geotechnical lessons learned from the m7.0 2010 haiti...

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GEOTECHNICAL LESSONS LEARNED FROM THE M7.0 2010 HAITI EARTHQUAKE:

“WHY THE PALACE FELL”

Brady R. Cox, PhD, PE

The University of Arkansas

Presented at the 2012 EERI Annual Meeting and National Earthquake Conference

Memphis, TN; April 11, 2012

Razorbacks

Why the Palace Fell… Geotechnical Aspects

Geotechnical Lessons from the M7.0 Haiti Earthquake: Brady R. Cox, PhD, PE 2

http://www.newsweek.com/2010/01/20/why‐the‐palace‐fell.html

20

15

10

5

0

Dep

th (

ft)

150010005000

Shear Wave Velocity (ft/sec)

6

5

4

3

2

1

0

Depth (m

)

4003002001000

Shear Wave Velocity (m/s)

SASW-6 SASW-7 SASW-8

Cox, B.R., Bachhuber, J., Rathje, E., Wood, C.M., Dulberg, R., Kottke, A., Green, R.A., Olson, S. (2011). “Shear Wave Velocity‐ and Geology‐based Seismic Microzonation of Port‐au‐Prince, Haiti,” Earthquake Spectra, 27(S1), S67‐S92.

Rathje, E.M., Bachhuber, J., Dulberg, R., Cox, B.R., Kottke, A., Wood, C., Green, R.A., Olson, S., Wells, D., Rix, G. (2011). “Damage Patterns in Port‐au‐Prince from the 2010 Haiti Earthquake and their Relationship to Geologic Conditions,” Earthquake Spectra, 27(S1), S117‐S136.

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2010 Haiti EQ: GEER Team

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• Prof. Ellen Rathje (Team leader, University of Texas)• Mr. Jeff Bachhuber (Fugro/William Lettis & Associates)• Prof. Brady Cox (University of Arkansas)• Mr. Jim French (AMEC/Geomatrix)• Prof. Russell Green (Virginia Tech)• Mr. Juan Molina (Constructora Inmobiliaria M&N)• Mr. Tabare Mundaray (Proyectos Especiales)• Prof. Scott Olson (University of Illinois)• Prof. Luis Pena (Pontificia Universidad Catolica)• Prof. Glenn Rix (Georgia Tech)• Mr. Oscar Suncar (University of Texas)• Mr. Rick Sellars (AMEC/Geomatrix)• Mr. Donald Wells (AMEC/Geomatrix)


2010 M7.0 Haiti EQ: Casualties ~ 300,000 killed; ~ 1 million homeless

Haiti

Chile

Earthquake Magnitude

Fatalities per Earthquake

Tohoku

ChCh

(modified from Roger Bilham and Russell Green)


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Haiti Location Map

USA

S. America

Haiti


Haiti EQ Epicenter and Aftershocks (M > 4.0)

Mainshock = Mw 7.0; No visible surface fault rupture, some areas of coastal uplift (dip‐slip)


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UNOSAT Damage Survey Map: PaP

• Destroyed ( 9 - 12% )• Severe Damage ( 7 - 12% )• Moderate Damage ( 5 – 8% )

Cox GPS TracksInitial GEER Recon

Downtown/Presidential

Palace

Port


Port LiquefactionPre-EQ

Aug 2009Post-EQJan 2010

Wharf Deck

Pile-Supported

Pier

Crane


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Downtown/Presidential Palace Area


Back Home… Damage Patterns

“Earthquake-induced damage in Port-au-Prince was devastating and widespread. Yet, there were clearly areas of the city where little to no damage occurred, and areas of the city where an overwhelming majority of the buildings were severely damaged or destroyed.”

• Relative distance from fault rupture plane

• Construction type and quality

• Local soil conditions (i.e. strength/stiffness of foundationsoil, depth to bedrock, impedance contrasts, age/geology)

• Topography (topographic and basin effects)

• Near fault effects

Factors that Influence Damage Patterns for a Given EQ:

Virtually no information was available


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Available Regional Geologic Map of PaP

1:250,000 scale: C.E.R.C.G. IMAGEO Lambert, Gaudin and Cohen, 1987

Port-au-Prince Bay

Pliocene

Quaternary

Miocene


Geology – Topography Mismatch

DEM from LiDAR survey

funded by World Bank and

performed by RIT

Color-shade elevation

contours by CAST at UofA


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2nd Trip: NSF RAPID Proposal

RAPID: Geotechnical‐driven Damage Patterns and Liquefaction in the January 2010 Haiti Earthquake

• Prof. Scott Olson (PI; University of Illinois)• Prof. Brady Cox (Co‐PI; University of Arkansas)• Mr. Jeff Bachhuber (Fugro)• Prof. Russell Green (Virginia Tech)• Prof. Ellen Rathje (University of Texas)• Albert Kottke (GRA; UT)• Sam Lasley (GRA; VT)• Nate Martin (GRA; UI)• Clint Wood (GRA; UA)


36 MASW Testing Locations for Vs Profiles


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36 MASW Testing Locations for Vs Profiles


New Geologic Map of PaP

Jeff Bachhuber’s ‘baby’

Old Regional Map


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Microzonation: Site Class – Geology Relations


Microzonation: Site Class – Geology Relations

150010005000


6000400020000


Median profile with +/- 1 sigma

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25

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5

0

Depth (m

)

1.00.50.0

COV

1.00.50.0

COV

100

80

60

40

20

0

Dep

th (

ft)

6000400020000


150010005000


TL# 8 TL# 9 TL#10 TL# 11 TL# 13 TL# 15 TL# 17 TL# 32

GeologyNumber of

ProfilesMedian Vs,30m

(m/s)

NEHRP Site Class

Af 3 278 DQham 3 335 DQht2 1 346 DQphf 2 480 CQpf 8 499 CPpf 1 504 CPf 7 564 C

Mpb 3 513 CLmst 1 1014 B

Quaternary/Holocene

Quaternary/Pleistocene

Pliocene

Miocene

Shear wave velocity profile comparison for geologic unit QpfGeotechnical Lessons from the M7.0 Haiti Earthquake: Brady R. Cox, PhD, PE 18

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Site Classification Microzonation Map


Median Vs Profiles: Site Class D and C

Holocene/Site Class D Soils

fn ~ 5 Hz; Tn ~ 0.2 s; ~ 1-2 story buildings; Amp. Fact. ~ 2.5

fn < 2.5 Hz; Tn > 0.4 s; ~ 3-5 story buildings; Amp. Fact. ~ 2.5

Older/Site Class C SoilsGeotechnical Lessons from the M7.0 Haiti Earthquake: Brady R. Cox, PhD, PE 20

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Geologic Unit

Area (km2)

Heavily Damaged Buildings

Total Buildings

Damage Intensity

(%) Af 1.8 637 6368 10%

Qham 2.1 2790 7471 37% Qpf 4.5 2531 14,758 17% Pf 8.4 9202 35,666 26%

Mpb 6.8 7417 25,151 30% Lmst 3.6 729 5745 13%

Damage Relative to New Geologic Map

Downtown/Presidential Palace,“Reinforced” Concrete

Shanty,Little Damage

Topographic Effects?


Topographic Effects?


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Damage Relative to Slope Angle

Not all areas with the same building types, slope angles, and density experienced ‘topographic effects’

Study Area Geologic

Unit Topographic

Shape Landcover

Class Total

Buildings

Damage Intensity

(%) Fort

NationalPf Ridge

Bidonville / High Density

14,371 33%

St. Gerard North Mpb Ridge

High/Medium Density 2,797 55%

Hotel Montana

Mpb Ridge Medium Density

582 74%

St. Gerard South

Mpb Steep Valley Bidonville 3,467 32%

Bois PatateWest

Pf Steep Valley Bidonville 1,617 40%

Bois Patate East

Mpb Steep Valley Bidonville 730 48%


Hotel Montana

0

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30

0 500 1000 1500

Dep

th (m)

Vs (m/s)

TL 20 (0.5 km south of Hotel Montana)

TL21 (Hotel Montana)

Just topography? Strong impedance contrast. It can be difficult to decouple topographic and site effects.


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Conclusions

• In general, construction was poor everywhere, but this led to a tragically unique dataset of damaged structures for studying damage patterns

• Heavy damage in the downtown/Presidential Palace area was strongly influenced by soft‐soil amplification

• Topographic effects, no doubt, played a significant role in the damage patterns, but not all areas with the same construction and topography experienced similar damage

• It can be hard to separate site‐effects from topographic effects

• We now have a dataset of over 400,000 red/yellow/green tagged buildings to aid in our future investigations

• We have provided the Haitians with a preliminary microzonationmap of PaP that they can utilize during the rebuilding process


Acknowledgements

• NSF and GEER

• UNDP/Eric Calais

• Our colleagues in Haiti:

– Mr. Yves‐Fritz Joseph (Director General, Laboratoire National du Bâtiment et

des Travaux Publics d’Haïti)

– Mr. Dieuseul Anglade (Director General, Bureau des Mines et de l’Energie,

Haiti)

– Mr. Jean Robert Altidor (Bureau des Mines et de l’Energie, Haiti)


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Questions?


geotechnical lessons learned from the m7.0 2010 haiti...

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