Geotechnical reconnaissance of the 2010 Darfield (New Zealand) earthquake

Abstract

On 4 September 2010, a magnitude Mw 7.1 earthquake struck the Canterbury region on the
\nSouth Island of New Zealand. The epicentre of the earthquake was located in the Darfield
\narea about 40 km west of the city of Christchurch. Extensive damage occurred to
\nunreinforced masonry buildings throughout the region during the mainshock and subsequent
\nlarge aftershocks. Particularly extensive damage was inflicted to lifelines and residential
\nhouses due to widespread liquefaction and lateral spreading in areas close to major streams,
\nrivers and wetlands throughout Christchurch and Kaiapoi. Despite the severe damage to
\ninfrastructure and residential houses, fortunately, no deaths occurred and only two injuries
\nwere reported in this earthquake. From an engineering viewpoint, one may argue that the
\nmost significant aspects of the 2010 Darfield Earthquake were geotechnical in nature, with
\nliquefaction and lateral spreading being the principal culprits for the inflicted damage.
\nFollowing the earthquake, a geotechnical reconnaissance was conducted over a period of six
\ndays (10–15 September 2010) by a team of geotechnical/earthquake engineers and geologists
\nfrom New Zealand and USA (GEER team: Geo-engineering Extreme Event Reconnaissance).
\nJGS (Japanese Geotechnical Society) members from Japan also participated in
\nthe reconnaissance team from 13 to 15 September 2010.
\nThe NZ, GEER and JGS members worked as one team and shared resources, information and
\nlogistics in order to conduct thorough and most efficient reconnaissance covering a large area
\nover a very limited time period. This report summarises the key evidence and findings from
\nthe reconnaissance.