New Research Reveals That the Petrinja Earthquake Shifted the Ground by Over 15 Inches

The earthquake that struck near the Croatian town of Petrinja in December 2020, with a magnitude of 6.4, was felt across Croatia and in many neighboring countries. It caused significant damage in the area.

In December 2020, a 6.4 magnitude earthquake struck near the Croatian town of Petrinja, causing significant damage and being felt across Croatia and in neighboring countries. A recent collaboration between Croatian and Hungarian researchers analyzed the horizontal and vertical displacements caused by the earthquake, providing insights within a regional geodynamic context.

The displacements caused by the Petrinja quake have already been estimated in several previous works. The newly published results are methodologically novel in that they use an unprecedented amount of geodetic data to reconstruct three-dimensional motions. In addition to the InSAR data (from Copernicus Sentinel-1 mission), data from three hundred re-occupying GNSS stations of low-order trigonometric and GNSS networks were processed.

The results showed that the magnitude of horizontal displacements in the epicenter of the earthquake was 40 centimeters (15.7 inches) in some places, with a maximum of 20 centimeters (7.9 inches) in the vertical direction.

Historical Context and Tectonic Implications

The last earthquake of this magnitude in the region was the one in Zagreb in 1880. In the 140 years between the two quakes, the horizontal displacement of the region today, measured by GPS stations, of 2-4 millimeters per year – a local manifestation of plate tectonics – would cause a displacement on the order of the displacement observed in the recent quake.

This suggests that displacements due to global tectonics and plate movements in the Petrinja-Zagreb region are realized mostly by individual events, earthquakes, rather than continuous movement.

This is important information not only for Croatia when assessing earthquake safety, but also for the neighboring areas.

Reference: “The Largest Geodetic Coseismic Assessment of the 2020 Mw = 6.4 Petrinja Earthquake” by Marko Pavasović, Drago Babić, Antonio Banko and Gábor Timár, 10 June 2024, Remote Sensing.
DOI: 10.3390/rs16122112