Sloshing Damage to Oil Storage Tanks
due to Long-Period Strong Ground Motions
during the 2011 Tohoku, Japan Earthquake

Ken Hatayama
National Research Institute of Fire and Disaster (ＮＲＩＦＤ)
Fire and Disaster Management Agency (FDMA)

Overview of Tsunami Damage to Oil Tanks during 3.11
- Largest-scale oil tank disaster due to a tsunami worldwide ever.
- Totally 417 oil tanks damaged.
- 157 oil tanks washed away, drifted away, slid, floated, or tipped.
- Several tanks burned in a spreading fire caused by the tsunami.

Kesen’numa, Miyagi

Sendai, Miyagi

1Strong Ground Motion Distribution Observed during 3.11
Short Periods (1 to 15 Hz)

Long Periods (5 to 15 s)☆ Petroleum
Industrial
ComplexSpectral Acceleration

Pseudo Spectral Velocity☆ Petroleum
Industrial
Complex

Kurahashi & Irikura(2013)

Natural Period (s)Natural Period of Liquid Sloshing of Large Tanks

1st Mode

2nd Mode

5,300
kilo‐gallon

Tank Capacity (kL)

37,000kilo‐gallon[Yamauchi(2006)]

2

Strong Ground Motion Distribution Observed during 3.11
Short Periods (1 to 15 Hz)

Pseudo Spectral Velocity

Spectral Acceleration☆ Petroleum
Industrial
Complex(PIC)Long Periods (5 to 15 s)☆ Petroleum
IndustrialComplex(PIC)

Overview of Ground Motion Damage
to Oil Tanks during 3.11
■ Damage by Short-Period (1-15 Hz) Ground Motion- No damage directly caused by short-period strong ground motions.
- Some oil tanks damaged due to deformation of the foundation groundcaused by liquefaction.

■ Damage by Long-Period (3-15 s) Ground Motion- Severe sloshing damage (sinking of the floating roof & complete collapseof the internal floating roof) to 2 tanks;- Quasi-severe damage to 21 tanks.
- No tank fire caused by sloshing.
- Less serious disaster than that of the 2003 Tokachi-oki eq. (Mw8.0).

3Outline Sloshing Damage to Oil Tanks due to Long-Period
Ground Motion (LPGM) during 3.11
 Comparison of Sloshing Damage between 2011
Mw9.0 Tohoku Eq. & 2003 Mw8.0 Tokachi-oki Eq.
 Implication for LPGM Microzoning from Observed
Spatial Variation of Sloshing Amplitudes

Sloshing Damage
in 2011 Mw9.0
Tohoku Eq.

4Roof Types of Oil Tanks

Floating Roof Type

Fixed Roof TypeInternal Floating
Roof Type

Schematic of
Floating Roof Tank

Observed Sloshing Amplitude at Oil Tanks
2011 Mw9.0

2003 Mw8.0 Tokachi-oki

5

Sloshing Amplitude: 2011 Tohoku (Mw9.0) & 2003 Tokachioki (Mw8.0)

Sloshing Damage in Niigata during 3.11

2011

Smear of crude oil

Oil spill onto the floating roof

Deformation of the gauge pole (Wh~1.4 m)

Infiltration of oil into pontoons (Wh~1.9 m)

6

Sloshing Damage during 3.11:
Running-off of the rolling ladder in Sendai

Severe Sloshing Damage during 3.11:
Sinking of the floating roof in Kawasaki

2011

2011

Heavy Oil
CL = 20,000 kL
D = 38.7 m
HLmax = 16.4 m
HL = 8.9 m
Ts = 7.8 sηmax(obs) = 1 ~ 1.5 m
ηmax(cal) = 1.3 m[Image taken by Dr. Haruki Nishi]

7Severe Damage during 3.11: Complete collapseof the internal floating roof in Sakata

2011

Gasoline
CL = 2,700 kL
D = 15.5 m
HT = 16.7 m
HL = 9.3 m
Ts = 4.2 sηmax(cal) = 2.0 m
Fractured deck skin and float tube

Fractured float tube
Schematic of Internal Floating Roof[Image taken by Dr. Haruki Nishi]

Comparison ofSloshing Damage
between 2011 Mw9.0& 2003 Mw8.0 Tokachioki Eq.

8Severe Sloshing Damage to Tanks: 2011 & 2003

2003

Damage during the 2003 Tokachi-oki Eq.

2011 Tohoku(Mw9.0)FireSinking of floating roofs
Complete collapseof internal floating roofs

02003 Tokachi-oki(Mw8.0)

2 Tomakomai

1

Kawasaki

7 Tomakomai

1

Sakata1 Ishikari

Why Less Serious Sloshing Disaster in 2011 than in 2003?

1. Long Period Ground Motion
2. Oil Tank Distribution
3. Countermeasures in Seismic Codes of the Fire
Service Act taken after the 2003 Tokachi-okiearthquake

9Why the Open-Top Fire Occurred in 2003?

ignition

Open-Top Fire- Occurred 2 days later.
- Lasted for 2 days.

Sinking of the Floating Roof
Oil Surface Exposed to the Atmosphere

Preventing sinking of the floating roof is important for fire prevention.

Legally-require pontoons ensure resistance against oscillation of
the floating roof in the areas where large LPGM is predicted (by2017).

Why the Ring Fire Occurred in 2003?

Floating Roof
Hit Something
above the Top Angle
during Sloshing

Spark

Lowering the oil level at tanks should prevent tank fires and spill-out of oil.

10Raise the seismic design spectra against sloshing of oil tanks.
After 2003 Mw8.0

地域１－ロ
Tokyo Bay
Area

300

200

100300
速度応答スペクトル(cm/s)
Spectral
Velocity (cm/s)

300

Spectral
Velocity (cm/s)
速度応答スペクトル(cm/s)

Spectral
Velocity (cm/s)
速度応答スペクトル(cm/s)

Ishikari, Kamiiso, Akita,
Shimizu, Kinuura, Nagoya,
地域１－ハ
Yokkaichi,& Osaka Bay Area

Before 2003 Mw8.0

地域１－イ
Tomakomai,
Sakata, & Niigata

200

1000005101520周期(sec)Period(s)200100005101520周期(sec)Period(s)05101520周期(sec)Period(s)Legally-require to lower the oillevel at tanks in the areas
where large LPGM ispredicted (completed).

Observed Long-Period Ground Motion: 2011 & 20032011 Tohoku (Mw9.0)

2003 Tokachi-oki (Mw8.0)☆ Petroleum
IndustrialComplex(PIC)☆ Petroleum
IndustrialComplex(PIC)

Morikawa et al.(2006)

5 to 15 s

5 to 15 s

11Observed Long-Period Ground Motion: 2011 & 2003

2011

Sakata- The largest LPGM observed at Sakata.
- Comparable level to the 2003 Tomakomai.
- No floating roof tank located in Sakata.
- Only one internal floating roof tank placed in Sakata.
- This tank’s roof collapsed completely.

Niigata

2011- Niigata W. Port exceeding the design spectrum before the post-2003 revision.
- If the design spectrum had not been raised, oil might have spilt out of the tanks.

12

Tokyo Bay Area2011

- Observations fall below the design spectrum before the post-2003 revision.
- The reason of the sinking of floating roof is not understandable.

Observed Long-Period Ground Motion: 2011 & 2003

2011

Pacific Coast of Tohoku & Kanto

Observations basicallyfall below the design.

13Implication for
LPGM Microzoning fromObs. Sloshing Heights

Spatial Variation of Sloshing Heights within Short Distances→ Suggesting Significant Spatial Variation of LPGM within Short Distances?
Sloshing Wave Hight at Shibata

Niigata District

250240200150220

Niigata‐EEast200WestNiigata‐WWh(cm)180

Wh‐CAL(cm)160100Niigata‐EEast50

Niigata‐WWest

Natural Period~11s
678910Ts(sec)11121314Observed Sloshing Heights

1201008005140

1560402000

Niigata East Port

Seismometer
Installed in 2005

20 40 60 80 100 120 140 160 180 200 220 240
Wh‐OBS(cm)Comparison of Observed Sloshing Heights
with Sloshing Heights Calculated
from the 2011 Niigata-E Seismogram
If W. District LPGM is 50% larger than E. District,the observed sloshing amplitudes in W. District
will be reproduced.

[Zama (2013)]

14

E. District vs. W. District: Aftershocks Mw5.8 ~ 7.3
Niigata East Port

Seismometer
Installed in 2005

Seismometer
Installed in 2012

West / East

10 ~11sμ+σμ-σWest is 10 – 30% larger than East ON AVERAGE.
→ Consistent with the observed sloshing amplitudes.

Spatial Variation of Observed Sloshing Amplitudes~ Tomakomai during the 2003 Tokachi-oki ~Natural Period~10s[ Kaita (2004)]

15

Obs. vs. Cal.: PGV (Period: 6.5 – 15 s)
PGV Spatial Variation

Cal. agrees wellwith Obs.!

Vs > 3 km/s

The bedrock depth is NOT consistent with the observed
long‐period PGV.

Characteristics in the Shallow PartTHICK
soft
sediment
beneaththe Refinery

THIN
soft
sediment
in the East

16

Summary
Less serious sloshing disaster was observed in the 2011 Mw9.0 event than in the2003 Mw8.0 event: no sloshing-induced tank fire, severe damage to 2 tanks(sinking of the floating roof & complete collapse of internal floating roof).
This is basically because of :(1) Smaller Long-Period Ground Motions (LPGM) observed at Petroleum Industrial
Complexes (PIC) in 2011 than 2003;(2) No floating roof tank at Sakata PIC where comparable LPGM to the largest of
2003 (Tomakomai) was observed;(3) Legally-required countermeasures taken after the 2003 event.
 A significant spatial variation in long-period (11 s) GM levels (10 to 30%) and theconsequent sloshing (50%) at oil tanks was observed within short distances (2km), repeatedly suggesting the necessity of MICROZONING of LPGM for RISKREDUCTION.

Correction in your Handout!
2003 Tokachi-oki

2003 Tohoku(Mw8.0)(Mw9.0)17