Japanese white paper for INVEST, Bremen Japan Drilling Earth Science Consortium (J-DESC) Ver. Sep. 2009 Contents Executive Summary ............................................................ 1 I. Life and Ecosystem in Deep Biosphere and Subseafloor Aquifers .................................................. 4 1. Introduction ........................................................................................................................ 4 2. Important themes of deep-biosphere research .......................................................... 4 2-1. Extent of Biosphere ....................................................................................................................... 4 2-2. Ecological roles of geo-fluids and thermal energy ................................................................ 5 2-3. Biogeochemical functioning, fluxes and ecological roles ...................................................... 5 2-4. Modern proxies for the past biosphere and ecosystem........................................................ 6 3. Analytical and technological development ................................................................. 6 4. Projects for Deep Biosphere presented in the Japanese workshop........................ 7 II. Earth’s Interior .................................................................................. 10 Abstract ................................................................................................................................... 10 i. Breakthrough the Discontinuities: 21 Century Mohole ....................................... 11 Abstract ................................................................................................................................... 11 1. Introduction ........................................................................................................................ 12 2. Nature of Moho ................................................................................................................ 12 2-1. What is the Moho and how does it look like? ......................................................................... 12 2-2. What operates in the Moho? ...................................................................................................... 12 3. Architecture and compositions of the oceanic crust ................................................... 13 4. Alteration processes and the frontiers of deep biosphere ....................................... 13 5. Criteria for site selection and description of potential sites ..................................... 14 6. Technology and strategy ................................................................................................ 14 ii. Arc crust and mantle evolution: The origin of along- and across-arc heterogeneities ..................................................................................................17 Abstract ................................................................................................................................... 17 1. Origin of 3-dimentional variation in the arc, mantle and crust ............................... 18 1.1. Introduction ..................................................................................................................................... 18 1.2. Key scientific questions ................................................................................................................. 18 1.3. Key observations ........................................................................................................................... 19 1.4. 3-D arc project (AAA variations): Using arc inputs and outputs .......................................... 19 2. Expected new outcomes and capabilities .................................................................... 20 3. Path to achieving the goals ............................................................................................ 20 iii. Paleomagnetic problems to be solved by IODP beyond 2013 .......................... 24 Abstract ................................................................................................................................... 24 1. Introduction ........................................................................................................................ 25 2. Paleomagnetic problems to be solved ......................................................................... 25 2.1. Constraining geodynamo models ............................................................................................... 25 2.2. Possibility for orbital modulation of the geomagnetic field, and a link with paleoclimate .......................................................................................................................................................... 26 2.3. Hotspot motion and true polar wander .................................................................................... 26 3. Implementation strategy ................................................................................................. 26 4. Technology to be developed ......................................................................................... 27 III. Building a Scientific Understanding of Geohazards.................................................................... 29 Abstract ................................................................................................................................... 29 i. Exploration into catastrophic earthquakes #1: Approaches from shallow geological record .................................................................................................................30 Abstract ................................................................................................................................... 30 1. Introduction ........................................................................................................................ 31 2. Geologic signatures of the past earthquakes ............................................................ 31 3. New approaches .............................................................................................................. 32 4. Answers to the 8 questions at INVEST .......................................................................... 33 Appendix ................................................................................................................................ 36 ii. Exploration into catastrophic earthquakes #2: Approaches from integration of drilling, monitoring, and numerical modeling ...........................................................37 Abstract ................................................................................................................................... 37 1. Introduction ........................................................................................................................ 38 2. Ocean drilling for understanding of deformation process in earthquake cycles . 38 3. Ocean drilling for clarifying composition and structure of seismogenic faults ..... 39 4. Integration into comprehensive earthquake faulting model ..................................... 40 5. Implementation.................................................................................................................. 41 Appendix ................................................................................................................................ 45 iii. Ocean Transform Fault Drilling and Water Injection: An Active Experiment to Trigger a Moderate Earthquake .........................................................................46 Abstract ................................................................................................................................... 46 1. Introduction ........................................................................................................................ 47 2. Scientific Motivation ......................................................................................................... 47 3. Possible Location for Experiment ................................................................................... 48 4. Technical Considerations ................................................................................................. 48 5. Related Activities .............................................................................................................. 49 6. Societal Relevance ........................................................................................................... 49 7. Active Experiments ........................................................................................................... 49 iv. Exploration into unprecedented volcanic catastrophes in the ocean: unveiling impact of gigantic caldera-forming eruption ...........................................................51 Abstract ................................................................................................................................... 51 1. Why ‘gigantic caldera-forming eruption in the ocean’? ........................................... 52 2. Understanding sequence and variation of eruptive events ...................................... 53 3. Unveiling recurrence history ........................................................................................... 54 4. Challenge to get a perspective view of ‘large silicic magmatic system’ ............... 55 5. Understanding global Geohazard ..............................................................................