ology ▁and ▁Physics ▁of ▁the ▁Earth ’ s ▁Inter ior . ▁ ▁After ▁the ▁First ▁World ▁War ▁Str as bourg ▁became ▁French ▁and ▁Sie berg ▁moved ▁in ▁ 1 9 1 9 ▁together ▁with ▁the ▁director ▁of ▁the ▁Str as bourg ▁main ▁station , ▁, ▁to ▁the ▁newly ▁established ▁Reich sz ent rale ▁für ▁Er db eben forsch ung ▁in ▁J ena , ▁the ▁prede cess or ▁of ▁today ' s ▁Ge od ynam ics ▁Observ atory ▁M ox a . ▁Under ▁He cker ▁as ▁the ▁director , ▁Sie bert ▁was ▁a ▁department ▁head ▁for ▁macro se ism ics , ▁and ▁a ▁government ▁coun c ill or . ▁Sie berg ▁received ▁his ▁doctor ate ▁from ▁J ena ▁University ▁in ▁ 1 9 2 1 ▁and ▁his ▁hab il itation ▁in ▁ge oph ys ics ▁in ▁ 1 9 2 2 . ▁In ▁this ▁year ▁he ▁was ▁involved ▁in ▁the ▁foundation ▁of ▁the ▁German ▁Se ism ological ▁Society . ▁In ▁ 1 9 2 4 ▁he ▁became ▁an ▁extraordinary ▁professor . ▁After ▁He cker ' s ▁ret irement ▁in ▁ 1 9 3 2 , ▁Sie berg ▁became ▁prov is ional ▁director ▁of ▁the ▁Reich sz ent rale ▁für ▁Er db eben forsch ung , ▁in ▁June ▁ 1 9 3 6 ▁he ▁became ▁its ▁director . ▁At ▁his ▁suggestion ▁and ▁according ▁to ▁his ▁plans ▁the ▁Reich ▁Ministry ▁of ▁Science ▁established ▁the ▁German ▁Reich ▁Earth qu ake ▁Service . ▁ ▁In ▁ 1 9 2 5 ▁Sie bert ▁was ▁awarded ▁the ▁ ▁for ▁his