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The identification of capable faults is crucial for reliable seismic hazard assessments. To identify geochemical signatures characterizing recent, near-surface faulting, we analyzed the mineral and bulk-rock compositions of a range of fault rocks. We compare the compositions of two faults in central Japan that displace the same granitic unit, but record distinct geological histories: the capable Shiraki–Nyu Fault and a minor, incapable fault. Brownish gouge along the Shiraki–Nyu Fault (representing the principal slip surface) records MnO enrichment and FeO depletion and has a positive Ce anomaly, which was likely produced through oxidation reactions. Compositional mapping of outcrop and core samples from the Shiraki–Nyu Fault indicates that compositional changes (Mn- and Fe-oxide and/or oxyhydroxide precipitation along the principal slip surface) were driven by the fault-driven upward migration and oxidation of reduced fluids from depth to the near-surface. Mapping also indicates that Mn-rich gouge (and ultracataclasite) has undergone brecciation due to recent shallow-level faulting. In the Mn-rich gouge, Ce, Ba, and Y may have been enriched through co-precipitation and/or sorption onto the Mn oxide surfaces. Pale gray gouge from the principal slip surface of the minor incapable fault records no oxidation-related chemical changes. However, anastomosing/grid-like fractures filled with dark gray clay, which cut the pale gray gouge yield elevated MnO and Ba concentrations, low FeO concentrations and positive Ce anomalies, as well as high halloysite abundances. These chemical changes are attributed to post-faulting infiltration of oxidized surface water rather than repeated faulting. We show that geochemical analysis, combined with detailed geological observations, can be used to determine the spatial distributions of elements in heterogeneous fault zones, and contribute to the identification of recent, near-surface faulting events. • Chemical changes due to oxidation of upward migrated reduced fluids were detected. • The oxidation reaction prevails along a principal slip surface of a capable fault. • Geochemical analysis for fault rocks can contribute to identifying capable faults. [ABSTRACT FROM AUTHOR]

A probabilistic framework that considers the variability and uncertainty of the ground motions caused by earthquakes and the parameters of the slope material is proposed to assess the seismic stability of rock slopes. A stochastic ground motion simulation method, which reflects certain earthquake scenarios and site characteristics, was used to generate accelerograms as seismic inputs. Then, the probabilities of failure (P f) of the slopes when subjected to earthquake ground motions were computed via Monte-Carlo simulations based on the simulated ground motions and the decoupled Newmark permanent-displacement analysis. An example rock slope was used to illustrate the proposed procedure and verify its rationality. The results showed that the magnitudes of the earthquakes and the source-to-site distances had significant influences on the seismic stability of the slopes. For an earthquake of the same magnitude, the P f of the slope decreased rapidly as the source-to-site distance increased. In addition, given the same source-to-site distance, the P f of the slope increased steadily as the magnitudes of the earthquakes increased. Also, it was found that the influence of coefficient of variation of the slope's shear strength parameters (i.e., c , φ) was not negligible when the uncertainty of earthquakes was not considered. However, it may be overshadowed by the significant influence of a great earthquake, especially when the variability of ground motions is taken into account. The results that were obtained agreed well with observed earthquake-induced landslide phenomena and the statistical data of two typical earthquakes that occurred in Japan and China, which implies that the proposed method is accurate. • A probabilistic approach to assess rock slope seismic stability is proposed. • The uncertainties associated with earthquakes and slope were considered simultaneously. • Influence of earthquake and variability of slope's strength parameters was investigated. • The results agreed well with the observed earthquake-induced landslide phenomena. [ABSTRACT FROM AUTHOR]