Earthquake Mitigation in the Lisbon and Earthquake Mitigation in the Lisbon and

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13º Encontro Sociedade Brasileira de Geofísica 2013 13º Encontro Sociedade Brasileira de Geofísica 2013 13º Encontro Sociedade Brasileira de Geofísica 2013 13º Encontro Sociedade Brasileira de Geofísica 2013

Earthquake Mitigation in the Lisbon and Earthquake Mitigation in the Lisbon and

Lower Tagus Valley area, Portugal Lower Tagus Valley area, Portugal

Earthquake Mitigation in the Lisbon and Earthquake Mitigation in the Lisbon and

Lower Tagus Valley area, Portugal Lower Tagus Valley area, Portugal

Rio de Janeiro, 26

Rio de Janeiro, 26--29 August 29 August Rio de Janeiro, 26

Rio de Janeiro, 26--29 August 29 August

1 J. Carvalho, R. Dias, C. Pinto, T. Cunha, J. Leote 1 J. Carvalho, R. Dias, C. Pinto, T. Cunha, J. Leote

2 S. Vilanova, J. Narciso 2 S. Vilanova, J. Narciso

3 J. Borges 3 J. Borges 4 R. Ghose 4 R. Ghose

1 Laboratório Nacional Energia e Geologia, Portugal 1 Laboratório Nacional Energia e Geologia, Portugal

2 Instituto Superior Técnico, Portugal 2 Instituto Superior Técnico, Portugal 3 Centro Geofísica de Évora, Portugal 3 Centro Geofísica de Évora, Portugal

4 Delft University of Technology, The Netherlands 4 Delft University of Technology, The Netherlands

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Presentation Outline Presentation Outline

•• Introduction (seismicity, goals, problems) Introduction (seismicity, goals, problems)

•• Methodology (Data acquisition and Methodology (Data acquisition and processing)

processing) processing) processing)

•• VS30 and Soil Classification Maps VS30 and Soil Classification Maps

•• Conclusions Conclusions

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Study area tectonic setting Study area tectonic setting Study area tectonic setting Study area tectonic setting

after Jiménez

after Jiménez--Munt and Negredo, 2003 Munt and Negredo, 2003 -- EPSLEPSL

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Seismicity for the period 65 BC

Seismicity for the period 65 BC – – 2007 AD 2007 AD Seismicity for the period 65 BC

Seismicity for the period 65 BC – – 2007 AD 2007 AD

after Instituto Português Mar e Atmosfera after Instituto Português Mar e Atmosfera (IPMA)

(IPMA)

1755 1969

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Examples of Destructive Earthquakes Examples of Destructive Earthquakes Examples of Destructive Earthquakes Examples of Destructive Earthquakes

1969

1969 –– 12 deaths12 deaths 1909

1909 –– 46 “46 “

1755 ~ 30 000 “ 1755 ~ 30 000 “ 1531 ~ 1000 “ 1531 ~ 1000 “ 1344 100 < “ 1344 100 < “

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Goals Goals

•• Acquire shear wave data in the LTV regionAcquire shear wave data in the LTV region

•• Produce Soil Classification and VS30 mapsProduce Soil Classification and VS30 maps

•• Improve seismic hazard analysis and earthquake Improve seismic hazard analysis and earthquake mitigation

mitigation

Problems Problems Problems Problems

•• Limited amount of time and financing to acquire Limited amount of time and financing to acquire data

data

•• Complex geologyComplex geology

•• Unavailable digital lithostratigraphic maps Unavailable digital lithostratigraphic maps

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Metodology Metodology

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1) Acquisition and interpretation of:Acquisition and interpretation of:

Seismic refraction data (P & S) Seismic refraction data (P & S) MASW data

MASW data

Ambient vibration (single

Ambient vibration (single--station and array) station and array) 2)

2) Compare results at specific sites with well data Compare results at specific sites with well data 2)

2) Compare results at specific sites with well data Compare results at specific sites with well data available

available 3)

3) Use well data (geotechnical and water Use well data (geotechnical and water soundings) to interpret refraction data soundings) to interpret refraction data 4)

4) Produce VS30 and Soil Classification Produce VS30 and Soil Classification (Eurocode 8 based) maps

(Eurocode 8 based) maps

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Refraction Data Acquisition Refraction Data Acquisition

•• 2424 channelchannel forfor PP andand 2424 channelchannel forfor SS

•• PP--wavewave sourcesource:: hammerhammer andand plateplate

•• ShearShear wavewave sourcesource:: woodenwooden beambeam struckstruck onon bothboth sides

sides underunder thethe wheelswheels ofof aa JeepJeep Shear

Shear wavewave sourcesource:: woodenwooden beambeam struckstruck onon bothboth sides

sides underunder thethe wheelswheels ofof aa JeepJeep

•• ReceiverReceiver spacingspacing ofof 33..55mm:: totaltotal profileprofile lengthlength 8484 mm

•• 22 endend--shotsshots andand 33 insideinside layoutlayout shotsshots (first(first layerlayer &&

reciprocal

reciprocal times)times)

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P

P--wavewave sourcesource

Shear

Shear--wavewave source source

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Example shot gathers Example shot gathers

P

P--wavewave

Shear

Shear--wavewave

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Refraction Data Interpretation Refraction Data Interpretation

•• CommercialCommercial softwaresoftware usingusing generalizedgeneralized reciprocalreciprocal method

method (Palmer,(Palmer, 19811981)) andand slopeslope interceptintercept

•• UseUse detaileddetailed geologicalgeological andand lithologicallithological datadata collected

collected atat eacheach sitesite collected

collected atat eacheach sitesite

•• UseUse nearbynearby wellwell datadata atat samesame elevationelevation

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Examples of Refraction TD curves & models

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P and S

P and S--wave wave Data collected at Data collected at

42 sites

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Comparison of Refraction & Ambient Comparison of Refraction & Ambient

Noise Data Noise Data

Teves

Teves--Costa et al., 2013 Costa et al., 2013

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Preliminary 1: 10

⁶⁶

scale VS30 Map scale VS30 Map using refraction and ambient noise using refraction and ambient noise

Teves

Teves--Costa et al., 2013 Costa et al., 2013

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Preliminary 1: 10

⁶⁶

scale VS30 Map scale VS30 Map using refraction data

using refraction data

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Preliminary 1: 10

⁶⁶

scale VS30 Map scale VS30 Map using refraction data

using refraction data

Santarém Santarém

Lisbon Lisbon

Setúbal Setúbal V. F. Xira

V. F. Xira

Benavente Benavente

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Preliminary Soil Classification Map

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Soil Classification

Soil Classification -- Criteria used Criteria used

CLASS CRITERIA 1 CRITERIA 2

Subsoil class A ^Rockcharacterized by Vs >= 800 m/s^or ^geologic ^formation

Compact deposits of sands, gravels or overconsolidated clays, several tens of meters thick (Vs >= 400 m/s at 10m depth)

B

Deep deposits of medium dense sands, gravel or stiff clays with thickness from several tens to Subsoil class B ^thicknesshundreds of meters (Vs >= 200 m/s^from ^several ^tens ^to at depth to Vs >= 350 m/s at 50m depth (SPT N~60)

Subsoil class C

Loose cohesionless deposits with or without soft cohesive layers (Vs <

200 m/s at depths <20m (SPT N<=10)

Deposits with soft-to-medium stiff cohesive soils (Vs < 200 m/s at depths <20m (SPT N<=10)

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Preliminary Soil Classification Map

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Preliminary Soil Classification Map Preliminary Soil Classification Map

•• Class C correspond to Holocene and Pleistocene sediments Class C correspond to Holocene and Pleistocene sediments

•• Holocene alluvium also have areas classified as B Holocene alluvium also have areas classified as B

•• Pleistocene sediments show large variation and are also classified Pleistocene sediments show large variation and are also classified

•• Pleistocene sediments show large variation and are also classified Pleistocene sediments show large variation and are also classified B or A

B or A

•• Miocene formations can be either classified B or A Miocene formations can be either classified B or A

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Conclusions Conclusions

•• AtAt thisthis firstfirst phasephase ofof thethe studystudy thethe highlyhighly complex

complex geologicalgeological naturenature ofof thethe studystudy areaarea where

where thicknessthickness andand laterallateral lithologicallithological changes

changes areare constant,constant, preventsprevents aa simplesimple changes

changes areare constant,constant, preventsprevents aa simplesimple geographical

geographical generalizationgeneralization ofof thethe velocityvelocity andand soil

soil classificationclassification datadata pointspoints..

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Conclusions Conclusions

•• PreliminaryPreliminary VSVS3030 andand thethe soilsoil classificationclassification maps

maps presentedpresented herehere highlighthighlight aa regionregion ofof greatgreat susceptibility

susceptibility toto earthquakeearthquake shakingshaking andand wherewhere several

several citiescities areare locatedlocated.. ThisThis regionregion isis several

several citiescities areare locatedlocated.. ThisThis regionregion isis covered

covered byby HoloceneHolocene alluviumalluvium butbut otherother areasareas located

located overover olderolder geologicalgeological formationsformations alsoalso show

show aa relativelyrelatively moderatemoderate riskrisk..

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•• Portuguese Foundation for Science and Portuguese Foundation for Science and Technology for funding Projects:

Technology for funding Projects:

NEFITAG; SCENE; SHELT NEFITAG; SCENE; SHELT

••Field crew: F. Caneiras, J. GomesField crew: F. Caneiras, J. Gomes

•• Portuguese Foundation for Science and Portuguese Foundation for Science and Technology for funding Projects:

Technology for funding Projects:

NEFITAG; SCENE; SHELT NEFITAG; SCENE; SHELT

Acknowledgements Acknowledgements Acknowledgements Acknowledgements

••Landowners: Eng Rui Paixão, Companhia das Landowners: Eng Rui Paixão, Companhia das Lezírias

Lezírias

••Landowners: Eng Rui Paixão, Companhia das Landowners: Eng Rui Paixão, Companhia das Lezírias

Lezírias

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References References

Jimenez

Jimenez--MuntMunt,, II.. andand NegredoNegredo,, AA..MM..,, 20032003,, NeotectonicNeotectonic modellingmodelling ofof the

the westernwestern partpart ofof thethe AfricaAfrica--EurasiaEurasia plateplate boundaryboundary:: fromfrom thethe MidMid-- Atlantic

Atlantic ridgeridge toto Algeria,Algeria, EarthEarth andand PlanetaryPlanetary ScienceScience Letters,Letters, 205205,, 257257-- 271

271..

Palmer,

Palmer, DereckeDerecke,, 19811981,, AnAn introductionintroduction toto thethe generalizedgeneralized reciprocalreciprocal Palmer,

Palmer, DereckeDerecke,, 19811981,, AnAn introductionintroduction toto thethe generalizedgeneralized reciprocalreciprocal method

method ofof seismicseismic refractionrefraction interpretation’,interpretation’, Geophysics,Geophysics, 4646,, 15081508-- 1518

1518..

Teves

Teves--Costa,Costa, PP..,, RodriguesRodrigues,, II..,, Torres,Torres, RR..JJ..GG..,, CarvalhoCarvalho,, JJ..,, Almeida,Almeida, II..MM..,, Borges,

Borges, JJ..FF..,, 20132013,, VsVs3030 estimationestimation usingusing ambientambient vibrationsvibrations andand seismic

seismic refractionrefraction experimentsexperiments -- ApplicationApplication toto thethe LowerLower TagusTagus ValleyValley (Portugal),

(Portugal), AbstractsAbstracts ofof thethe JointJoint AssemblyAssembly IAHSIAHS--IAPSOIAPSO--IAPSEI,IAPSEI, 2222--2626 July,

July, GotemburgGotemburg (Sweden)(Sweden)..

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Thank You !

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