Constraints on Complex Faulting during the 1996 Ston–Slano (Croatia) Earthquake Inferred from the DInSAR, Seismological, and Geological Observations

Abstract

This study, involving remote sensing, seismology, and geology, revealed complex faulting during the mainshock of the Ston–Slano earthquake sequence (5 September, 1996, Mw = 6.0). The observed DInSAR interferogram fringe patterns could not be explained by a single fault rupture. Geological investigations assigned most of the interferogram features either to previously known faults or to those newly determined by field studies. Relocation of hypocentres and reassessment of fault mechanisms provided additional constraints on the evolution of stress release during this sequence. Available data support the scenario that the mainshock started with a reverse rupture with a left-lateral component on the Slano fault 4.5 km ESE of Slano, at the depth of about 11 km. The rupture proceeded unilaterally to the NW with the velocity of about 1.5 km/s for about 11 km, where the maximum stress release occurred. DInSAR interferograms suggest that several faults were activated in the process. The rupture terminated about 20 km away from the epicentre, close to the town of Ston, where the maximum DInSAR ground displacement reached 38 cm. Such a complicated and multiple rupture has never before been documented in the Dinarides. If this proves to be a common occurrence, it can pose problems in defining realistic hazard scenarios, especially in deterministic hazard assessment.

Post-collisional mantle delamination in the Dinarides implied from staircases of Oligo-Miocene uplifted marine terraces

“…4 ). However, GPS velocities 48 and fault plane solution data 56 prove that the present-day Adria-Europe convergence 48 , 57 has to be accommodated partly by shortening within the entire Dinarides fold and thrust belt 48 , 58 and in the Dinarides–Pannonian basin transition area 59 .…”

Late Quaternary Evolution of a Submerged Karst Basin Influenced by Active Tectonics (Koločep Bay, Croatia)

“…Koločep bay is a part of a wider area recognized for active tectonics [14,25,[45][46][47]. It is characterized by moderate-to-strong earthquakes that are the result of the subduction of the Adriatic microplate under the External Dinarides [25].…”

“…It is characterized by moderate-to-strong earthquakes that are the result of the subduction of the Adriatic microplate under the External Dinarides [25]. The most recent significant earthquake with a magnitude of 6.0 occurred near Ston in 1996 with a hypocenter at 15 km [14,[48][49][50]. The mainshock was felt around 400 km away, with numerous aftershocks within 50 km from the main epicenter, which lasted for a year [14].…”

“…Thus, the RSL is the sum of the eustatic, tectonic and glacial-hydro-isostatic influences in a certain area [7,[9][10][11], whereas the weight and compaction of the sediment cover can also contribute [6]. The Adriatic Sea is a tectonically active area [12][13][14]. Therefore, it is only possible to reconstruct the RSL.…”

“…The Elafiti Islands form a chain of islands and islets (Šipan Island, Koločep Island, Lopud Island, Jakljan Island, Olipa Island, Tajan Islet, Crkvina Islet, Ruda Islet, Kosemč Islet, and Ruda Islet) that extend in a NW-SE direction. The wider region is tectonically active and characterized by moderate-to-strong earthquakes [14,25,26]. One of the most widespread and successful research methods in the study of the Quaternary sediment successions is the application of acoustic mapping techniques using a sub-bottom profiler [29][30][31][32].…”