Ground motions and Structural Responses caused by the Great Tohoku-Kanto Earthquake, March 11, 2011

Dionysius Siringoringodion@bridge.t.u-tokyo.ac.jp

Bridge & StructureUniv. of Tokyo

2011 Great Tohoku-Kanto EarthquakeMagnitude : Mw 9.0 (JMA)Date : March 11, 2011

Trigger time : 14:46 JST

Epicenter Depth : 24 km (JMA), 32km (USGS)

Location : 38.103°N, 142.860°E (JMA, as of 2011-03-13)

Region : on the pacific coast along from Sanriku to Ibaraki coast,Japan

Fourth largest in the world since 1900, and the largest in Japan since modern instrumentation recordings began 130 years ago.

World’s largest earthquake

Sumatra 2004 (Mw9.0)

Chile 1960 (Mw9.5)

Chile 2010 (Mw8.8)

Alaska 1964 (Mw9.2)

Andreanov 1957 (Mw9.1)

Kamchatka 1957 (Mw9.0)

Tohoku Kanto 2011 (Mw9.0)

Source : Earthquake research institute (ERI Univ of Tokyo)

Casualty : Confirmed Death 11,620, unaccounted for 16,464 (until April 1, 2011)

Source: Geospatial Information Authority of Japan, http://www.gsi.go.jp/cais/topic110315-index-e.html

Vertical Deformation and Slip Distribution from model (prelimiary results) (Geospatial Information Authority of Japan)

source : Japan Meteorology Agency (JMA)Note: in some areas intensity are updated later on to larger value.

Observed JMA Seismic Intensity distribution

Tsunami Warning Issued right after the earthquake by JMA

Maximum Height of Tsunami, Measured and Simulated by Model (Yushiro Fujii (IISEE, BRI) and Kenji Satake (ERI, Univ. of Tokyo))

Solid lines in red and blue indicate the observed tsunami waveform and syntetic ones, respectivelySource: http://iisee.kenken.go.jp/staff/fujii/OffTohokuPacific2011/tsunami.html

Station Location Code Provider

Distance (km) PGA (xG)Horizontal

GroundmotionTo epicenter To Fault

TSUKIDATE  MYG004 KNET 125.9 75.1 2.755SHIOGAMA  MYG012 KNET 118.1 67.4 2.009

HITACHI  IBR003 KNET 245.2 58.7 1.631SENDAI  MYG013 KNET 126.1 71.8 1.548HOKOTA  IBR013 KNET 292.3 77.8 1.383MOTEGI  TCG014 KNET 276.8 87.7 1.23

HAGA  TCGH16 KIKNET 283 95.1 1.221NISHIGOU  FKSH10 KIKNET 238 106.3 1.084

OSHIKA  MYG011 KNET 75.7 49.7 0.94YAMAMOTO  MYGH10 KIKNET 136 67.9 0.889

MIYAKOJI  FKSH19 KIKNET 173 69.1 0.874BATOU  TCGH13 KIKNET 262 90.2 0.857

IWASE  IBRH11 KIKNET 293 91.8 0.844MITO  IBR006 KNET 275.3 70.8 0.802

GOZENYAMA  IBRH15 KIKNET 268 78.7 0.797

TOHWA  MYG003 KNET 103 59.2 0.797RIKUZENTAKATA  IWTH27 KIKNET 107 54.3 0.753

KAMAISHI  IWT007 KNET 114.3 49 0.711

UTATSU  MYG002 KNET 87.2 52.1 0.671

SOHMA*  FKS001 KNET 140 63.8 0.632

* SOHMA is located about 43 km from Fukushima Daiichi Power plant

List of Ground Motions with largest Horizontal Peak Acceleration (Data provided by K-Net and Kik-Net Service)

MYG: Miyagi prefecture, IBR/IBRH: Ibaraki, TCG: Tochigi, FKS/FKSH: Fukushima, IWT: Iwate

Taneichi

Kamaishi

Tsukidate

Shiogama

Sendai

Soma

Hitachi

Characteristics of ground motions (E-W)

Fault plane

Taneichi

Kamaishi

Tsukidate

Shiogama

Sendai

Soma

Hitachi

Characteristics of ground motions (N-S)

Fault plane

• Ground motions near the source display two remarkable phases of mainshock suggesting the existence of a least two areas of large slip.

• In the northern part of the source area the first phase is predominant, while in the southern part and in Kanto region, this phase is not visible.

• These two phases of ground motion suggest large slip areas in the North and South regions respectively.

Characteristics of ground motions (NIED preliminary report)

50 100 150 200 250 300-1000

0

1000

Time(s)

Acc

(cm

/s2 )

MYG004-EW

50 100 150 200 250 300

-2000

0

2000

Time(s)

Acc

(cm

/s2 )

MYG004-NS

0 50 100 150 200 250 300-2000

0

2000

Time(s)

Acc

(cm

/s2 )

MYG004-UD

Max =1.25 G

Max =2.75 G

Max =1.8 G

Records with largest PGA : Tsukidate Station, Miyagi. Distance to epicenter : 125.9 Km, Distance to Fault 75Km (K-NET)

Tohoku-Kanto 2011 Magnitude 9

Tsukidate Station, PGA = 2.75G(Seismic intensity 6.67 )

Hyogo-ken Nanbu earthquake (Kobe 1995) Magnitude 7.2 Kobe-JMA station , PGA=0.82GSeismic intensity 7

Two main shock events last for 2 minutes

One main shock event lasts for about 30 seconds

One main shock event lasts for about 20 seconds

Niigata-Chuetsu Earthquake (Oct 23, 2004) Magnitude 6.8 Ojiya station, PGA=1.33G Seismic intensity 7

Comparisons with the Kobe 1995 and Niigata Chuetsu 2004 Earthquakes

Acceleration amplitude and duration of shaking, this earthquake is much larger than Kobe 1995.

Records from Soma City about 43km from Fukushima Power Plant. Distance to epicenter 140km, distance to the fault 63 km (K-NET)

Reactor was designed to sustain maximum PGA 440 gals. TEPCO has planned to reinforce the reactors so they could withstand horizontal shaking of 600 gals, after the government reviewed their quake-resistance standards 5 years ago. But the work was not finished.Source: NHK-TEPCO (http://www3.nhk.or.jp/daily/english/01_39.html)

Acceleration Response Spectra for several large ground motions and comparison with the current Japanese code

Ground motion Type I is for plate boundary type large-scale earthquake

Ground motion Type II is for inland direct strike type earthquake, such as the Hyogo-ken Nanbu Earthquake (Kobe 1995) ,

Class (e.g.I and III) is divided according to ground condition, and the ones depicted on figure are the maximum for each type.

Accel amplitude for short period structure. are larger than the current code.

Ground motion Type I is for plate boundary type large-scale earthquake

Ground motion Type II is for inland direct strike type earthquake, such as the Hyogo-ken Nanbu Earthquake (Kobe 1995) ,

Class (e.g.I and III) is divided according to ground condition, and the ones depicted on figure are the maximum for each type.

Acceleration Response Spectra for several large ground motions and comparison with the current Japanese code

Accel amplitude for long period structures (highrise building, long-span bridge) are smaller than the current code.

Comparison of Tohoku-Kanto 2011 Response Spectrum to other recent large earthquake in Japan

Envelope of Kobe 1995 Spectra

Envelope of Tohoku-Kanto 2011 Spectra

Compared to Kobe 1995 earthquake, the Tohoku-Kanto 2011 spectra :

1.contains larger amplitude for short period oscillation (less than 0.5 sec or higher than 2Hz), but smaller amplitude for structure with longer period (larger than 0.5sec).2.Has the maximum PGA of almost 3 times the maximum PGA of Kobe 19953.has narrower range for large spectra amplitude (0.2 – 0.4 sec), while the Kobe spectra has a very wide range of large amplitude (0.2 – 2 sec).

Comparison with world’s well-known earthquakes

Station Location Code ProviderDistance (km) PGA (xG)

To epicenter To Fault Horizontal

Groundmotion Matsudo (Chiba) CHB002 KNET 356.7 136.1 0.290

Mizue (Tokyo) TKY027 KNET 365.7 143.4 0.216Shiohama (Tokyo) TKY020 KNET 372.6 150.4 0.147Sunamachi (Tokyo) TKY013 KNET 371.8 149.3 0.144Shinonome (Tokyo) TKY016 KNET 374.7 152.3 0.164

Urayasu (Chiba) CHB008 KNET 368.7 145.6 0.160Chiba City (Chiba) CHB009 KNET 362 138 0.183

Yokohama (Kanagawa) KNG002 KNET 402.4 178.1 0.168Kawaguchi (Saitama) SIT011 KNET 364.9 146.8 0.184

Ground motions recorded near Tokyo metropolitan area

Acceleration Response Spectra for several ground motions in Tokyo metropolitan area

Acceleration Response Spectra for several ground motions around Tokyo metropolitan area

Acceleration Response Spectra for several ground motions in and around Tokyo Metropolitan area and comparison with Building Code

Long Period Ground Motion Characteristics recorded in Tokyo metropolitan area

Long period shaking for about 1.5 minuteis a particular concern to high-rise buildings and long-span bridges

Long Period Ground Motion Characteristics recorded in Tokyo metropolitan area

Sunamachi (K-NET Data)

Dominated by Less than 1Hz vibration

Long Period Ground Motion Characteristics recorded in Tokyo metropolitan area

Shiohama (K-NET Data)

Long Period Ground Motion Characteristics recorded in Tokyo metropolitan area

Urayasu city (K-Net Data)

Displacement Response Estimation of High-rise Building in Tokyo area

Surveyed from 256 Buildings in Japan. (Miyakoshi & Horike 2008)

The responses of top floor due Tohoku-Kanto Earthquake is calculated using the following assumptions:

1.One story height is 3m. 2.Predominant Natural period of building follows the relationship: T= 0.023 H (height m)3.The building response can be modeled by SDOF response with predominant natural period as defined in (2)4.Structural system remains linear throughout the excitation5.Damping ratio 5%

Input Ground motion TKY013-EW

Response Estimation of High-rise Buildings in Tokyo area : Sunamachi

Intense shaking for about 2 minutes

Input Ground motion CHB008-EW

Response Estimation of High-rise Building in Tokyo area : Urayasu

Intense shaking for about 1.5-2 minutes

Input Ground motion TKY020-EW (KNEt Data)

Response Estimation of High-rise Building in Tokyo area : Shiohama

Intense shaking for about 1.5-2 minutes

Response Estimation of High-rise Building in Tokyo area : Hongo, Bunkyo-ku

Input Ground motion Univ. of Tokyo UTK (BRI Data)

Intense shaking for about 1.5 minutes

Drop in vibration frequency indicating the structural softening when the base isolation/sliding system starts to engage

Structural first frequency in small (linear) excitation

Measured response of a base-isolation 14-story building in Tokyo area

Measured girder response of a long-span cable-stayed bridge in Kanto area(midspan length : 460m)

Max vertical disp 19.5cm

Max transverse disp 61.8cm

Max long disp 24.5cm

DisclaimerUnless mentioned otherwise, charts, figures, and computations are

produced by author.Others are compiled from the following data source :

Seismographs network in Japan : K-Net Japan, KikNet, Building Research Institute Japan (BRI)Japan Meteorology Agency, Geospatial Information Agency of Japan, Earthquake Research Institute (ERI Univ of Tokyo), NHK, TEPCO

Tokyo 2011-04-0114:46

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2011-03-1114:46