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 Years by ERC of the Government (2005)  Active faults  Earthquakes along subducting plate  Other earthquakes

4 Active Fault Research Project in Japan ■ ■ Evaluated by ERC Single scenario Earthquake segment 5-km-threshould

5 Best-Estimated Earthquake-Segment by 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  6 Geometric Segments  5-6 Seismological subevents Kikuchi, 1999 Awata et al. 2003

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

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

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 of segment boundaries and large earthquakes Koji

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 Characteristic?Quasi-periodic? Predictable? Cascade?

40 Bolu-Mudrnu

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