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Investigating subduction processes at the

Hikurangi margin, New Zealand

Laura Wallace (GNS Science, New Zealand, Univ. Texas Institute for Geophysics), Dan Bassett (GNS Science, New Zealand),
Samer Naif (Lamont-Doherty Earth Observatory, Columbia University), Patrick Fulton (Cornell University), Heather Savage
(Lamont-Doherty Earth Observatory, Columbia University), Shuo Shuo Han (Univ. Texas Institute for Geophysics)

A mini-workshop to discuss the latest research results from the In particular, the strong along-strike variations in megathrust
Hikurangi subduction zone (New Zealand), was held on Sunday behavior and characteristics make it an ideal location to investigate
afternoon before Fall AGU began in Washington, D.C. The mini- the physical controls on subduction margin deformation and slip
workshop had a record turnout, with 116 registrants from ten behavior.
different countries. A particular priority of this workshop was to Data acquisition and analysis at the Hikurangi margin are ongoing
get the broader community up to speed on the range of research by scientists from New Zealand, the United States, Japan and Europe.
activities and major experiments underway to better understand Major experiments to investigate Hikurangi subduction processes
the Hikurangi subduction zone, and to facilitate discussion to better have taken place in the last year, including two Integrated Ocean
integrate results between these projects. Discovery Program (IODP) drilling expeditions to investigate slow
Subduction of the Pacific Plate beneath New Zealand’s North Island slip processes (Expeditions 372 & 375), and two seismic experiments
occurs at the Hikurangi subduction margin. The Hikurangi margin with the R/V Langseth and R/V Tangaroa to investigate controls
offers an outstanding opportunity to address many of the key topics on plate coupling and slow slip (Fig. 1). Additional NSF and New
of the GeoPRISMS Subduction Cycles and Deformation initiative, Zealand-funded experiments have taken place in the first few
as outlined in the New Zealand primary site implementation plan. months of 2019.

Figure 1. Map of the North Island and offshore
Hikurangi subduction zone with a summary of some
instrumentation and recent offshore and onshore −37˚
experiments undertaken at the Hikurangi subduction
margin over the last 3 years.
−38˚
Legend
NZ3D seismic survey North
NZ3D OBS deployment Island
More than a hundred attendees from ten NZ3D 6DT seismometer
countries participated in the pre-AGU −39˚ NZ3D cube seismometer
GeoPRISMS mini-workshop to discuss the SAFFRONZ flowmeters
subduction processes at the GeoPRISMS Focus
Site New Zealand Hikurangi Subduction Zone. Exp 372/375 borehole
−40˚

−41˚

South
Island
Hikurangi Trench
−42˚

−43˚
174˚ 175˚ 176˚ 177˚ 178˚ 179˚ 180˚
Legend
SHIRE MCS profile HT-RESIST CSEM profile Bottom Pressure
Recorder (BPR)
SHIRE OBS profile HT-RESIST MT deployment
SHIRE onshore seismometer SAFFRONZ Flowmeters OBS
GeoNET seismometer OBS+BPR
Exp 372/375 borehole GPS-Acoustic

34 • GeoPRISMS Newsletter Issue No. 42 Spring 2019