Why do we have earthquakes? …
Pacific Plate British Columbia
Vancouver
Juan de Seattle Fuca Plate Washington Locked subduction earthquake Portland source zone
Oregon
200 km California NRCan Natural Resources Canada How likely are we to have a damaging earthquake?…
M 8-9
M 7
M 6 Subduction earthquakes
Pacific Plate British Columbia
Vancouver
Juan de Seattle Fuca Plate Washington Locked subduction earthquake Portland source zone
Oregon
200 km California
Natural Resources Canada Clague et al., 2006 Crustal earthquakes
7 8
9
6
5 4
3 1
2
potential active fault
Clague et al., 2006 1 Straight Creek fault 2 Seattle fault 3 southern Whidbey Island fault 4 Devil Mountain fault 5 Leech River fault 6 Cowichan Lake fault 7 Beaufort Range fault 8 Strait of Georgia fault 9 Vedder and Sumas Mountain fault Prince 1946 Prince 2001 Rupert Vancouver Island Rupert Nisqually, Washington earthquake Shake maps earthquake magnitude 7.3 (Mercali intensity) magnitude 6.9 Campbell River: 75% of chimneys General alarm. collapse VII Difficult to stand. Damage to buildings. >$2 billion Lions Gate dollars in Bridge sways Courtenay: Felt by everyone. damage Post Office VI Difficult to walk. wall collapses Objects fall. Vancouver Vancouver Felt outdoors, Port Alberni: Victoria V Victoria Hundreds of Buildings sway. houses lose Seattle Seattle chimneys. Water Felt by most mains break. buildings IV people indoors. Power out for sway 10 days. Portland Portland
Clague and Turner, 2003 0 km 300 0 km 300
fig27.cdr
Pacific Plate British Columbia
Nootka fault
Vancouver
Juan de Seattle Fuca Plate Washington Locked subduction earthquake Portland source zone
Oregon
200 km California As in real estate, it’s location, location, location! …
Magnitude 7
Significant damage
Disaster Magnitude 6
Minor losses
Major damage Magnitude 4
Ho-hum!
Conversation piece Effects of strong earthquakes
• Ground shaking • Tsunami • Liquefaction • Landslides • Fire • Aftershocks Effects of strong earthquakes
• Ground shaking • Tsunami • Liquefaction • Landslides • Fire • Aftershocks
Ground motion depends on many things… … including geology and topography
NRCan Ground motion amplification
Clague and Turner, 2003 Effects of strong earthquakes
• Ground shaking • Tsunami • Liquefaction • Landslides • Fire • Aftershocks
Tsunami
tsunami wave cm 300 crest
200
100
0
-100
-200
-300 trough
fig102.cdr Effects of strong earthquakes
• Ground shaking • Tsunami • Liquefaction • Landslides • Fire • Aftershocks Liquefaction
Christchurch 2011
sand volcano
crack landslide clay stream
liquefied sand
clay Effects of strong earthquakes
• Ground shaking • Liquefaction • Landslides • Fire • Aftershocks CBC
Duncan Wyllie Effects of strong earthquakes
• Ground shaking • Liquefaction • Landslides • Fire • Aftershocks Kobe 1995
San Francisco 1906 Effects of strong earthquakes
• Ground shaking • Ground rupture • Liquefaction • Landslides • Fire • Aftershocks