1 of 14

Seismic Microzonation and Basin Effects:

How do we apply the latest and greatest in hazard mapping in practice, from land use and emergency management planning to building design and retrofit? 

2 of 14

Seismic Microzonation Maps:

Are interpretations of seismological, geological, geotechnical, and geophysical data

Depict variations of seismic hazard in a region

Can be used to predict where earthquake effects will be greater or lesser than code

Will show amplified ground shaking, and the likelihood of liquefaction and landslides

Are not risk maps, but may be an input to risk assessments

3 of 14

1940s – Victoria - amplification

1980s – Fraser River Delta – amplification & liquefaction

1990s – Greater Vancouver – amplification & liquefaction

2000s – Greater Vancouver & Victoria – amplification

2010-2020s – Greater Vancouver – amplification, liquefaction, & landslide

Other Canadian Amplification Maps

Montreal

Ottawa

Quebec City

St. Lawrence Lowlands

NBC 1965

NBC 1975

NBC 1990

NBC 2005

NBC 2015 & NBC2020

4 of 14

Geology

Topographic

Surficial

Quaternary

Depth to Bedrock

Subsurface Data Point

Ground Shaking

Vs30, Vs,ave

Site Period (T0)

Depth to Vs = 1.5 km/s

Amplification Hazard Maps (various site and return periods)

Basin Amplification Hazard Maps (various site periods and EQ sources)

Liquefaction

Groundwater Table

Liquefaction Susceptibility

Thickness of Liquefiable Deposits

Vertical or Lateral Displacement

Seismic-Induced Liquefaction Hazard (475- and 2475-year return periods)

Landslide

Topographic Slope

Landslide Susceptibility

Landslide Displacement

Landslide Inventory

Seismic-Induced Landslide Hazard Maps (1/475 and 1/2475 annual exceedance probabilities)

5 of 14

Users

Local Authorities

Emergency Management Planners

Building & Infrastructure Owners

Real Estate & Insurance Industries

Catastrophic Hazard & Risk Modelers

Geotechnical Engineers

Structural Engineers

6 of 14

7 of 14

Tamsin Mills

Carlos Molina Hutt

John Sherstobitoff

Sheri Molnar

Allison Chen

8 of 14

Question 1:

Why are people talking more and more about seismic microzonation maps? What are your expectations related to the Metro Vancouver Seismic Microzonation Mapping Project and the complementary EGBC professional practice guidelines?

9 of 14

Question 2:

How have seismic microzonation maps been used in BC and Canada to date? How do you hope these new seismic microzonation maps will be used, or where do you see the greatest potential for their use (e.g., untapped market)?

10 of 14

Question 3:

What is special about the geology and seismology of BC (particularly the lower mainland)? Is this an issue elsewhere in the world? What can we learn from research, practice, codes, and policies in other jurisdictions?

11 of 14

Question 4:

How do seismic microzonation maps relate to the building code? What information can you get from one compared with the other, and are they complementary or contradictory?

12 of 14

Question 5:

How do seismic microzonation maps fit in with existing hazard assessments used in municipal risk assessments, land use planning, and emergency management planning? What do you see as the biggest challenge for local authorities?

13 of 14

Question 6:

How can structural and geotechnical engineers incorporate the use of microzonation maps into their typical workflow? How could/should they be used for the design of new buildings and/or retrofit of existing ones?

14 of 14

Final Thoughts:

Wrapping this up with a high-level question and opportunity to share any last-minute thoughts. What do you see as the biggest change to “business as usual”?