ISTerre seminar

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Active tectonics of the Petrinja Fault, Croatia: Present-day rupture and Quaternary activity

Tuesday 2 December 2025 - 11h00

Maxime Henriquet - Géoazur
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The Mw 6.4 Petrinja earthquake that struck Croatia in 2020 is one of the strongest recent intracontinental events in Europe. Understanding the seismic cycle of continental faults in slowly deforming regions is difficult due to their long recurrence intervals and limited monitoring. I will present results from the multi-institutional “EU-Team,” formed after the event to investigate both the 2020 rupture and the Late Quaternary evolution of the Petrinja fault system. First, geomorphological and subsurface data reveal a complex fault geometry and cumulative offsets along strike. Radiocarbon and cosmogenic dating of displaced fluvial terraces indicate a minimum long-term slip rate of ~0.2 mm/yr, significantly higher than previous hazard estimates. Near-surface geophysical surveys and six paleoseismological trenches also confirm sustained Quaternary activity. Second, geodetic observations (fast-static, GNSS, optical correlation, InSAR) refine the 2020 rupture and coseismic slip. Elastic inversion shows a shallow (<7 km) dextral event with >1.2 m surface offsets and a possible deeper slip patch to the southeast. Comparison of geodetic and field measurements suggests that >70% of the slip was released at the surface. The comparison of long-term and coseismic deformation patterns points to a transpressive setting in which strain is distributed across several structures, consistent with an immature and segmented continental fault system.

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Organizing team : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

Informations de visio :

https://univ-grenoble-alpes-fr.zoom.us/j/92956342169?pwd=atRbmXkR3hcDaXyMw5rsnD8AbkUqdG.1