The offshore extension of the Eden-Burnside Fault has been mapped from shallow-penetration seismic reflection profiles. Between Hallett Cove and Port Noarlunga, it parallels the coastline 2 km offshore. The fault separates a coastal platform of thin, deformed Tertiary strata from a much thicker, undeformed sequence of Quaternary and Tertiary strata deposited within the Saint Vincent Basin. Seismic profiles demonstrate an absence of topographic irregularities or surficial stratal displacement over the fault zone. This indicates that surficial dislocation as a result of fault activity has not occurred for at least the past 30,000 years.