Statistical Analysis of Building Damage in Japan based on the 2016 Kumamoto Earthquake

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Wesley Miles
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1 17th U.S.-Japan-New Zealand Workshop on the Improvement of Structural Engineering and Resilience Queenstown, New Zealand Statistical Analysis of Building Damage in Japan based on the 2016 Kumamoto Earthquake November 14, 2018 Fumio Yamazaki 1), Takuya Suto 1), Masashi Matsuoka 2), Kei Horie 3), Munenari Inoguchi 4), Wen Liu 1) 1) Chiba University, Chiba, Japan. 2) Tokyo Institute of Technology, Yokohama, Japan. 3) MS&AD InterRisk Research & Consulting, Inc., Tokyo, Japan. 4) Toyama University, Toyama, Japan. 1

2 Earthquake Damage Assessment Flow Inventory Data of Buildings & Infrastructures Fragility Curve Subsurface Soil Data 中央防災会議 Base Rock Motion Damage Distribution 2

3 Building damage in Mashiki Town April 16 3

4 Background Empirical fragility curves developed from the 1995 Kobe earthquake have been widely used in Japan. But 23 years have passed since the event. Significant building damages were caused in the April 2016 Kumamoto earthquake, and the Mashiki Town Government carried out the unified damage assessment for all the buildings in the town. Objective of the Research To analyze the building damage data in Mashiki Town compiled by the town government To develop fragility curves considering the structural material and construction period 4

5 Shake maps of the two Kumamoto events 2016/04/14 21:35 M w 6.2 (M J 6.5) JMA Instrumental Intensity 2016/04/16 01:25 M w 7.0 (M J 7.3) 5

Kumamoto 75 cm GEONET Choyo Kumamoto City M W 7.

6 Causative faults and GNSS stations in the 2016 Kumamoto earthquake 44 cm GEONET Kikuchi GEONET Kumamoto GEONET Kumamoto 75 cm GEONET Choyo Kumamoto City M W 7.0 Mashiki Town M W 6.2 Futagawa fault 97 cm GEONET Jonan Hinagu fault 25 cm M W 6.0 6

7 Result of damage (loss) assessment by Mashiki Town Gov. (2017) No damage (158) Minor (4325) Moderate (2442) Moderate + (791) Major (3026) 7

8 Building damage in the central Mashiki by the town government No damage (158) Minor (4325) Moderate (2442) Moderate + (791) Major (3026) 無被害一部損壊半壊大規模半壊全壊 8

9 Result of field survey by BRI and AIJ Kyushu branch based on Damage Grade of Okada & Takai (2000) Total 2340 無被害一部損壊一部損壊半壊全壊全壊倒壊全壊倒壊 9

Earthquake loss evaluation class of buildings in Japan and schematic images of

(Loss) Class Loss Ratio (r), Damage Index Major Major r > 60% EMS-98 Okada &

< r < 50% 20% < r < 40% G2 D2 Minor Minor 0% < r < 20% G1 D1 No No r = 0% (G0)

of damage classifications of buildings in the central Mashiki Town AIJ s

D0 D1 D2 D3 D4 D5 D6 Total No damage 1 0 0 0 0 0 0 1 Minor 175 91 13 3 1 0 0

10 Earthquake loss evaluation class of buildings in Japan and schematic images of other damage classification methods Current Damage (Loss) Class Former Damage (Loss) Class Loss Ratio (r), Damage Index Major Major r > 60% EMS-98 Okada & Takai (2000) G4 G5 D4, D5 Moderate + Moderate Moderate 50% < r < 60% G3 D3 40% < r < 50% 20% < r < 40% G2 D2 Minor Minor 0% < r < 20% G1 D1 No No r = 0% (G0) D0 Assuming the Loss Ratio (r) and the Damage Index (DI) are equal Comparison of damage classifications of buildings in the central Mashiki Town AIJ s survey Mashiki Town Gov. D0 D1 D2 D3 D4 D5 D6 Total No damage Minor Moderate Moderate Major Total

11 Damage classification of buildings by local governments with respect to the structural type Damage ratio Major Moderate+ Moderate 髛 Minor No damage 8, , % 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% , , ,244 2, , , Wooden RC S LS CB Total 100% 90% 80% Damage ratio 70% 60% 50% 40% 30% 20% 10% 0% Major Moderate Minor/No damage 22,710 3,814 2,173 1, ,544 5,997 11,293 1,179 4,806 2, , , ,198 Wooden RC S LS Others Total (a) Mashiki Town in 2016 Kumamoto EQ (b) Nada Ward in 1995 Kobe EQ Murao & Yamazaki (1999) 11

12 Revision of building s seismic code in Japan Building Standard Law 1950 Damage Ratio 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1960 Modification Old code New seismic code of the old code Tokachi-Oki EQ (1968) Miyagiken-Oki EQ (1978) Construction Period Others Moderate Severe 2000 Kobe EQ (1995) Modification of the new code Niigata-Chuetsu-Oki EQ (2007) 2010 Tohoku EQ (2011) Damage ratio of RC buildings in Nada Ward classified by construction period Murao & Yamazaki (1999) 12

13 Damage classification of wooden buildings in Mashiki Town with respect to construction period and construction year Damage ratio Damage ratio 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Major Moderate+ Moderate 髛 Minor No damage ,864 1,580 1,931 1, , Unknown Construction period Major Moderate+ Moderate 髛 Minor No damage 0% Construction year the nuumber of building 13

14 Compares the major damage ratio class for wooden buildings with respect to the construction period for four different datasets in Japan Major damage ratio Nishinomiya 1995 Nada 1995 Kashiwazaki 2007 Mashiki 2016 Construction Period 14

15 Estimated peak ground velocity (PGV) distribution and site amplification ratio in a 250-m grid in Mashiki Town PGV (cm/s) PGV Amplification Ratio 15

16 Major damage ratio (S axis) Development of fragility curves for Wooden, S and LS buildings 100% 90% Wooden 80% S Mashiki 70% LS 60% 50% 40% 30% 20% 10% 0% PGV(cm/s) Major damage ratio ln (PGV) MAJOR DAMAGE RATIO 100% 80% 60% 40% 20% 0% Wooden (Nishinomiya City) 1995 Kobe EQ Wooden (Nada Ward) 1995 Kobe EQ Wooden (Mashiki Town) 2016 Kumamoto EQ PGV(CM/S) 16

17 Development of fragility curves for wooden buildings in Mashiki town with respect to the construction period Major damage Damage ratio 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Major damage ratio 100% 80% 60% 40% 20% (Nishinomiya City ) (Nada Ward) (Mashiki Town) 0% PGV(cm/s) 0% PGV(cm/s) 17

18 Conclusions Building damage data surveyed by Mashiki Town Government were analyzed with respect to the structural material and construction period. The damage ratios of buildings in Mashiki Town were similar levels with those in Nada Ward due the 1995 Kobe earthquake. Fragility curves were developed for wooden buildings for different construction periods corresponding the revisions of seismic code in Japan. The developed curves are recommended to use for damage assessment of future earthquakes in Japan. 18

19 Thank you very much! 19

COMPARATIVE STUDY ON WOODEN HOUSE DAMAGE BETWEEN 1995 KOBE EQRTHQUAKE AND 2000 TOTTORI EARTHQUAKE OF JAPAN

3 th World Conference on Earthquake Engineering Vancouver, B.C., Canada August -6, 24 Paper No. 255 COMPARATIVE STUDY ON WOODEN HOUSE DAMAGE BETWEEN 995 KOBE EQRTHQUAKE AND 2 TOTTORI EARTHQUAKE OF JAPAN