Overview of NanTroSEIZE:The Nankai Trough Seismogenic

Zone Experiment

Overview of NanTroSEIZE:The Nankai Trough Seismogenic

Zone Experiment

Harold TobinUniversity of Wisconsin – Madison

Masataka KinoshitaJAMSTEC - IFREECo-Chief Project Scientists & Expedition 314 co-Chiefs

for NanTroSEIZE Proponents, Project Management Team, and Expedition 314 – 316 Scientists

NanTroSEIZE transect spans NanTroSEIZE transect spans the up-dip limit of the M8+ the up-dip limit of the M8+ seismogenic asperity seismogenic asperity

3D seismic& drilling transect3D seismic& drilling transect

1944

1946

Inferred Asperity of1944 Tonankai earthquake

(Ichinose et al., 2003)

(Baba and Cummins, 2005)

(Kikuchi and Yamanaka, 2001)

NanTroSEIZE targets an up-dip maximum of large slip in 1944 and the presumed locked portion of the plate interface today

NanTroSEIZE objectives:NanTroSEIZE objectives:Building a Building a distributed observatorydistributed observatory spanning spanning the up-dip end of the interplate seismogenic the up-dip end of the interplate seismogenic

zonezone

~8 planned drilling sites, to depths from ~300 to ~6000+ m ~8 planned drilling sites, to depths from ~300 to ~6000+ m

below the seafloorbelow the seafloor

Core sampling, logging, downhole testing, and long-term Core sampling, logging, downhole testing, and long-term

monitoring – all to provide data on monitoring – all to provide data on fault physics fault physics at several at several

locations in P, T, and structural/diagenetic evolutionlocations in P, T, and structural/diagenetic evolution

Objectives of NanTroSEIZE Document the material properties and state of the plate boundary fault

system at several P-T and lithology conditions, testing hypotheses for stable

vs. unstable frictional behavior.

Investigate partitioning between seismic vs. aseismic processes on the main

plate boundary, through monitoring of seismicity, borehole strain, pore fluid

pressure, and temperature.

Test whether there are interseismic temporal changes in state – including

possible earthquake precursory signals.

Calibrate observations in the broader geophysical volume (3D seismic)

surrounding the boreholes to the rock properties and state.

NanTroSEIZE is primarily about FAULT MECHANICS

NanTroSEIZE:Background on project

organization

NanTroSEIZE:Background on project

organizationSet of IODP Drilling Proposals submitted and reviewed from 2001 - 2004

IODP’s first “Complex Drilling Project” (CDP) designation and first “Project Management Team” (PMT) set up to implement

3D MCS survey funded as Site Survey by NSF-ODP (~25%) and MEXT (~75%), acquired in 2006U

.S. P.I.s: G. Moore, N. Bangs, H. Tobin, S. Gulick, D. Saffer)

Drilling of Stage 1 from Sept 2007 - Feb 2008

Set of IODP Drilling Proposals submitted and reviewed from 2001 - 2004

IODP’s first “Complex Drilling Project” (CDP) designation and first “Project Management Team” (PMT) set up to implement

3D MCS survey funded as Site Survey by NSF-ODP (~25%) and MEXT (~75%), acquired in 2006U

.S. P.I.s: G. Moore, N. Bangs, H. Tobin, S. Gulick, D. Saffer)

Drilling of Stage 1 from Sept 2007 - Feb 2008

3D seismic box

Mega-Splay Fault

Oceanic Crust Decollement

Nankai accretionary wedge3D imaging by pre-stack depth migration

Stages OverviewStages Overview Stage 1 – 2007-2008

Riserless drilling of 8 sites up to ~1400 m depth.

Stage 2 – Planned for 2009 First riser-based deep site drilling at NT2-11 to ~3000 m.

Additional riserless operations at Inputs sites and riserless observatories (“CORKs”)

Stage 3 – Planned for 2011-2012 ?? ~6000 m riser site drilling C0002 (NT3-01) Observatory installation efforts at other sites.

Stage 4 - Long-term monitoring system completion in 2 deep riser boreholes.

Stage 1 – 2007-2008 Riserless drilling of 8 sites up to ~1400 m depth.

Stage 2 – Planned for 2009 First riser-based deep site drilling at NT2-11 to ~3000 m.

Additional riserless operations at Inputs sites and riserless observatories (“CORKs”)

Stage 3 – Planned for 2011-2012 ?? ~6000 m riser site drilling C0002 (NT3-01) Observatory installation efforts at other sites.

Stage 4 - Long-term monitoring system completion in 2 deep riser boreholes.

Chikyu gets underwaySeptember, 2007

First expeditions on Chikyu

71 scientists from 12 countries were onboard for 5 months of continuous operations (Sept 21, 2007 – Feb 5, 2008)

Drilled 33 holes at 8 sites up to 1400 meters below the sea floor

Obtained core samples from active faults and environment

Found major variations in stress orientations, providing evidence for location of the up-dip limit of frictionally locked plate interface

Future plan to drill up to 6000+ meters depth to sample and instrument in and around the seismogenic zone

First expeditions on Chikyu

71 scientists from 12 countries were onboard for 5 months of continuous operations (Sept 21, 2007 – Feb 5, 2008)

Drilled 33 holes at 8 sites up to 1400 meters below the sea floor

Obtained core samples from active faults and environment

Found major variations in stress orientations, providing evidence for location of the up-dip limit of frictionally locked plate interface

Future plan to drill up to 6000+ meters depth to sample and instrument in and around the seismogenic zone

NanTroSEIZE Stage 1:NanTroSEIZE Stage 1:Expeditions 314, 315, and 316Expeditions 314, 315, and 316

Stage 1 drilling on interpreted arbitrary line from 3D seismicStage 1 drilling on interpreted arbitrary line from 3D seismic

Interp. by G. Moore, 2008

NanTroSEIZE Future PlansNanTroSEIZE Future Plans2009: IODP Expeditions 319, 322, 323

Drill and prepare to install seismic / geodetic / hydrologic observatories at 3 sites above seismogenic zone

Core the subduction inputs to basement

2009: IODP Expeditions 319, 322, 323

Drill and prepare to install seismic / geodetic / hydrologic observatories at 3 sites above seismogenic zone

Core the subduction inputs to basement

NanTroSEIZE Future PlansNanTroSEIZE Future Plans2011 Install monitoring systems in cased boreholes:

Seismometer array, Strainmeter, tiltmeter, pore pressure, and temperature

2012 until 20?? Drill with riser system to megasplay fault/plate boundary at

C0002, or equivalent site.

2011 Install monitoring systems in cased boreholes:

Seismometer array, Strainmeter, tiltmeter, pore pressure, and temperature

2012 until 20?? Drill with riser system to megasplay fault/plate boundary at

C0002, or equivalent site.

Link to cabled observatory network for real-time monitoring

Japanese seafloor cabled network DONET will be completed in 2010

NanTroSEIZE IODP borehole observatories will be connected

What has changed since project conception?What has changed since project conception?

Where does the plate boundary lie beneath the forearc basin and mega-splay?

What has changed since the project conception?What has changed since the project conception?

2009 ExpeditionsCall for Participants out now!2009 ExpeditionsCall for Participants out now!

www.iodp.orgwww.iodp.org

NT2-11 Observatory option 1:TD=2500m bsf

BBseismometer is installed at ~1600m to avoid high temperature3 tiltmeters are installed within 9-5/8” section in the accretionary prismPP at the bottom, plus ~1600m (perforated and packer-sealed)