculty member in philosophy at the University of Zagreb Main Technical School where he taught geophysics and astronomy.  Mohorovicic received his Ph.D. in philosophy in Zagreb 1897.</p>
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<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Andrija Mohorovici's most renowned contribution to geology and the plate tectonics theory is his discovery of the separate layers between the earth's crust and mantle, appropriately named the Mohorovicic discontinuity, or Moho.  His interest in seismology began around 1900 in his middle 40's, at a rather unusual time in his scientific career after spending much time devoted to meteorology.  Although there is much speculation to this shift in interest, it is suspected that since the town of Zagerb was regularly devastated by earthquakes and rattled by tremors, it motivated Mohorovicic to install seismographs in the basement of his meteorological observatory to learn more about seismology.  During an earthquake on October 8, 1909 in the region of Pokuplje, 35 kilometers from Zagreb, Mohorovicic excitedly ran to his seismographs in the observatory to check if they had recorded the event.  Using his seismographs and with the aid of other seismograph recordings across Europe, Mohorovicic was able to not only locate an earthquake's epicenter, but his study of seismogram recordings allowed him to discover the existence of a boundary between the crust and mantle, the Moho.</p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><img src="http://geology.com/articles/images/moho-mohorovicic.gif"></p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Mohorovicic's seismogram analyses revealed that seismic waves propagate through the earth in two forms, labeling them p- and s-.  Some seismograms recorded the arrivals of p- and s-waves at differing times while other seismographs recorded only p-waves.  Mohorovicic drew the conclusion that the earth's interior must have some boundary or layers of rock with differing properties, chemical compositions, densities, to alter the velocity of seismic waves as they propagated through the earth's interior, yet seismic wave velocity was a function of increasing depth.  Mohorovicic proposed this as the Mohorovicic Law.</p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><img src="http://www.earthscrust.org.au/science/historic/img/moho.gif">&lt...
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">With these findings, Mohorovicic was able to estimate the thickness of these newly discovered layers.  Within the earth's outer layer, crust thickness was estimated to be 54 km.  Further seismological research now estimates the depth to the Moho discontinuity on the continental crust is between 25 - 60 km and 5 - 9 km along the ocean crust.</p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><img src="http://faculty.buffalostate.edu/bergslet/Moho.jpg">                        <img src="http://www.gfz.hr/sobe-en/photo/hodokrone.jpg"></p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><span style="font-size:10px;"> Mohorovicic's travel-time curve from seismogram analyses during a 1910 earthquake event.</span></p>
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<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Mohorovicic spent much time eary in his scientific career studying meteorology, clouds, atmospheric flow patterns.  To better his observations on cloud formations, he built his own cloud studying scope, his nephoscope.  With his research, he published his doctoral thesis, "On the Observation of Clouds, the Daily and Annual Cloud Period in Bakar", which would earn him his Ph.D. in Philosophy in 1893.  Because of Mohorovicic's achievements as a meteorologist, he began to pubish weather forecasts in daily newspapers, the first Croatian to do so.  Mohorovicic was recognized by his country of Croatia for setting high standards in the meteorological field and unifying meteorological service in Croatia.</p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><img src="http://callisto.ggsrv.com/imgsrv/FastFetch/UBER1/ZI-2FCZ-2007-DEC00-IDSI...                          </p>
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"> <img src="http://callisto.ggsrv.com/imgsrv/FastFetch/UBER1/ZI-2FCZ-2007-DEC00-IDSI...
<p style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;"><span style="font-size:10px;">        Mohorovicic's illustrations of clouds from nephoscope observations.</span></p>
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<li style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Was able to speak English, Italian, French, German, Czech, Latin, and Greek</li>
<li style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">All his publications [over 40], he was the sole author</li>
<li style="margin-top: 0px; margin-bottom: 20px; outline: 0px; font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Pioneered many ideas behind principle design engineering of earthquake resistant construction such as reinforcing joints within building skeletons, beams, and walls; building resonance and soil foundation studies; avoiding soft sediment foundations for building sites</li>
</ul>
<h3 style="margin-top: 0px; margin-bottom: 5px; outline: 0px; font-family: 'aleo regular', sans-serif; font-size: 20px; line-height: 1.2; font-weight: normal; color: rgb(68, 68, 68);">Bibliography</h3>
<p><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Herak, Davorka & Marijan, Seismological Society of America  (2007). "Andrija Mohorovicic (1857 - 1936) -- "On the occasion of the 150th anniversary of his birth."  [srl.geoscienceorld.com/content/78/6/671]</span></p>
<p><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Herak, Marijan, Dept. of Geophysics, Univ. of Zagreb, Studia Geophysica et Geodaetica (2012), vol. 56, iss. 1.  "Andrija Mohorovicic -- 2010-centennial of the discovery of the Moho", pp. 293-298  [link.springer.com/article/10.1007/s112200-011-0076-4]</span></p>
<p><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Editors, Encyclopedia Britannica, "Andrija Mohorovicic - Croatian Geophysicist" </span><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">[www.britannica.com/biography/</span><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">Andrija Mohorovicic]</span></p>
<p><span style="font-family: 'open sans', helvetica, sans-serif; font-size: 14px; line-height: 20px;">King, Hobart, "Mohorovicic Discontinuity, the Moho", [www.geology.com/articles/mohorovicic discontinuity.shtml]</span></p>