Characterisation of Surface Fault Rupture for Civil Engineering Design

Abstract

Lifelines crossing active faults are vulnerable to damage during surface faulting earthquakes. The design of mitigation measures requires detailed knowledge of fault location, rupture zone width, and the distribution of strain within the fault zone. Although the general magnitude of surface ruptures can be characterised by empirical relationships, behaviour at a specific location is harder to forecast. To understand displacement distribution within the damage zone we need to examine historical surface ruptures. Recent earthquakes (e.g., Wenchuan, 2008; Darfield 2010) provide the opportunity to study the effects of fault geometry, near surface materials and along-strike location on the damage zone width and strain distribution, allowing the development of preliminary empirical models for surface rupture characterisation. As well as presenting these models this paper evaluates current fault investigation practice and describes an alternative approach to defining potential surface rupture zones using existing geologic data, providing a cost-effective, reasonable and rational basis for characterising site-specific rupture hazard.