11:00 AM - 11:15 AM
[SCG58-02] Revisiting the slip-weakening friction: probe into the true source properties from off-fault measurements
Keywords:Slip-weakening friction, Dynamic rupture, Friction experiment
To answer the question, we utilize a large-scale direct shear apparatus at NIED to monitor near-fault strain change during labquakes. By comparing our strain data with common slip-weakening model predications at various locations progressively away from the fault, we see systematically a decrease in apparent peak friction and an increase in apparent breakdown zone size. These features reflect the smearing out of the strain field away from the sharp rupture front. On the other hand, the initial strain before failure and the residual strain after the breakdown process are less sensitive to the sampling location, because the strain field is more homogeneous at those locations without sharp features. By fitting the strain data with templates created from a specific slip-weakening model, we are able to estimate the true source properties during labquakes within the framework of that model. If more data points were available, it would be even possible to probe the true “rupture distribution function” (Andrews, JGR 1976). In any case, our study suggests that care be taken when interpreting measurements during labquakes, especially when sharp features are involved during the rupture breakdown process (e.g. at a scale more than two times smaller than the source-recorder distance). Given the well-known Lorentz contraction effect, we may never be able to directly measure certain rupture properties at speed very close to the limit speed, which ultimately requires some indirect approaches.