Features of Seismically-Induced Geological Processes in Fault Zones of Pribaikal’e (based on structural and GPR data)
O. V. Lunina, A. S. Gladkov
Based on geological, structural and GPR data, features of seismically-induced geological processes in the Delta and Mondy active fault zones have been investigated. Traces of rupturing, liquefaction and subsidence have been found in trenches and radargrams. The deformations are often interrelated and the ruptures preceding the sinkholes and injection dikes under seismic impact play a key role in that. Using the OKO-2 GPR equipment with AB-250M and ABDL «Triton» antennas, we revealed the differences in the pattern of seismogenic dislocation zones formed in Quaternary lithologies under dominating transcurrent regime in the western termination of the Tunka valley and tension regime in the central part of the Baikal basin. The rupture deformations associated with the Mondy fault in vicinity of the village of Mondy constitute the zones of contiguous near-vertical fractures. In the Delta fault, they form a stepped system of normal faults. Liquefaction features have been revealed in the southwestern outskirt of the village of Inkino at a depth of 2,5–2,7 m in one GPR profile and 1,5–2,68 m in another GPR profile. In the Mondy fault zone, in front of a sinkhole, subsidence takes place over the system of the near-vertical fractures up to depth of ~4 m that coincides with maximum depth of seasonable frost of gravel-pebble sediments of the Tunka valley. In whole, the performed studies have showed a high informative value of GPR method in combination with geological and structural observations for detection of traces of seismically-induced geological processes.
rupturing, liquafaction, subsidence, earthquake, fault, ground penetrating radar, Pribaikal’e