Tectonic analysis of fault slip data sets

TLDR

Qualitative and quantitative methods for fault slip analysis were developed over the past decade. The study reconstructs reduced stress tensors from slickenside‐derived fault slip directions without assuming fault‑plane orientation, and extends the approach to iteratively separate multiple stress systems in heterogeneous data sets. The methods are limited by data quality, require careful field observations, can be applied to earthquake focal mechanisms, and allow distinguishing successive faulting events.

Abstract

Using data that include the direction and the sense of motion on individual fault surfaces determined by slickenside lineations, it is possible to reconstruct reduced stress tensors that correspond to the orientation of stress axes and to the ratio ϕ = (σ 2 −σ 3 )/(σ 1 −σ 3 ) between principal stress values (σ 1 ≥σ 2 ≥σ 3 , compression being positive). No assumption is made concerning the orientation of fault planes relative to stress axes, so that reactived faults are taken into account as well as newly created ones. Qualitative and quantitative methods for analysis of fault slip data were developed during the last 10 years. The practical limitation of the methods and the necessity for critical field observations are emphasized. These methods can be applied to focal mechanisms of earthquakes. A more complex analysis of heterogeneous data sets, involving an iterative separation of different stress systems, is also discussed. This analysis enables one to distinguish successive faulting events. Careful qualitative study in the field is in all cases essential.