With the order N.36 of the Allied Military Government, the Seismic Station of Trieste is detached from the Thalassographic Institute and takes the name of Geophysical Observatory. On this occasion, the state-owned land, movable assets and property is divided up. The founder was Prof. Carlo Morelli, who ran the Observatory (Director and President) until 1975. After the bombing of 10 June 1944, with the consequent destruction of the building in Viale Romolo Gessi 2, the Observatory, together with the Thalassographic Institute, was housed in a 5-room flat owned by the University in Via Corsica (now Via del Lazzaretto Vecchio).

The Observatory is divided into five sections: Seismic, Gravity and Magnetism, Geoelectric and Geochemistry, Radioactivity, Geothermal and Ultrasound, Marine Geophysics.

A two-storey building is built on state land around the Seismic Station (p.c. 5792, sheet 107 of the State Property Office) in Viale R. Gessi n.4.

A campaign of gravimetric surveys on land and at sea begins in order to compile a gravimetric map of Italy for hydrocarbon exploration.

The Government Commissioner for the Free Territory of Trieste requests that the Geophysical Observatory be granted legal status under the supervision of the Ministry of Public Education. Laboratories, a library and other offices are built around the Seismic Station.

The first seismic survey at sea in Italy, in the Gulf of Trieste, was carried out on behalf of Agip. The Italian Navy's ship Abete was used for the campaign. Acquisition campaigns in the Adriatic Sea, Mediterranean Sea and Black Sea followed.

Together with SACLANT of La Spezia, OGS began collaboration with the International Bathymetric Chart of the Mediterranean (IBCM) with a series of bathymetry, geomagnetism and gravity cruises in the Ligurian and Tyrrhenian Seas on the SACLANT ships "Aragonese" and "Paolina". The programme ended in 1965 after covering 112020 km.

Under the aegis of the Commission for Large Seismic Profiles (DSS - Deep Seismic Sounding), deep seismic refraction seismic began, based on the use of large quantities of explosives, made available by the war remnants to be destroyed. For the execution of the "big bangs" at sea, the OGS uses the ship Mango, a torpedo boat of the Italian Navy.