Dynamic numerical modelling of co-seismic landslides using the 3D distinct element method: Insights from the Balta rockslide (Romania)

Ancient landslides of unknown origin can be found in large numbers mountainous regions; some represent valid markers (pre-)historic natural regimes referring to either long-term evolution or short-term peak events climatic and seismotectonic nature. An example is represented by the Balta rockslide Romanian Carpathian Mountains. Its location seismically active Vrancea-Buzau region, as well its morphological features, deep-seated rupture surface debris volume, raise question failure history with regard a possible co-seismic triggering. A 3D volume based reconstruction slope morphology together field measurements elasto-plastic in-situ rock properties allow estimate pre-failure conditions slope, special regards geological, i.e. flysch bedrock poor fair quality, structural settings, anti-dip bedding crossed main joint family. The reconstructed behaviour was tested under static dynamic forces distinct element code 3DEC, subsequently used simulate scenario 120 s long real earthquake record that leads realistic post-failure Balta. For latter, we observe principally joint-controlled combined internal fracturing undamaged mass. After 230 simulated time, landslide reaches valley bottom maximum displacements 1350 m marked lateral expansion broader extent than source zone width, observed field. Extension this work other pre-historic failures valleys yield valuable new information for future seismic hazard estimations region.