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 Yamazaki1), Takuya Suto1), Masashi Matsuoka2), Kei Horie3), Munenari Inoguchi4), Wen Liu1) 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 Earthquake Damage Assessment Flow

Inventory Data of Buildings & Infrastructures

Fragility Curve

Subsurface Soil Data

中央防災会議 Damage Distribution Base Rock Motion 2 Building damage in Mashiki Town April 16

3 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 JMA Instrumental Shake maps of the two Kumamoto events Intensity 2016/04/14 21:35

Mw6.2 (MJ6.5)

2016/04/16 01:25

Mw7.0 (MJ7.3)

http://map03.ecom-plat.jp/map/map/?cid=20&gid=587&mid=2892 5 Causative faults and GNSS stations in the 2016 Kumamoto earthquake

44 cm GEONET Kikuchi

GEONET 75 cm GEONET GEONET Kumamoto Kumamoto Choyo

Mashiki Kumamoto Town 97 cm City Futagawa fault MW 7.0 MW 6.2

GEONET Jonan 25 cm MW 6.0 Hinagu fault

6 Result of damage (loss) assessment by Mashiki Town Gov. (2017)

No damage (158) Minor (4325) Moderate – (2442) Moderate + (791) Major (3026)

7 Building damage in the central Mashiki by the town government

No damage (158) 無被害 Minor (4325) 一部損壊 Moderate – (2442) 半壊 Moderate + (791) 大規模半壊 Major (3026) 全壊

8 Result of field survey by BRI and AIJ Kyushu branch based on Damage Grade of Okada & Takai (2000)

無被害 631 一部損壊 600 一部損壊 263 半壊 282 全壊 254 全壊・倒壊 236 全壊・倒壊 74 Total 2340

9 Earthquake loss evaluation class of buildings in Japan and schematic images of other damage classification methods Current Damage Former Damage Loss Ratio (r), EMS-98 Okada & Takai (Loss) Class (Loss) Class Damage Index (2000) G4 G5 D4 , D5 Major Major r > 60%

50% < r < 60% G3 D3

Moderate + 40% < r < 50% Moderate Moderate – 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 10000001 Minor 175 91 13 3 1 0 0 283 Moderate - 103 161 47 15 1 0 0 327 Moderate + 76132180 1 0119 Major 18 83 80 146 147 149 31 654 Total 304 396 172 182 149 150 31 1384 10 Damage classification of buildings by local governments with respect to the structural type

髛 Major Moderate+ Moderate Minor No damage Major Moderate Minor/No damage 736 8,972 113 332 6 10,159 22,710 3,814 1,301 546 30,544 100% 7 1 8 100% 2,173 90% 90% 3,080 2 5,997 80% 3,896 80% 11,293 70% 70% 1,179 324 214 511 865 60% 89 60% 4,806 2,928 2,244 50% 2,438 50% 6,053 40% 3 40% Damage Damage ratio Damage ratio Damage 801 462 30% 842 30% 89 55 11,907 164 20% 123 20% 13,198 20 532 2,840 13 19 2,975 532 133 10% 2 1 10% 272 9 43 82 354 0% 0% Wooden RC S LS CB Total Wooden RC S LS Others Total (a) Mashiki Town in 2016 Kumamoto EQ (b) Nada Ward in 1995 Kobe EQ

Murao & Yamazaki (1999)

11 Revision of building’s seismic code in Japan

Modification Building Modification Old code New seismic code Standard Law of the old code of the new code 1981 1970 71 80 90 2010 1950 1960 2000 Miyagiken-Oki EQ Kobe EQ (1995) Tokachi-Oki EQ (1978) (1968) Niigata-Chuetsu-Oki EQ (2007) Tohoku EQ (2011) 100% Others 90% Moderate 80% Severe 70% 60% 50% 40% Damage ratio of RC buildings in Nada Damage Ratio Damage 30% Ward classified by construction period 20% 10% 0% Murao & Yamazaki (1999) -1951 1952-61 1962-71 1972-81 1982-94 12 Construction Period Damage classification of wooden buildings in Mashiki Town with respect to construction period and construction year Major Moderate+ Moderate髛 Minor No damage 705 227 554 1,864 1,580 1,931 1,591 520 100% 1 122 1 75 16 65 90% 279 34 414 80% 92 170 111 902 70% 74 26 511 60% 60 1,159 551 121 50% 217 40% 568 50 464 151 187 30% 317 Damage Damage ratio 856 20% 140 256 178 428 10% 319 47 127 0% -1951 1952-61 1962-71 1972-81 1982-90 1991-2000 2001-16 Unknown Construction period Major Moderate+ Moderate髛 Minor No damage 100% 800 90% 700 80% 600 70% 60% 500 50% 400 40% 300 30% 200

Damage Damage ratio 20% 10% 100

0% 0 of building the nuumber -1951 1961 1971 1981 1991 2001 2011 Construction year 13 Compares the major damage ratio class for wooden buildings with respect to the construction period for four different datasets in Japan

1.00 Nishinomiya 1995 0.90 Nada 1995 0.80 Kashiwazaki 2007 0.70 Mashiki 2016 0.60 0.50 0.40 0.30 Major damage ratio Major damage 0.20 0.10 0.00

Construction Period

14 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 Development of fragility curves for Wooden, S and LS buildings

1.00 100% Wooden (Nishinomiya City) 1995 Kobe EQ 80% Wooden (Nada Ward) 0.00 1995 Kobe EQ 4.00 4.50 5.00 5.50 Wooden (Mashiki Town) 60% 2016 Kumamoto EQ -1.00 40%

-2.00 20% MAJOR DAMAGE RATIO DAMAGE MAJOR

-3.00 axis) (S ratio damage Major 0% ln (PGV) 0 20 40 60 80 100 120 140 160 180 200 PGV(CM/S) 100% 90% Wooden ■ 80% S ▲ Mashiki 70% LS ○ 60% 50% 40% 30% 20% 10% Major damage ratio damage Major 0% 0 20 40 60 80 100 120 140 160 180 200 220 240 PGV(cm/s) 16 Development of fragility curves for wooden buildings in Mashiki town with respect to the construction period

Major damage

100% 100% 1962-71 ● 90% （ 1972-81 □ 1982-94 Nishinomiya City 80% ） 1982-90 ○ 80% （ ） 70% 1991-2000 △ 1982-94 Nada Ward 60% 2001-16 ◆ 60% 1982-90（Mashiki Town） 50% 40% 40% Damage Damage ratio 30% 20% Major damage ratio Major damage 20% 10% 0% 0 20 40 60 80 100 120 140 160 180 200 220 240 0% 0 20 40 60 80 100 120 140 160 180 200 PGV(cm/s) PGV(cm/s)

17 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 Thank you very much!

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