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Proposals in the System:
Hikurangi slow slip- 781-MDP & 781A-Full, Riserless drilling and ObservatoryPhase
Proposals in the process of being developed:
Hikurangi deep riser drilling phase
Ideas for New Proposals:
Brothers Volcano (Cornel de Ronde)
Tuaheni Slides (Ingo Pecher)
Porangahau Fluid Flow & Slow Slip (Ingo Pecher)
Near Trench Axis drilling-comparative study of Japan, Hikurangi, Costa Rica,
Sumatra (Shuichi Kodaira)
Earth in Motion Summary- Jim Mori, Laura Wallace
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Proposals in Progress
Hikurangi Slow Slip
Understand the causes of slow slip events
Drilling target is an interface dominated by aseismic
creep (in distinct contrast to Nankai)
Coring and logging will provide information about
physical conditions in region within and above slow
slip events. Incoming plate section will reveal
protolith of rocks in the SSE source further down.
Monitoring changes in strain, tilt, seismicity, andfluid pressure, flow rates, and geochemistry during
slow slip events
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3
Comparison between Japan trench and Hikurangithis
could make Hikurangi a compelling riser target to help
undertand Japans subduction zones
Japan Trench Hikurangi
Fault depth 10 15 km 5 15 km
Mw 6.8 7.0 6.56.8Duration 20 40 days 14 35 days
Yoshihiro Ito
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Main discussion points for further developing
Hikurangi slow slip project
Riser proposal to reach source of slow slip events ( ~ 5.5 km )
Plan to submit riser proposal in April 2013
Need to coordinate funding for observatory (riserless and riser),3-D site survey, 3D VSP, OBS+pressure gauge deployment
Identify fault(s) of large earthquakes and slow slip events
Great interest in physical mechanisms, friction characteristics,
fluid conditions, comparisons to other regions (Tohoku)
Important to obtain sample of fault zone (difficult coring)
Fluid and Pressure monitoring in deep borehole
Need some casing deformation measurement
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New Ideas for proposals
Brothers Volcano- Cornel de Ronde
Volatiles coming to seafloor, end members of flow
rates and fluid composition at one volcano
Workshop in Europe in November
Proposal submission in April 2013?
Caldera formation
Exsolved gas from magma
Formation of hydrothermal minerals
Biological communities
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New Ideas for proposals
Tuaheni Slides- Ingo Pecher
Possible slow moving landslides in region of proposed781-Adrilling transect
Over pressured fluids and gas from hydrates may
cause hydrofractures, producing landslide planesin regions of hydrates
(Usually BSR are thought to be slide plane)
MeBo, R/V Sonne 70? mcores scheduled in 2015?
APL Proposal for 150-200 m boreholes, LWD and pressure cores
Mechanisms of slides
Role of overpressurization from hydrates
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New Ideas for proposals
Porangahau Ridge Fluids (central Hikurangi margin)
Large scale gas volumes outside of GHSZ (Gas Hydrate Stability
Zone)
South of Hikurangi proposal area, slow slip interval different
more fluids
Episodic slow slip events may cause fluid flow.
Transient fluid flow suspected from heat flow anomaly, resistivity,
seismic velocities.
Propose boreholes with LWD (temperature), pore water chemistry,
pressure cores, observatory (too much for APL?). Could this be a
MeBo (+MeBo observatory), or potentially a future (well down the
track) JR proposal? Probably needs more surface investigations.
Constrain fluid flow budgets, fluid sources during slow-slipTest model
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Seafloor thermal gradient
Massive discrepancy to BSR thermal gradient
May point towards transient anomaly (i.e., advective heatflow pulse)
(but may be caused by bottom-water temp. fluctuations)
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(Plaza Faverola et al., in prep.)
Transient fluid-flow anomaly,
Fluids probably from depthof subduction interface
Possible fluid
migration paths
Slow-slip
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New Ideas for proposalsComparisons of near trench axis drillingShuichi Kodaira
(Hikurangi, Tohoku, Nankai, Costa Rica, Sumatra)
Drilling of sediments at toe of thrust preserveshistory of previous earthquakes
Shallow holes (~100-200 meters) and piston coring
Alternate site HSM10-A in 781-A near toe, could drill ~200 m during
drilling for 781-A. Submit MSP proposal to use MeBo to do along
strike transect of ~200 m cores through Hikurangi toe
Understand the near trench earthquake rupture history Slip behavior of splay faults (vitrinite reflectance, turbidite
paleoseismology, others?)
Need to modify current conceptual model for subduction
interface behavior and shallow seismic faulting on megathrust
Slip in this region controls tsunami size Importance for hazards
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IODP
Trench-filled sediment preserve a long term record of slip-
to-the-toe earthquake
Along trench axis drilling transect to spatial
and temporal record of slip-to-thetoe
earthquake
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Slip at a toe in the Nankai TroughSakaguchi et al., 2011
High vitrinite reflectance;evidence of frictional heating
at the frontal thrust
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Is there evidence for slipto the toe at Hikurangi?
Would also provide a
nice compare/contrastto Nankai (southHikurangi) and Tohoku(north Hikurangi)
Potential for tying thisinto a global study ofnear-trench seismicbehavior (Sumatra,Costa Rica, others?)
Hikurangi cores could bedone with MeBo as aMSP proposal+during781-A leg for N.Hikurangi
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Proposals in progress/new ideas What to do?
Hikurangi Riser proposal Develop and submit riser proposal in
April 2013
Brothers Volcano Workshop in Europe, November 2012.
Possible JR pre-proposal (or full proposal
if mature enough??) for April 2013.
Tuaheni Slides (Hikurangi margin) Submit APL for 781-A drilling. MeBo
coring will happen in the area in 2015
Porangahau Fluids Possible MeBo proposal? Ideas around
this still need some development. May
require some form of observatory.
Comparative trench axis study: along-
strike transect of Hikurangi thrust front
Submit MSP proposal (to use MeBo)+we
will try to do shallow drilling (~200 m) at
north Hikurangi toe during the 781-A
riserless drilling
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