IODP Nankai Trough Seismogenic Zone Experiment NanTroSEIZE

First Access to the Megathrust Earthquake Zone

Earthquakes, especially those at subduction zones, are among the greatest natural hazards on the planet. The Sumatran earthquake and Indian Ocean tsunami of 2004 demonstrated to the world how devastating these events can be. To learn more about how and why earthquakes and tsunamis occur, the Integrated Ocean Drilling Program (IODP) explores the geology below the seafloor to study Earth processes that evolve over time, ultimately causing violent, unpredictable natural disasters. The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a complex ocean drilling project that will be conducted over several years with multiple expedition teams of scientists from all around the world. NanTroSEIZE attempts for the first time to drill, sample, and instrument the earthquake-causing, or seismogenic portion of Earth’s crust, where violent, large-scale earthquakes have occurred repeatedly throughout history. The Nankai Trough is located beneath the ocean off the southwest coast of Japan. It is one of the most active earthquake zones on the planet. The plan for NanTroSEIZE includes drilling, below the ocean, very deep into the Earth to observe earthquake mechanisms. Samples will be collected in order to study the frictional properties of the rock and sensors are to be installed deep beneath the sea floor to record earthquakes up close. The sensors and sample data are expected to yield insight into the processes responsible for earthquakes and tsunami. The data may shed light on how water and rock interact in subduction zones to influence earthquake occurrence.

Masataka Kinoshita Institute For Research on Earth Evolution, JAMSTEC (Japan) Harold J. Tobin Dept. of Geology and Geophysics, The Univ. of Wisconsin-Madison (USA)

EXPEDITION STAGES

A transect of eight Sites was drilled in 2007 to 2008 to target the shallow part of mega-splay fault and frontal thrust region. Accretionary complex structure, lithology and age, physical properties, and state of stress are documented to characterizing the overall fault systems, setting the stage for deep riser drilling to the seismogenic zone.

Expeditions in FY 2007-2008 [Completed (Feb 2008)]

#	Expedition	Objective	Co-Chief Scientists	Expedition Project Manager	Detail
314	LWD Transect	Logging While Drilling (LWD) at all the Stage 1 sites.	M. Kinoshita (IFREE/JAMSTEC) H. Tobin (Univ. of Wisconsin-Madison)	Moe Kyaw Thu (CDEX)
315	Megasplay Riser Pilot	Shallow branching faults and tectonostratigraphy of the Kumano forearc basin.	J. Ashi (Univ. of Tokyo) S. Lallemant (Univ. of Cergy-Pontoise)	H. Masago (CDEX)
316	Shallow Megasplay and Frontal Thrusts	Coring of the incoming sediments and prism toe.	G. Kimura (Univ. of Tokyo) E. Screaton (Univ. of Florida)	Daniel Curewitz (Syracuse University)

Stage 2 expeditions will drill to prepare for future installation of the Long-Term Borehole Monitoring System by Riser and Riserless drillings in the great earthquake and Tsunamigenic region of the Nankai accretionary prism. Also, investigate input material entering the seismogenic zone, by characterizing the composition, architecture, and state of sediments that will be transported by the subduction system.

Expeditions in FY 2009 [Completed (Oct 2009)]

#	Expedition	Objective	Co-Chief Scientists	Expedition Project Manager	Detail
319	Riser/Riserless Observatory 1	To prepare for future installation of the Long-Term Borehole Monitoring Systems (LTBMS) by Riser and Riserless drillings in the great earthquake and Tsunami-genic region of the Nankai accretionary prism.	Eiichiro Araki (MARITEC/JAMSTEC) Tim Byrne (Connecticut University) Lisa McNeill (University of Southampton) Demian Saffer (Pennsylvania State University)	Nobu Eguchi (CDEX) Kyoma Takahashi (CDEX) Sean Toczko (CDEX)
322	Subduction Inputs	Characterization of composition, architecture, and state of pre-subduction sediments transported to the seismigenic zone.	Michael B. Underwood (Univ. of Missouri) Saneatsu Saito (IFREE/JAMSTEC)	Yusuke Kubo (CDEX)

Expeditions in USFY 2010

#	Expedition	Summary	Co-Chief Scientists	Expedition Project Manager	Detail
332	Riserless Observatory 2	Install a permanent riserless CORK observatory and replacing the currently deployed temporary observatory with a newly designed sensor	To be announced	Sean Toczko (CDEX/JAMSTEC)
333	Inputs Coring 2 and Heat Flow	Sediment coring with downhole temperature measurements and basement coring	Toshiya Kanamatsu (IFREE/JAMSTEC, Japan) Pierre Henry (CEREGE, France)	Sean Toczko (CDEX/JAMSTEC)

Stage 3 is a very challenging expedition that will focus on drilling 6,000–7,000 meters below the seafloor deep into the seismogenic zone and across the plate interface into the subducting crust. Once drilling is complete, an initial monitoring system will be deployed in the borehole. This monitoring system shall remain in place for one to two years, while the "final" long-term monitoring package is readied.

Expedition in FY 2010 [Completed (Aug 2010)]

#	Expedition	Summary	Co-Chief Scientists	Expedition Project Manager	Detail
326	Plate Boundary Deep Riser 1	Prepare the hole for future ultra-deep riser drilling by installing the wellhead and casing	M. Kinoshita (IFREE/JAMSTEC) H. Tobin (Univ. of Wisconsin-Madison)	Nobu Eguchi (CDEX/JAMSTEC)

Stage 4 will install long-term observatory systems into the two ultra-deep boreholes. In Japan, a seafloor fiber-optic network for seismic monitoring and other applications is proposed for deployment in the Kumano Basin region. One exciting possibility is that the NanTroSEIZE boreholes ultimately could be connected to this network in Stage 4, allowing real-time access to earthquake data.

MEDIA & PRESS

PUBLICATIONS/Brochure

Scientific Prospectus Stage 1 Overarching Scientific Prospectus Stage 1 Expedition 314 Scientific Prospectus Stage 1 Expedition 315 Scientific Prospectus   Addendum Stage 1 Expedition 316 Scientific Prospectus   Addendum Stage 2 Expedition 319 Scientific Prospectus Stage 2 Expedition 322 Scientific Prospectus Preliminary Report NanTroSEIZE Stage 1A Expedition 314 Preliminary Report NanTroSEIZE Stage 1A Expedition 315 Preliminary Report NanTroSEIZE Stage 1A Expedition 316 Preliminary Report NanTroSEIZE Stage 2 Expedition 319 Preliminary Report NanTroSEIZE Stage 2 Expedition 322 Preliminary Report Proceedings NanTroSEIZE Stage 1 (Exp. 314, 315 and 316) Brochure NanTroSEIZE Brochure Overview