1. GeoFEM Kinematic Earthquake Cycle Modeling in the Japanese Islands Hirahara, K. (1), H. Suito (1), M. Hyodo (1) M. Iizuka (2) and H. Okuda (3) (1) Nagoya University (2) Research Organization for Information Science and Technology (3) University of Tokyo

2. Outline ・ Present status of developing GeoFEM earthquake cycle simulation module in a local model ( as Drs. Okuda, Nakajima, Kato and Furumura presented in this meeting) ・ Simulation of crustal deformation using kinematic earthquake cycle based on dislocation model ・ Northeast Japan model: 100 years Compare present GPS and 100-year conventional geodetic observations with computed ones Possible slow slip event in early 1900’s ? ・ Southwest Japan model: 300 years GPS observed concentrated deformed zone (NKTZ)

3. Quasi-Static Modeling of Earthquake Cycle Interaction on and between Faults Dynamic Modeling of Earthquake Rupture Wave Propagation in Heterogeneous Media Simulation and Prediction of Strong Motion Interplate Earthquake FaultInland Active Fault Viscoelastic Interaction Frictional Law Earthquake Generation and Strong Motion in 3-D Heterogeneous Media Fault Constitutive Law Plate Subduction

4. Present status of GeoFEM development : Kinematic modeling 3-D viscoelastic parallel FEM （ time domain ） Elastic/Maxwell/Standard linear solid Dislocation model ・ Contact analysis on plate boundaries, active faults Implementation of friction law(R/S F) Plate motion→Quasi-static slip evolution →Dynamic fault rupture→Strong motion In progress:

5. Kinematic Earthquake Cycle (a) Interseismic (b) Coseismic all decoupled Oceanic plate Continental plate ***** locked Continental plate Oceanic plate ***** locked Oceanic plate Continental plate ***** locked Oceanic plate Continental plate ト ＝ ＋ Interplate Earthquake Subduction Steady Motion Back Slip using dislocation (Savage,1983)

6. Present stage of our study ★ Crustal motion modeling Based on dislocation model, Simulate the past and the present crustal motion in Northeast and Southwest Japan, respectively.

7. ★ Slow Slips ・ In 1989 ， 1992 Off Sanriku Strain meters K AWASAKI et al. (1995) ・ the 1994 Off Sanriku Eq. Afterslip （ GPS ） H EKI et al. (1997) ・ 1978 Off-Miyagi Afterslip (Leveling) U EDA et al. (2001) 1978 ～ 1979 1994 ～ 1995 1992 1989 Interplate Earthquakes in Northeast Japan in the last 100 years

8. No.of Nodes ： 26880 No.of Elements ： 24242 A A’ GeoFEM Mesh Configuration (Horizontal View)

9. GeoFEM Mesh Configuration (Vertical View)

10. Sources of Crustal Deformation ４． 1896 Riku’u Earthquake ２． Subduction of AM 0-30 km １． Subduction of PA 15-60 km ３． Interplate Earthquakes Since 1890 （ M>7.4 ） 17 eqs. Assumption of Plate Coupling *100% coupling * Coupling Depth

11. ★ Year Interplate Earthquakes ★ 1936 Kinkazan 1938 Shioya 1940 Shyakotan 1952 Tokachi 1958 Etorof 1964 Niigata 1968 Tokachi 1969 Eastern Hokkaido 1973 Nemuro 1978 Miyagi 1983 Central Japan Sea 1993 Southwest Hokkaido 1994 Off-Sanriku Horizontal Displacement since 1900

12. ★ GPS Observation ★ ★ Computed Result ★ 〇 and × ： 〇 ・ Westward rate of 2cm/yr along the Pacific coast ・ Western Hokkaido × ・ Northern Hokkaido ； Eastward rate ・ Northern Tohoku ； Small rate 1996-1999 Comparison of Recent Horizontal Velocity Field

13. Comparison of Principal Strain Rate in 100 years Observation by GSI [Ishikawa ・ Hashimoto(1999)] Computed result

14. Principal Strain Rate in 100 years Historical Events + Assumed 1930 Slow or the 1896 Afterslip Event Possible Slow Slip

15. ★ Fault Planes ★ ★ Moment Accumulation ★ Backslip Accumulated Mo = 3.3×10 22 (Nm) Seismic Released Mo = 1.37×10 22 (Nm) Aseismic Released Mo = 4.9×10 21 (Nm) Seismic Coupling 42% 57% （ including aseismic slips ） Moment Accumulation

16. GPS observed velocity NKTZ wrt Stable EU 1996-1999 Southwest Japan

17. ★ Assumed tectonic source 1. Subduction of the Philippine Sea plate Coupling zone: 6-30km Backslip rate : 2-4-6cm/yr 2. Eastward motion of the Amurian plate Horizontal velocity: 1cm/yr 3. Subduction of the Pacific plate Coupling zone: 15-60km Backslip rate : 8cm/yr Southwest Japan Nodes ： 24255 Elements ： 21600

18. Considered earthquakes in this study Historical earthquake sequences

19. PHS:Assumed Coupling distribution 3cm/yr

20. Effect of Subducting PHS 10 years after EQ.

21. Effect of Subducting PHS

22. Present Velocity Field due to PHS and Interplate Great Earthquakes Gap Looks like elastic response Visco-elastic Effect dominates

23. Subduction of PA and Eastward motion of AMR

24. Computed Present Velocity Field

25. Comparison with observed data