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Suppose that local fire and rescue crews had to prioritize which of the "Strong Shaking Case Studies" areas to search first for earthquake survivors and casualties.

Which area (N1, N2, E1, or E2) should get priority? Why?

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Structural Damage, 1989 Loma Prieta Earthquake, J.K. Nakata, USGS

Why did the first floor of this apartment building collapse, whereas the upper stories were mostly unaffected?M 6.9 Loma Prieta (CA) October 17, 1989Depth: 18.0 km Ground type: Artificial fill

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This activity addresses the following learning objectives:1. Students will relate earthquake damage to

rock/soil type and distance from epicenter.2. Students will identify factors that contribute

to building damage associated with earthquakes, and will describe potential strategies to mitigate seismic damage to buildings.

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Mw 6.8 Nisqually (WA), Feb 28, 2001

Depth: 52 kmGround type: Dominantly glacial and river sediments and volcanic rocks.

Mw 6.7 Northridge (CA) Jan 17, 1994

Depth: 18 kmGround type: Alluvial and marine sediments; crystalline (igneous and metamorphic) rocks.

What effect does an earthquake’s depth have on the damage it does?

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Buildings on loose fill may sink as sediment liquefies during an earthquake.Collapsed building in the Marina District, San Francisco, 1989 Loma Prieta Earthquake, D. Perkins, USGS

M 6.9 Loma Prieta (CA) October 17, 1989Depth: 18.0 kmGround type: Artificial fill (right), alluvial sediment? (left)

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Earthquakes can trigger landslidesGovernment Hill landslide, Anchorage, Alaska, 1964 Prince William Sound Earthquake, USGS

M 9.2 Prince William Sound (AK) March 27, 1964Depth: 6.3 kmGround type: Clay-rich?

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Building materials greatly affect seismic safety. Unreinforced masonry or wood are particularly prone to damage.

Unreinforced masonry building in Fillmore, 1994 Northridge Earthquake, J. Dewey, USGS

Mw 6.7 Northridge (CA) January 17, 1994Depth: 18 kmGround type: Alluvial and marine sediments; crystalline (igneous and metamorphic) rocks.

Damage to an old Buddhist temple. Note that the (more modern) building next door is unharmed. Photo: R. Hutchison, NOAA.

Mw 6.9 Kobe (Japan) January 16, 1995Depth: 22 kmGround type: Unknown

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The first floor of this building contained large open spaces (“soft stories”), in this case stores. Photo: R. Hutchison, NOAAMw 6.9 Kobe (Japan) January 16, 1995Depth: 22 kmGround type: Unknown

How do undivided floor plans affect a building’s seismic safety?

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Mitigating Construction Problems

• Reinforcement: Bracing, shear walls (best for soft stories)

• Base isolation: Flexible link between building and foundation

• Vibration damping: Add devices to resist shaking

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Mitigating Settlement / Liquefaction

• Reinforce structure to mitigate small motion• Improve foundation: deep piles, flexible piles,

mat foundation• Stabilize soil: dewater, grout, densify, buttress

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These two buildings were both constructed of unreinforced masonry. The building on the right experienced more damage: why?

Mw 6.8 Nisqually (WA), February 28, 2001Depth: 52 kmGround type: Dominantly glacial and river sediments,volcanic rocks.

Mw 6.7 Northridge (CA) January 17, 1994Depth: 18 kmGround type: Alluvial and marine sediments; crystalline (igneous and metamorphic) rocks.

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Leaning apartment houses in Niigata, Japan, 1964 Niigata Earthquake, NOAA National Geophysical Data Ctr

Mw 7.5 Niigata, Japan June 16, 1964Depth: 40 kmGround type: Sand, younger deposits on left, older and more consolidated toward right

Why do some of these buildings lean, while others are upright?

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Why did one of these buildings experience major damage, particularly to its façade, when its neighboring building was relatively unaffected by the same earthquake? Examine the rubble pile and building facades for clues.

M 6.9 Loma Prieta (CA) October 17, 1989Depth: 18.0 kmGround type: Artificial fill

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Structural Damage, 1989 Loma Prieta Earthquake, J.K. Nakata, USGS

The first floor of this wooden San Francisco apartment was mainly garages. It is now “pancaked,” whereas the second and third floors are unaffected. Why?

M 6.9 Loma Prieta (CA) October 17, 1989Depth: 18.0 km Ground type: Artificial fill

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Collapsed apartment in Reseda, 1994 Northridge Earthquake, J. Dewey, USGS

The first floor of apartment building near Northridge was mainly garages. It is now “pancaked,” whereas the second and third floors tilted like rigid blocks. Why?

Mw 6.7 Northridge (CA) January 17, 1994Depth: 18 kmGround type: Alluvial and marine sediments; crystalline (igneous and metamorphic) rocks.

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Mw 7.4 Kocaeli/Izmit, Turkey August 17, 1999Depth: 15.9 kmGround type: Unknown

What made this building so risky?

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Hazard Vulnerability Value Analysis

Name of School

A:Peak

Ground Accelerati

on

B: Liquefa

ction Potenti

al

C: Landslide

Potential

D: Soft Stories?

E: Unreinforced Masonry

F: Vertical or

Plan Irregularit

y

G: Number of

Students

Risk Facto

rRecommendation (from class discussion)

Marina1 Marina2 Francisco1 Francisco2 Garfield1 Garfield2 HHoover1 HHoover2 Guadalupe1 Guadalupe2 Sunset1 Sunset2

Assess risk at public school campuses around San Francisco

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Discussion Questions

1. Which two schools should receive $10 million for seismic retrofitting?

2. What measures would you recommend to mitigate seismic risk at each school campus? At some schools, other measures may be more effective at mitigating risk than seismic retrofitting.

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Discussion Questions

3. As a result of learning about calculated risk, you may have changed the way you think about prioritizing emergency services in the event of an earthquake. Would you change your answer from the prework? If so, what about it would you change, and why? If not, what convinced you that it was correct?

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Writing Assignment

Based on your risk assessment of the five schools in this activity, make the case for funding upgrades to buildings at two schools.

Prepare a set of bullet points to be presented to the City of San Francisco that uses data from your analysis to support your recommendations. If additional measures are necessary to mitigate risk at other schools, outline them and support them as well.