Fault zone architecture of a large plate-bounding strike-slip fault: a case study from the Alpine Fault, New Zealand

Publication type:

Internet publication

Metadata:

Abstract

Abstract. New Zealand's Alpine Fault is a large, plate-bounding strike-slip fault, that ruptures in large (MW > 8) earthquakes. Its hazard potential is linked to its geometrical properties. We conducted field and laboratory analyses of fault rocks to elucidate their influence on its fault zone architecture. Results reveal that the Alpine Fault zone has a complex geometry, comprising an anastomosing network of multiple slip planes that have accommodated different amounts of displacement. Within it, slip zone width is demonstrably not related to lithological differences of quartzofeldspathic lithologies, which vary slightly along- strike. The young, largely unconsolidated sediments that constitute the footwall in some outcrops have a much more significant influence on fault gouge rheological properties and structure. Additionally, seismic investigations indicate that the exposed complex fault zone architecture extends into the basement. This study reveals the Alpine Fault contains multiple slip zones surrounded by a broader damage zone; properties elsewhere associated with carbonate or phyllosilicate-rich faults.

Autoren