Certain and potential earthquake-induced landslides in Vrancea seismic region

Mihai Micu, Hans-Balder Havenith, Dan Bălteanu, Alexandru Onaca, Anne-Sophie Mreyen, Carmen Cioflan
2017 Proceedings of the 33rd Romanian Geomorphology Symposium   unpublished
Earthquakes are representing across Earth's seismically-active regions a major trigger of small-to-large size landslides. Occurred in form of coseismic or postseismic failures, these processes are controlling the slope denudation, inducing in the mean time significant impacts on fluvial morphology through intense slope-channel coupling. Relict, dormant or active forms resembling like earthquake-induced ones are numerous in the Vrancea seismic region (Curvature sector of the South-Eastern
more » ... ians), at least from a morphological point of view. The purpose of this paper is to outline the morphogenetic framework of such high magnitude and low frequency processes on the basis of several case-studies. The Slon, Zăbala, Zâmbroaia and Mlăjet landslides are known as being triggered by the 1940 and 1977 earthquakes. Two other landslides are showing a very high potential of being as well caused (immediate or delayed) by earthquakes: the deep-seated Balta rock slump (92 ha, 60-80 m thick), a potential co-seismic landslide and the Paltineni debris flow (22 ha, 30-40 m thick), highly likely the result of postseismic evolution of a seismically-triggered slump. The two processes are discussed in terms of morphology (assessed through digital stereographic interpretation of aerial photos and LiDAR-derived hillshade DEM) and internal structure (based on ERT and V/R soundings). The Factor of Safety calculation (Bishop method) analysis showed that, at least for the Balta landslide, an additional driving moment from seismic acceleration was necessary to trigger the movement. Such an approach is important within a multi-hazard risk preparedness and prevention framework, allowing us to define different levels of seismic shaking (in combination with variable climatic background conditions) and the related return periods.
doi:10.15551/prgs.2017.78 fatcat:4e6bpecfbvgm7byep6347b2htm