Holocene surface-rupturing earthquakes on the Dinaric Fault System, western Slovenia

Abstract

Abstract. The Dinaric Fault System in western Slovenia, consisting of NW–SE-trending, right-lateral strike-slip faults, accommodates the northward motion of Adria with respect to Eurasia. These active faults show a clear imprint in the morphology, and some of them hosted moderate instrumental earthquakes. However, it is largely unknown if the faults also had strong earthquakes in the late Quaternary. This hampers our understanding of the regional tectonics and the seismic hazard. Geological evidence of co-seismic surface ruptures only exists for one historical event, the 1511 Idrija earthquake with a magnitude of ∼ M 6.8, but the causative fault is still disputed. Here we use geomorphological data, near-surface geophysical surveys, and paleoseismological trenching to study two of these faults: the Predjama Fault and the Idrija Fault. In a paleoseismological trench across the Predjama Fault we found deformation features that may have been caused by an earthquake between 13–0.7 ka, very likely not earlier than 8.4 ka. At the Idrija Fault, a surface-rupturing earthquake happened around 2.5 ka. We show that instrumental and historical seismicity data do not capture the strongest events in this area.

Structural Complexity and Seismogenesis: The Role of the Transpressive Structures in the 1976 Friuli Earthquakes (Eastern Southern Alps, NE Italy)

“…At present, GPS measurements reveal for the Friuli region 2-3 mm/year of shortening [2,[35][36][37], which is absorbed by both NW-SE-trending high-angle strike-slip structures in the easternmost Friuli area and western Slovenia [6,7,38], and by reverse WSW-ENE-to WNW-ESE-striking neo-Alpine frontal ramps in the Veneto and Friuli pre-Alpine area [3].…”

“…Recent paleoseismological analyses on the NW-SE strike slip fault system of eastern Italy and western Slovenia revealed Holocene surface rupturing referable to the 1511 event across the Colle Villano-Borgo Faris-Cividale fault system [30], across the Idrija [38,44] and Predjama faults [38].…”

When it comes to Earth observations in AI for disaster risk reduction, is it feast or famine? A topical review

“…Furthermore, proxy data [e.g. sedimentary seismites as indicators of past earthquakes as in Doughty et al (2014) or the use of 'trenching' through the surface expressions of faults to identify, sequence, and date past seismic events using, for example, radiocarbon dating of organic debris as in Grützner et al (2021)] can extend earthquake occurrence records by years, decades, or centuries. This approach has also been used to reconstruct other types of natural hazards [e. The quality of in-situ data is another important characteristic.…”

Revealing Subtle Active Tectonic Deformation: Integrating Lidar, Photogrammetry, Field Mapping, and Geophysical Surveys to Assess the Late Quaternary Activity of the Sava Fault (Southern Alps, Slovenia)

“…They are even more useful in high-relief areas with high precipitation and erosion rates, dense vegetation, and low fault slip rates, where geomorphic indicators of fault activity tend to disappear rapidly or are reshaped by non-tectonic processes [2]. Using highresolution DEMs in such an environment can help to recognize small-scaled geomorphic indicators for fault activity, enabling us to infer fault slip rates (e.g., [3][4][5][6][7]) and locate paleoseismic trenches to study past seismicity (e.g., [8][9][10][11]). In addition to investigating surface deformation, shallow subsurface investigations, including geophysical techniques with a range of tens of meters, can confirm the presence of young tectonic deformation along faults, help to precisely constrain their location, and understand the shallow geometry of the deformation structure [8,[12][13][14][15].…”