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Japanese Segmentation Perspective

Yasuo AWATAActive Fault Research Center, Geol.Surv.Japan, AIST

WGCEP workshop at Caltech, March 15, 2006

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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

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Probabilities of Shaking for Coming 30 Yearsby ERC of the Government (2005)

Active faults Earthquakes along subd

ucting plate Other earthquakes

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Active Fault Research Project in Japan

■ 1995 - 2005

■ Evaluated by ERC

Single scenario

Earthquake segment

5-km-threshould

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Best-Estimated Earthquake-Segmentby ERC

5-km-thresould ( Matsuda, 1990) 145 best-estimated earthquake segments 12 paleoseismological segments

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Behavioral Segments for Multiple Scenario(AFRC,GSJ)

Variability of Earthquake Segment

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Multi-Segment Rupture of 1999 Ismit Earthquake

6 Geometric Segments 5-6 Seismological subevents

Kikuchi, 1999

Awata et al. 2003

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Behavioral-Segment & Paleoseismicity

Geometric Segments Behavioral, Paleoseimic Segment

Toda et al. (2003)

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“Persistent” Behavioral Segment

Variability of rupture length :40-80 to 600 km Constant slip for each cycle

Kondo et al. (2004)

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“Persistent” Behavioral Segment

Variability of rupture length :40-80 to 600 km Constant slip for each cycle

Kondo et al. (2004)

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Segmentation of 15 Surface Ruptures in Japan

Paleoseismicity and Rupture Process Segment length <= 35 km Size of discontinuities <=2-10 km

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Scaling laws between D and L

Dmax is proportional to earthquake segment length

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Scaling laws between D and L

Dmax is proportional to earthquake segment length Dmax is proportional to behavioral segment length

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Behavioral Segment v.s. Earthquake Segment

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Behavioral Segment v.s. Earthquake Segment

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Behavioral Segment v.s. Earthquake Segment

Largest b-segment

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Behavioral Segment v.s. Earthquake Segment

Largest b-segment Average b-segment

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Criteria for Behavioral Segment

Geometry :fault Jog >= 2 km :fault bend >=20

deg.

Paleoseismicity

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Geometry of a Behavioral segment

Jog Jog

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Be-Segments in Japan - Fault Length

431 behavioral-segments; Length >= 10 k

m, Slip rate >= 0.1

mm/y

Maximum length : ca. 70 km

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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.

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Behavioral Segments - Fault Length

Average :21 km Mostly :<= 45 km

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Behavioral Segments- Slip per Event

■ Paleoseimological data from 54 segments

Maximum : 9 m/event

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Fault Length v.s. Slip per Event

Dave = 1.2 x 10E-4 L ca.60% of Dmax

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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

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Scaling Laws for B & E-Segments

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Scaling Laws for B & E-Segments

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Scaling Laws for E & B-Segments

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Scaling law for Behavioral Segment

• 1891 to 2000

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Scaling law for Behavioral Segment

• 1931 Fuyun CH• 1995 Sakhalin RU• 1999 Chi-Chi TW• 2005 Kashmir RK

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Scaling law for Behavioral Segment

• B & R Province (dePolo et al.,

1991)

• 1992 Landers

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Scaling law for Behavioral Segment

• 1943 Bolu• 1999 Izmit• 1999 Duzce

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Scaling law for Behavioral Segment

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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

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Hierarchy ofsegment boundaries and

large earthquakes

Koji

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20th century segmentation

ONLY Segmented faulting as a FACT

NOT an idea, NOT a model

Need and worthwhile testing

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Repeated? NO!

Based on Ambraseys and Finkel (1995), --most rupture zones are not defined.

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Stationary

?

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Characteristic?Quasi-periodic?

Predictable?

Cascade?

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Bolu-Mudrnu

1943--1944

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Sub-characteristic or sub-A type earthquakes

Characterize ‘HARD’ segment boundary ZONE