Probabilistic Seismic Hazard Maps - Inputs and Status

Choi Yoon Seok

Jennifer S. Haase

Robert L. Nowack

Purdue University

Status

• Preliminary data sets used as of 11/20/05• Approximate bedrock topography and surface

wave velocity model constructed.• Preliminary v1.0 full calculation completed and

presented at Fall AGU 12/8/05– Very sensitive to bedrock depth

• Second calculation using new version of Cramer’s PSHA code completed 2/18/06– 0.2 sec expected acc. Increased by ~0.1g– Investigated larger period range

• Third run with finalized model planned 4/06

Legend

PGA_0.05

Prediction Map

[Amp_pga_all].[A_2]

Filled Contours

1 - 1.4

1.4 - 1.8

1.8 - 2.2

2.2 - 2.6

2.6 - 3

3 - 3.4

3.4 - 3.8

3.8 - 4.2

4.2 - 4.6

4.6 - 5

5 - 5.4

5.4 - 5.8

5.8 - 6.2

6.2 - 6.6

6.6 - 7

Site amplification factor

Amplification Factor

Legend

PGA_0.05

Prediction Map

[Amp_pga_all].[A_2]

Filled Contours

1 - 1.4

1.4 - 1.8

1.8 - 2.2

2.2 - 2.6

2.6 - 3

3 - 3.4

3.4 - 3.8

3.8 - 4.2

4.2 - 4.6

4.6 - 5

5 - 5.4

5.4 - 5.8

5.8 - 6.2

6.2 - 6.6

6.6 - 7

Site amplification factor

Amplification Factor

PSHA mapsUSGS_A02

Prediction Map

[Level4.0_2%PE_50Yr_PSHA_USGS].[A02]

Filled Contours

-0.3 - -0.2

-0.2 - -0.1

-0.1 - 0

0 - 0.1

0.1 - 0.2

0.2 - 0.3

0.3 - 0.4

0.4 - 0.5

0.5 - 0.6

0.6 - 0.7

0.7 - 0.8

0.8 - 0.9

0.9 - 1

1 - 1.1

1.1 - 1.2

1.2 - 1.3

1.3 - 1.4

1.4 - 1.5

1.5 - 1.6

1.6 - 1.7

Acceleration Level (g)

Data inputs

• 48 USGS CPT– Used to assign Vs to unit types - loess, alluvium,

lacustrine - averaged over depth to one Vs

• 33 borehole Vs– Used to assign Vs to unit types - averaged over depth

to one Vs

• 570 new SPT at 60 geotechnical sites– Not used - not satisfied with SPT => Vs

• 230 Vp refraction– Used for depth to bedrock– Used for bedrock velocity (Vs=Vp/1.72)

Data inputs

• KGS Vs refraction profiles (CUSEC report)– Used only to check approx bedrock Vs

• IGS Ilith water well logs– Used for bedrock depth– Not used for densifying lateral varying

lithology, yet…

• KY bedrock elevation points (R. Counts)

Data inputs

• Surficial geology– Used to determine surface lithology type,

then one velocity and uncertainty assigned to all grid points within that map area

– All these surficial geology maps were preliminary products

Quadrangle Map Status?Caborn (name?) Quadrangle surficial maping – IN side IGS surficial mapping – KY side KGS Steve Martin 11/2005 KGS Ron Counts revising bedrock contours 4/2006?

Evansville N Quadrangle prelim surf mapping Scott Lundstrom 11/2005 final surf mapping ?

Daylight Quadrangle surf mapping IGS – old GIS database Scott Lundstrom ?

West Franklin surf mapping KGS Steve Martin 11/2005 KGS R. Counts revising bedrock contours 4/2006 Dave Moore

Evansville S prelim surf mapping Scott Lundstrom 11/2005 final surf mapping

Newburgh field mapping done 4/2006? Scott Lundstrom existing surf mapping KGS DVGQ map

Wilson

Henderson Spottsville field mapping done 4/2006? Mike Murphy Mark Thompson existing surf mapping KGS DVGQ map

Bedrock depth model

Effect of depth of soil on amplification

• At 0.05 g input

Legend

PGA_0.05

Prediction Map

[Amp_pga_all].[A_2]

Filled Contours

1 - 1.4

1.4 - 1.8

1.8 - 2.2

2.2 - 2.6

2.6 - 3

3 - 3.4

3.4 - 3.8

3.8 - 4.2

4.2 - 4.6

4.6 - 5

5 - 5.4

5.4 - 5.8

5.8 - 6.2

6.2 - 6.6

6.6 - 7

Site amplification factor

What’s left to try?

• Use more data to determine correspondence between velocity and unit lithology

• Water wells and SPTs : calculate average velocity given the total thickness of different units using lithology for each unit

• Try a depth dependence for each unit• Need some kind of numbers for bedrock• Refraction data in Ron’s marginal areas• Make cross sections through our Vs/bedrock model

for detailed cross section lines to make sure they are consistent with detailed depositional cross sections.

Products

• PSHA maps at any level desired– Level of acceleration in g with X% probability to be

exceeded in 50 years– At pga, 0.2 sec, 1 sec (or others)– 9 quadrangle region

• Scenario earthquake calculation for Indiana side? Using same scenarios as Zhenming?

Products

• From 3D Vs above bedrock model can calculate site classification

• Give information to CUSEC to make updated NEHRP soil classification maps

• These could be available products to other scientists and also users of HAZUS