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Japanese Segmentation Perspective

Japanese Segmentation Perspective. Yasuo AWATA Active Fault Research Center, Geol.Surv.Japan, AIST. WGCEP workshop at Caltech, March 15, 2006. Contents. Earthquake-Segment by the ERC - 5-km threshold Behavioral-Segment by the AFRC,GSJ - 2-km threshold - 21-km-long in average

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Japanese Segmentation Perspective

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  1. Japanese Segmentation Perspective Yasuo AWATA Active Fault Research Center, Geol.Surv.Japan, AIST WGCEP workshop at Caltech, March 15, 2006

  2. Contents • Earthquake-Segment by the ERC - 5-km threshold • Behavioral-Segment by the AFRC,GSJ - 2-km threshold - 21-km-long in average - New relationship between D and L

  3. Probabilities of Shaking for Coming 30 Yearsby ERC of the Government (2005) • Active faults • Earthquakes along subducting plate • Other earthquakes

  4. Active Fault Research Project in Japan • 1995 - 2005 • Evaluated by ERC • Single scenario • Earthquake segment • 5-km-threshould

  5. Best-Estimated Earthquake-Segmentby ERC • 5-km-thresould( Matsuda, 1990) • 145 best-estimated earthquake segments • 12 paleoseismological segments

  6. Behavioral Segments for Multiple Scenario(AFRC,GSJ) • Variability of Earthquake Segment

  7. Multi-Segment Rupture of 1999 Ismit Earthquake Awata et al. 2003 • 6 Geometric Segments • 5-6 Seismological subevents Kikuchi, 1999

  8. Behavioral-Segment & Paleoseismicity • Geometric Segments Behavioral, Paleoseimic Segment Toda et al. (2003)

  9. “Persistent” Behavioral Segment • Variability of rupture length :40-80 to 600 km • Constant slip for each cycle Kondo et al. (2004)

  10. “Persistent” Behavioral Segment • Variability of rupture length :40-80 to 600 km • Constant slip for each cycle Kondo et al. (2004)

  11. Segmentation of 15 Surface Ruptures in Japan • Paleoseismicity and Rupture Process • Segment length <= 35 km • Size of discontinuities <=2-10 km

  12. Scaling laws between D and L • Dmax is proportional to earthquake segment length

  13. Scaling laws between D and L • Dmax is proportional to earthquake segment length • Dmax is proportional to behavioral segment length

  14. Behavioral Segment v.s. Earthquake Segment

  15. Behavioral Segment v.s. Earthquake Segment

  16. Behavioral Segment v.s. Earthquake Segment • Largest b-segment

  17. Behavioral Segment v.s. Earthquake Segment • Largest b-segment • Average b-segment

  18. Criteria for Behavioral Segment • Geometry :fault Jog >= 2 km :fault bend >=20 deg. • Paleoseismicity

  19. Geometry of a Behavioral segment Jog Jog

  20. Be-Segments in Japan -Fault Length • 431 behavioral-segments; Length >= 10 km, Slip rate >= 0.1 mm/y • Maximum length : ca. 70 km

  21. Behavioral Segments - Fault Length 145 major earthq. segs. (by ERC, 2005) ca. 290 behavioral segs. • 431 behavioral-segments; Length >= 10 km, Slip rate >= 0.1 mm/y • Maximum length : ca. 70 km

  22. Behavioral Segments - Fault Length • Average :21 km • Mostly :<= 45 km

  23. Behavioral Segments-Slip per Event • Paleoseimological data from 54 segments • Maximum : 9 m/event

  24. Fault Length v.s. Slip per Event • Dave = 1.2 x 10E-4 L ca.60% of Dmax

  25. Best-Estimated Earthquake Segments • 5-km-thresould( Matsuda, 1990) • 431 b-segments are grouped into 256 e-segments • Largest e-segment consists of 15 b-segments

  26. Scaling Laws for B & E-Segments

  27. Scaling Laws for B & E-Segments

  28. Scaling Laws for E & B-Segments

  29. Scaling law for Behavioral Segment • 1891 to 2000

  30. Scaling law for Behavioral Segment • 1931 Fuyun CH • 1995 Sakhalin RU • 1999 Chi-Chi TW • 2005 Kashmir RK

  31. Scaling law for Behavioral Segment • B & R Province (dePolo et al.,1991) • 1992 Landers

  32. Scaling law for Behavioral Segment • 1943 Bolu • 1999 Izmit • 1999 Duzce

  33. Scaling law for Behavioral Segment

  34. Summary • Behavioral-Segment - 2-km threshold - 21-km-long in average - New relationship between D and L • Best-Eastimeted Earthquake-Segment - 5-km threshold • Further Study for Multiple Earthquake Scenario - Geometry, Stress transfer, G-R relation

  35. Hierarchy ofsegment boundaries andlarge earthquakesKoji

  36. 20th century segmentation ONLY Segmented faulting as a FACT NOT an idea, NOT a model Need and worthwhile testing

  37. Repeated? NO! Based on Ambraseys and Finkel (1995), --most rupture zones are not defined.

  38. Stationary?

  39. Predictable? Cascade? Characteristic? Quasi-periodic?

  40. Bolu-Mudrnu 1943--1944

  41. Sub-characteristic or sub-A type earthquakes Characterize ‘HARD’ segment boundary ZONE

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