Spatial patterns of geomorphic surface features and fault morphology based on diffusion equation modeling of the Kumroch Fault Kamchatka Peninsula, Russia

Remote sensing data sets are widely used for evaluation of surface manifestations in active tectonic areas. This study utilizes ASTER GDEM and Landsat ETM + data sets with Google Earth images draped over terrain models. This study evaluates the surrounding surface geomorphology of the study area with these data sets and the morphology of the Kumroch Fault using diffusion modeling to estimate diffusion constants (κ), as well as to estimate slip-rates by means of real ground data measured across fault scarps by Kozhurin et al. (2006). The study area is located southeast of the Bezymianny Volcano within the Central Kamchatka Depression. It is part of the Kumroch Fault Zone. The area contains numerous geomorphic features indicative of active deformation, such as fault scarps, ponds, offset streams, and glacier moraines. TER GDEM and Landsat ETM + data together with Google Earth imagery were used to create accurate geomorphic maps of specific sites within the study area along the western flank of the East Kamchatka Range. Previous studies have estimated the time elapsed since slip initiation of the faulted surface on the Kumroch Fault and the slip-rate by dividing the offset of moraines by the age of the ruptured surface. Slip-rates along the Kumroch Fault vary from 2.0 mm/yr–2.5 mm/yr, determined from previous 14C studies with time frames of 11.5 ka to 14 ka. Other slip-rates for the Kumroch Fault were determined from previous studies through tephra and stratigraphic chronology. These produced rates of 0.6 mm/yr, with time frames of 3.2 ka–10.5 ka. Models of the evolution of fault scarp morphology provide the amount of time elapsed since slip initiated on a faults surface. They may therefore provide more accurate estimates of slip-rate than those calculated by dividing scarp offset by the age of the ruptured surface. Profile modeling of scarps collected by Kozhurin et al. (2006) show that the scarps were formed by several events distributed over time. They were evaluated using a constant slip-rate (CSR) solution which yields a value A/κ (1/2 slip rate/diffusivity). Time elapsed since slip initiated on the fault is determined by establishing a value for κ and measuring total scarp offset. For this study, CSR nonlinear modeling assisted in estimates of κ which along the Kumroch Fault range from 8 m2/ka to 14 m2/ka. Slip-rates have been estimated to range from 0.6 mm/yr to 1.0 mm/yr since 3.4 ka–3.7 ka. This method provides a quick and inexpensive way to gather data for a regional tectonic study and establish estimated rates of tectonic activity.