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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