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 .