1. Tri-State Seismic Hazard Mapping -Kentucky Plan
Zhenming Wang
Kentucky Geological Survey
University of Kentucky
February 23, 2006

2. Outline Seismic Hazards KGS Seismic Hazard Mapping – Kentucky Plan
Primary Hazard – Ground Motion (on bedrock)
Scenario ground motion
USGS Hazard Maps (PSHA)
Secondary Hazard
Ground Motion Amplification (NEHRP Soil type)
Liquefaction
Induced slope instability
KGS Seismic Hazard Mapping – Kentucky Plan
Primary Hazard

3. Seismic Hazard and Risk
Seismic hazard and risk are fundamentally different
Seismic Hazard
Natural phenomena generated by the earthquake, such as surface rupture, ground motion, ground-motion amplification, liquefaction, and induced-landslide that have potential to cause harm
Measurement: level of hazard and its recurrence interval
Seismic Risk (More Subjective)
likelihood (chance) of experiencing a level of seismic hazard for a given time exposure

4. Seismic and Hurricane Hazards and Risk
New Madrid earthquake
Event
Hurricane (Katrina)
~M7.7
Size
Category V
~500
τ (years)
~100?
~10% in 50 years
Risk
~39% in 50 years
PGA/MMI/PSA
Hazard at a specific site
Flood level/Wind speed $X
Loss $Y
Log-normal
Uncertainty of measurement
Normal/Log Pearson
Only Seismic Hazards Are
Considered by KGS

5. Ground Motion Secondary: Amplification (NEHRP soil) Liquefaction
Slope failure
Primary: USGS maps
Policy considerations:
IBC, IRC, and etc.

7. USGS Memphis Project
(Cramer and others, 2006)
De-amplification
Amplification

9. Seismic Hazard Maps – KY Plan
Ground Motion Hazard Maps
Level of ground motion
How often it could occur
A set of scenario maps (ground motion vs. recurrence time)
Secondary Hazard Maps
Amplification map
Liquefaction potential map

10. Ground Motion Maps Earthquake Sources Ground Motion Attenuation
Faults
Occurrence frequency
Maximum magnitude
Ground Motion Attenuation
Methodology
PSHA
DSHA

11. Earthquake Sources 1. Where? 2. How Big? 3. How Often? Thousands years
Historical Event: White County EQ?
(~M7.5?, Mueller et al., 2004)
Paleo-liquefactions (Obermeier et al.)
1993/1996
2005
Waverly
6.8
6.2
Vallonia
6.9
6.3
Skelton
7.2
6.7
Vincennes
7.8
7.3/7.1

12. Ground Motion Attenuation
Conservative predictions (USGS WP, 2005)
New attenuations (USGS WP, 2006)

13. Methodology PSHA vs. DSHA
Same thing under certain conditions (Characteristic earthquake)
But different expressions
PGA maps with 5% PE in 50 years
(Cramer et al., 2006) =
The maps may good for NMSZ (AASHTO
,KGS, and others)
But good for the Tri-State Area?

14. Ground Motion Amplification
Directly
Vertical Strong Motion Stations
H/V spectral ratios (e.g. earthquakes and ambient noise)
Theoretical Modeling
Response based on amplification thru the Vs gradient of the soils/ sediments (e.g., SHAKE, etc.)
Empirical
NEHRP Soil Classification

15. Notes: 1) based on CA geology: bedrock Vs~2,500 ft/s (B/C boundary)
Example 1
Example 2
Average Equation
Vs=500 (ft/s)
d=30 (ft)
Vs=500 (ft/s)
d=70 (ft)
Vs=1000 (ft/s)
d=40 (ft)
Vs=1500 (ft/s)
d=50 (ft)
Vs=4000 (ft/s)
(bedrock)
Vs=4000 (ft/s)
(bedrock)
Vs=4000 (ft/s)
(bedrock)
100/(70/500+30/4000)=678 (ft/s)
=> D ( ft/s)
100/(30/500+40/ /1500)=833 (ft/s)
=> D ( ft/s)
Notes: 1) based on CA geology: bedrock Vs~2,500 ft/s (B/C boundary)
2) in CUS, bedrock Vs >2,500 ft/s (A or B), applicable (?)

17. C C D
(Street et al., 1997, Engineering Geology, 46: )

18. Further analysis based on: SPT, CPT, Vs values and INPUT MOTION
Table 3. Estimated Susceptibility of Continental Deposits to Liquefaction (modified from Youd and Perkins, 1978).
Type of deposit
Likelihood that Cohesionless Sediments, When Saturated, Would Be Susceptible to Liquefaction (by Age of Deposit)
<500 yr
Holocene
Pleistocene
Pre-Pleistocene
River channel
Very high
High
Low
Very low
Flood Plain
Moderate
Alluvial fan and Plain
Lacustrine and playa
Colluvium
Talus
Tuff
Residual soils
Step 1.
Step 2.
Further analysis based on: SPT, CPT, Vs values and INPUT MOTION

19. Louisville Liquefaction Potential Map

20. Summary KGS will produce following maps for KY
Ground Motion Hazard Maps
A set of scenario maps (ground motion level vs. recurrence time)
Secondary Hazard Maps
Amplification maps (associated with the scenario maps)
Liquefaction potential maps (associated with the scenario maps)
All data will be available after completion of the maps

21. Thank You