Overview of Active Fault Research at Geological Survey of...
Transcript of Overview of Active Fault Research at Geological Survey of...
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Overview of Active Fault Researchat Geological Survey of Japan
Yasuo. AWATA and Toshikazu. YOSHIOKA
Active Fault Research Center,Geological Survey of Japan, AIST
UJNR, November 10, 2006, Tokushima
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Main Subjects on Active Fault Research
Paleoseismological investigation
Segmentation and scaling relations
Prediction of earthquake magnitude
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Paleoseismological Investigation
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Active Fault Research Project in Japan, 1st Stage
■1995 to 2004 FY
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Active Fault Research Project in Japan, 1st Stage
■1995 to 2004 FY■98 Active fault regions■ Investigated mainly by
local govern. and GSJ■Evaluated by ERC, HERP
by local governmentsby GSJ
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Probabilistic Shaking Map for Coming 30 Years( ERC, 2005 )
Active faultsSubduction boundary
Other sources
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Active Fault Research Project in Japan, 2nd Stage
■From 2005 FY
■18 faults re-investigated by GSJ, in 2005 - 2006
40 fault regions will bere-investigated
Improved segmentation and scaling relations will be used ?
by Local Govern.by GSJby GSJ’s budget
(from 2003)contract with MEXT
(2005 and 2006)
Nagamachi-Rifu F
Itoigawa-Shizuoka F
Tachikawa F
Kego F
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Paleoseismicty of an Active Fault, Which Triggered during the 2004 Mid-Niigata Earthq.
Triggered surface rupture, with a slip of 0.2 m
Characteristic two faulting eventseach with a slip > 1.5 m
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Prediction of “Most-Likely Earthquake-Segment”by ERC
5-km-thresould (Matsuda, 1990)Scaling relation between total rupture length and slip145 :Most likely earthquake segments12 :further segmented based on paloseismicity alone
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Fault Segmentationand
New Scaling Relations
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Behavioral Segment & Earthquake Segment
Time
Estimate the extent of behavior segment ?Probabilistic prediction of earthquake segment ?
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Segmentation of 15 Surface Ruptures in Japan
Paleoseismicity, Rupture process, GeometrySegment length <= 35 kmJog and Gap >= 2 km
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Scaling Relation : for Behavioral Segments
13 segments / in 6 ruptures
y = 0.1965xR2 = 0.905
0
5
10
15
0 20 40 60 80
Behavioral Segment Length (km)
strike-slip
Dmax =
2.0 x
10e-4
L
Japan (strike-slip)
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Scaling Relation : for Behavioral Segments
y = 0.169x
y = 0.2047xy = 0.2028x
0
5
10
15
0 20 40 60 80
Behavioral Segment Length (km)
strike-slipreversenormal
World (all types)
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Scaling Relation : for Behavioral Segments
y = 0.1965xR2 = 0.905
0
5
10
15
0 20 40 60 80
Behavioral Segment Length (km)
strike-slip
y = 0.169x
y = 0.2047xy = 0.2028x
0
5
10
15
0 20 40 60 80
Behavioral Segment Length (km)
strike-slipreversenormal
Dmax =
2.0 x
10e-4
L
Japan (strike-slip) World (all types)
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Criteria for Behavioral Segment
Geometry :Jog & Gap >= 2 km :Bend >=20 deg.
Paleoseismicity :Timing of faulting event:Recurrence interval
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Behavioral Segments - Fault Length
km431 behavioral segments
( Length >= 10 km ) ( Slip rate >= 0.1 mm/y )
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Behavioral Segments - Fault Length
431 behavioral segments ( Length >= 10 km ) ( Slip rate >= 0.1 mm/y )
145 prob. earthq. segments.(by ERC, 2005)
290 behavioral segments
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Behavioral Segments - Fault Length
Mostly <= 40 km
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Fault Length v.s. Slip per Event
Dave. = 1.2 x 10e-4 L = ~ 0.6 Dmax
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Prediction ofFuture Earthquake Segments
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Prediction of Most Likely Earthquake Segments
Application of 5-km-thresould ( Matsuda, 1990 )
431 b-segments → 256 earthquake-segments
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Scaling Relation : Between B- & E-Segments
Predicted
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Scaling Relation : Between B- & E-Segments
Predicted
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Scaling Relation : Between B- & E-Segments
Predicted
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Scaling Relation : for Historical RupturesTotal Length v.s. Maximum Slip
0
2
4
6
8
10
12
14
0 100 200 300 400 500
Total Length of Surface Rupture (km)
Data from Wells & Coppersmith(1994) and others after 1994
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Summary
We have been contributingto the Paleoseismological investigation.
We are workingon fault segmentation and new scaling relations
We have to attack to the problemson the probabilistic prediction of future earthquakes
( geology, mechanics of earthquake & faulting )
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“Active Fault Database” at AFRC Website( http://www.aist.go.jp/RIODB/activefault/ )
500 segmentswith fault strand mapParameters of faultingSite information on long-term slip rate and paleoseismicity
Tokushima●
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“Active Fault Database” at AFRC Website( http://www.aist.go.jp/RIODB/activefault/ )
Segmentation of MTLStrike N 80 EDip 45 NLength 52 kmSense of Faulting Right-lateral Upthrown Side North-sideSlip Rate 4 m/kySlip per Event 6.9 mRecurrence Interval 1.7 ky
AD 1500 to 1868 Age of Last FaultingAD 1596 (documented)
Elapsed-time Rate 0.18ca. 0 % by BPTRupture Probability
in Next 30 years ca. 2 % by Poisson
Chichio Segment
Tokushima●
302005 Kashmir Earthquake, PAK
Thank You for Your Attention