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Proposals in the System: Hikurangi slow slip- 781-MDP & 781A-Full, Riserless drilling and Observatory Phase Proposals in the process of being developed:

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Presentation on theme: "Proposals in the System: Hikurangi slow slip- 781-MDP & 781A-Full, Riserless drilling and Observatory Phase Proposals in the process of being developed:"— Presentation transcript:

1 Proposals in the System: Hikurangi slow slip- 781-MDP & 781A-Full, Riserless drilling and Observatory Phase 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

2 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, and fluid pressure, flow rates, and geochemistry during slow slip events

3 3 Comparison between Japan trench and Hikurangi—this could make Hikurangi a compelling riser target to help undertand Japan’s subduction zones Japan Trench Hikurangi Fault depth 10 – 15 km 5 – 15 km Mw 6.8 – 7.0 6.5–6.8 Duration 20 – 40 days 14 – 35 days Yoshihiro Ito

4 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

5 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

6 New Ideas for proposals Tuaheni Slides- Ingo Pecher Possible slow moving landslides in region of proposed781-A drilling transect Over pressured fluids and gas from hydrates may cause hydrofractures, producing landslide planes in regions of hydrates (Usually BSR are thought to be slide plane) MeBo, R/V Sonne 70? m cores scheduled in 2015? APL Proposal for 150-200 m boreholes, LWD and pressure cores Mechanisms of slides Role of overpressurization from hydrates



9 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-slip Test model

10 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)

11 (Plaza Faverola et al., in prep.) Transient fluid-flow anomaly, Fluids probably from depth of subduction interface Possible fluid migration paths Slow-slip

12 New Ideas for proposals Comparisons of near trench axis drilling – Shuichi Kodaira (Hikurangi, Tohoku, Nankai, Costa Rica, Sumatra) Drilling of sediments at toe of thrust preserves history 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

13 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-the –toe earthquake

14 Slip at a toe in the Nankai Trough Sakaguchi et al., 2011 High vitrinite reflectance; evidence of frictional heating at the frontal thrust

15 Is there evidence for slip to the toe at Hikurangi? Would also provide a nice compare/contrast to Nankai (south Hikurangi) and Tohoku (north Hikurangi) Potential for tying this into a global study of near-trench seismic behavior (Sumatra, Costa Rica, others?) Hikurangi cores could be done with MeBo as a MSP proposal+during 781-A leg for N. Hikurangi

16 Proposals in progress/new ideasWhat to do? Hikurangi Riser proposalDevelop and submit riser proposal in April 2013 Brothers VolcanoWorkshop 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 FluidsPossible 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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