NUMO-TR-08-03 Development of Methodologies for the Identification of Volcanic and Tectonic Hazards to Potential HLW Repository Sites in Japan - The Tohoku Case Study - Neil Chapman1, Mick Apted2, John Beavan3, Kelvin Berryman3, Mark Cloos4, Charles Connor5, Laura Connor5, Olivier Jaquet6, Nicola Litchfield3, Sue Mahony7, Warwick Smith3, Steve Sparks7, Mark Stirling3, Laura Wallace3 1 MCM Consulting, Switzerland 2 Monitor Scientific LLC, USA 3 GNS Sciences, New Zealand 4 University of Texas, USA 5 University of South Florida, USA 6 In2Earth Modelling Ltd, Switzerland 7 University of Bristol, UK March 2009 Nuclear Waste Management Organization of Japan (NUMO) 2009 年 3 月 初版発行 本資料の全部または一部を複写・複製・転載する場合は，下記へ お問い合わせください。 原子力発電環境整備機構 技術部 〒108-0014 東京都港区芝 4 丁目 1 番地 23 号 三田 NN ビル 2 階 電話 03-6371-4004（技術部） FAX 03-6371-4102 Inquiries about copyright and reproduction should be addressed to: Science and Technology Department Nuclear Waste Management Organization of Japan (NUMO) Mita NN Building 2F, 4-1-23, Shiba, Minato-ku, Tokyo 108-0014, Japan Phone +81-3-6371-4075 FAX +81-3-6371-4083 ©原子力発電環境整備機構 (Nuclear Waste Management Organization of Japan) 2009 NUMO-TR-08-03 Development of Methodologies for the Identification of Volcanic and Tectonic Hazards to Potential HLW Repository Sites in Japan - The Tohoku Case Study - Neil Chapman1, Mick Apted2, John Beavan3, Kelvin Berryman3, Mark Cloos4, Charles Connor5, Laura Connor5, Olivier Jaquet6, Nicola Litchfield3, Sue Mahony7, Warwick Smith3, Steve Sparks7, Mark Stirling3, Laura Wallace3 1 MCM Consulting, Switzerland 2 Monitor Scientific LLC, USA 3 GNS Sciences, New Zealand 4 University of Texas, USA 5 University of South Florida, USA 6 In2Earth Modelling Ltd, Switzerland 7 University of Bristol, UK March 2009 Nuclear Waste Management Organization of Japan (NUMO) Contents 1 Introduction .......................................................................................................................... 1 2 The Geology and Tectonics of the Tohoku Region ............................................................. 4 2.1 Northern Honshu – Tohoku .......................................................................................... 6 2.2 Basement of Tohoku .................................................................................................... 6 2.2.1 Forearc region ....................................................................................................... 6 2.2.2 Volcanic arc region ................................................................................................ 7 2.2.3 Backarc region ...................................................................................................... 7 2.3 Active Deformation: Earthquakes and Faulting ........................................................... 7 2.4 Example Locations ....................................................................................................... 8 3 Evaluation of Rock Deformation in Tohoku ....................................................................... 10 3.1 Strain Rates from Surface Deformation ..................................................................... 11 3.1.1 Active fault source map and logic tree ................................................................ 11 3.1.2 Uplift and tilt data and development of logic trees .............................................. 13 3.1.3 Active fault strain map and example location calculations .................................. 15 3.1.4 Tilt strain map and example location calculations ............................................... 18 3.1.5 Combined Surface Deformation Strain Hazard ...................................................... 21 3.2 Strain Rates from Global Positioning System (GPS) Data ........................................ 24 3.2.1 What exactly is GPS measuring? ........................................................................ 24 3.2.2 Extracting the component of the GPS signal relevant to rock deformation hazards 26 3.2.3 Application of our proposed method to the Tohoku case study .......................... 27 3.2.4 GPS velocities, uncertainties and logic tree construction ................................... 29 3.2.5 One representative elastic block model for northern Honshu ............................. 31 3.2.6 GPS residual upper plate strain map and example location calculations ........... 33 3.3 Strain Rates from Seismicity Data ............................................................................. 38 3.3.1 Seismicity Dataset ............................................................................................... 39 3.3.2 Logic Tree Structure ............................................................................................ 39 3.3.3 Results and Discussion ....................................................................................... 41 3.4 Strain Rate Comparisons ........................................................................................... 45 3.5 From Strain Rate to Hazard ....................................................................................... 47 3.5.1 Hazard Calculation .............................................................................................. 47 3.5.2 Probability of Exceedance of Threshold Strain Rates ......................................... 51 4 Volcanic Hazard Analysis .................................................................................................. 57 4.1 Introduction to the methodology ................................................................................. 57 4.1.1 Geological Models ............................................................................................... 58 4.1.2 Data Uncertainty .................................................................................................. 60 4.1.3 Probabilistic Assessment of Volcanic Hazard ..................................................... 61 4.2 Alternative Data Sets and Cladistics .......................................................................... 62 i 4.2.1 Method ................................................................................................................ 63 4.2.2 Results ................................................................................................................ 63 4.2.3 Clade-volcano cluster correlations ...................................................................... 63 4.3 Probability Models ...................................................................................................... 65 4.3.1 Spatial Density .................................................................................................... 65 4.3.2 Estimating Spatial Density with Kernel Methods ................................................. 68 4.3.3 Cox process with multivariate potential ............................................................... 68 4.4 Application of Probability Models in Tohoku .............................................................. 70 4.4.1 Kernel Density Estimation ................................................................................... 71 4.4.2 Cox Process Model ............................................................................................. 72 4.5 Assessment of Probability of Volcanic Disruption at 14 Example Locations ............. 74 4.6 Sensitivity to Probability Models ................................................................................. 76 5 Conclusions and Recommendations ................................................................................. 81 5.1 Rock Deformation ....................................................................................................... 81 5.2 Volcanism ................................................................................................................... 81 5.3 Closing Remarks ........................................................................................................ 82 6 References ........................................................................................................................ 84 Appendix The Fourteen Example Locations ii 1 Introduction NUMO is responsible for the siting, development and operation of a deep geological repository for high level waste (HLW) in Japan. The process is expected to take at least 15 years to reach the point of repository construction. During the period before this, NUMO will need to evaluate sites that emerge from the ‘volunteer process’ (whereby local communities have been invited to volunteer to be considered as potential hosts for the repository) and select a preferred site. This evaluation will involve initially surface based and then underground site characterisation work. Underground characterisation work will only take place at the preferred site. Prior to the surface based investigations, volunteer sites will have first had to pass a test of general suitability and NUMO will then have carried out a detailed, literature-based preliminary evaluation of suitability, prior to accepting them as ‘Preliminary Investigation Areas’ (PIAs). Because Japan lies in such a tectonically active region of the world on the Pacific rim (the so called ‘ring of fire’), a key aspect of all these steps is consideration of the susceptibility of a site to future tectonic activity and tectonically driven processes and events. In particular, the potential for volcanic and rock deformation impacts on a repository site needs to be considered at each stage of NUMO’s siting programme. Whilst