Naslov
Identification of tectonically active areas in the Pannonian basin: a combination of DEM based morphotectonic and structural analysis of Bilogora Mt. area (NE Croatia)

Autori
Matoš, Bojan ; Tomljenović, Bruno ; Herak, Marijan ; Herak, Davorka ; Takač, Damir

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
11th Workshop on Alpine Geological Studies and 7th European Symposium on Fossil Algae, Abstracts & Field Guides, 7th-14th September 2013, Schladming-Austria. / Schuster, R. - Beč : Berichte der Geologischen Bundesanstalt, 99, 10, 285 p., 2013, 61-62

Skup
11th Workshop on Alpine Geological Studies & 7th European Symposium on Fossil Algae

Mjesto i datum
Schladming, Austrija, 07.09.2013. - 14.09.2013

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Bilogora Mt.; DEM; morphometry; structural modeling; seismogenic potential

Sažetak
Bilogora Mt., which is predominantly composed of highly deformed Pliocene-Quaternary clastic sediments, represents more than 90 km long and 10 km wide young transpressional structure related to the NW-striking Drava basin boundary fault (DBBF). DBBF was reactivated from originally normal into dextral fault accommodating c. 10 km displacement during Pliocene-Quaternary transpression in the southern part of the Pannonian Basin. On-going tectonic activity is documented by historical seismicity reporting several moderate earthquakes of intensity VI°-VIII° MCS in vicinity of larger towns. It is characterized by NE-SW orientation of the greatest horizontal stress direction determined from fault plane solutions of instrumentally recorded earthquakes (3, 5≤ML≤5, 6), indicating steeply NE-dipping, and S-SW dipping seismogenic structures with predominantly strike-slip and reverse motions. Landscape features has been analyzed by DEM raster with 10 m cell resolution. It was modeled and analyzed using ESRI ArcMap 9.x.x. software package with CalHypso, Spatial Analyst, ArcHydro 1.1 and StPro extensions as well as Matlab software. Study area was divided into 130 drainage units. For each unit relative elevation and slope distribution values, drainage unit area-altitude relations (hypsometric integral values) as well as unit absolute asymmetry ratios were calculated. In addition, we analyzed main drainage longitudinal trunk channel statistical values extrapolating parameters of maximum concavity (Cmax), position of maximum concavity (Δl/L), concavity factor (Cf), steepness index (ksn) and concavity index (θ). All calculated geomorphic parameters have been combined and overlayed as rasters, which enable a separation of drainage units characterized by geomorphic parameters that could possibly indicate an on-going tectonic deformation. These units are located between towns of Koprivnica and Pitomača on northeastern slopes and in the vicinity of Daruvar on southwestern slopes, in the northwestern and southeastern part of Bilogora Mt., respectively. To verify about a possible relationship between geomorphic indices and tectonic deformation a set of 72 reflection seismic sections was analyzed using Schlumberger Petrel Seismic to Simulation software. This software enabled construction of structural depth model comprising 6 stratigraphic horizons and more than 50 faults active during the Neogene-Quaternary times. Spatial correlation between geomorphic and structural data proved that calculated geomorphic indices in the northwestern part of Bilogora Mt. correlate well with subsurface fault-related folds of Late Pontian-Quaternary age. These folds are formed in hangingwalls of either normal-inverted or younger reverse faults that cut across the base Pliocene-Quaternary horizon and propagate towards the surface. Vertical offset along these faults is in range between 20-480 m, thus indicating a slip rate of ≤ 0, 1mm/year during the Pliocene-Quaternary times. Using the published empirical geometrical fault-scaling relationships, we estimate that at least some of these faults are capable to generate earthquakes with magnitudes up to 6.86 which are significantly greater than historically reported in Croatian Earthquake Catalogue.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Rudarstvo, nafta i geološko inženjerstvo

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