Overview of Active Fault Research at Geological Survey of Japan Yasuo. AWATA and Toshikazu. YOSHIOKA Active Fault Research Center, Geological Survey of Japan, AIST UJNR, November 10, 2006, Tokushima 1
Main Subjects on Active Fault Research Paleoseismological investigation Segmentation and scaling relations Prediction of earthquake magnitude 2
Paleoseismological Investigation 3
Active Fault Research Project in Japan, 1st Stage 1995 to 2004 FY 4
Active Fault Research Project in Japan, 1st Stage by local governments by GSJ 1995 to 2004 FY 98 Active fault regions Investigated mainly by local govern. and GSJ Evaluated by ERC, HERP 5
Probabilistic Shaking Map for Coming 30 Years ( ERC, 2005 ) Active faults Subduction boundary Other sources 6
Active Fault Research Project in Japan, 2nd Stage by Local Govern. by GSJ s budget by GSJ (from 2003) contract with MEXT (2005 and 2006) Itoigawa-Shizuoka F From 2005 FY 18 faults re-investigated by GSJ, in 2005-2006 Kego F Tachikawa F Nagamachi-Rifu F 40 fault regions will be re-investigated Improved segmentation and scaling relations will be used? 7
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 events each with a slip > 1.5 m 8
Prediction of Most-Likely Earthquake-Segment by ERC 5-km-thresould (Matsuda, 1990) Scaling relation between total rupture length and slip 145 :Most likely earthquake segments 12 :further segmented based on paloseismicity alone 9
Fault Segmentation and New Scaling Relations 10
Behavioral Segment & Earthquake Segment Time Estimate the extent of behavior segment? Probabilistic prediction of earthquake segment? 11
Segmentation of 15 Surface Ruptures in Japan Paleoseismicity, Rupture process, Geometry Segment length <= 35 km Jog and Gap >= 2 km 12
Scaling Relation : for Behavioral Segments 15 10 strike-slip Dmax = 2.0 x 10e-4 L y = 0.1965x R 2 = 0.905 13 segments / in 6 ruptures 5 0 0 20 40 60 80 Behavioral Segment Length (km) Japan (strike-slip) 13
Scaling Relation : for Behavioral Segments 15 strike-slip reverse normal y = 0.2047x y = 0.2028x 10 y = 0.169x 5 0 0 20 40 60 80 Behavioral Segment Length (km) World (all types) 14
Scaling Relation : for Behavioral Segments 15 10 strike-slip Dmax = 2.0 x 10e-4 L y = 0.1965x R 2 = 0.905 15 10 strike-slip reverse normal y = 0.2047x y = 0.2028x y = 0.169x 5 5 0 0 20 40 60 80 0 0 20 40 60 80 Behavioral Segment Length (km) Behavioral Segment Length (km) Japan (strike-slip) World (all types) 15
Criteria for Behavioral Segment Geometry :Jog & Gap >= 2 km :Bend >=20 deg. Paleoseismicity :Timing of faulting event :Recurrence interval 16
Behavioral Segments - Fault Length 431 behavioral segments ( Length >= 10 km ) ( Slip rate >= 0.1 mm/y ) km 17
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 18
Behavioral Segments - Fault Length Mostly <= 40 km 19
Fault Length v.s. Slip per Event Dave. = 1.2 x 10e-4 L = ~ 0.6 Dmax 20
Prediction of Future Earthquake Segments 21
Prediction of Most Likely Earthquake Segments Application of 5-km-thresould ( Matsuda, 1990 ) 431 b-segments 256 earthquake-segments 22
Scaling Relation : Between B- & E-Segments Predicted 23
Scaling Relation : Between B- & E-Segments Predicted 24
Scaling Relation : Between B- & E-Segments Predicted 25
Scaling Relation : for Historical Ruptures Total Length v.s. Maximum Slip 14 12 10 8 6 4 2 0 0 100 200 300 400 500 Total Length of Surface Rupture (km) Data from Wells & Coppersmith(1994) and others after 1994 26
Summary We have been contributing to the Paleoseismological investigation. We are working on fault segmentation and new scaling relations We have to attack to the problems on the probabilistic prediction of future earthquakes ( geology, mechanics of earthquake & faulting ) 27
Active Fault Database at AFRC Website ( http://www.aist.go.jp/riodb/activefault/ ) 500 segments with fault strand map Parameters of faulting Site information on long-term slip rate and paleoseismicity Tokushima 28
Active Fault Database at AFRC Website ( http://www.aist.go.jp/riodb/activefault/ ) Chichio Segment Strike N 80 E Segmentation of MTL Dip 45 N Length 52 km Sense of Faulting Right-lateral Upthrown Side North-side Slip Rate 4 m/ky Slip per Event 6.9 m Recurrence Interval 1.7 ky Age of Last Faulting AD 1500 to 1868 AD 1596 (documented) Elapsed-time Rate 0.18 Rupture Probability ca. 0 % by BPT in Next 30 years ca. 2 % by Poisson Tokushima 29
Thank You for Your Attention 30 2005 Kashmir Earthquake, PAK