HAZARD #1: EARTHQUAKES

7.1 Araucania earthquake (Chile, 2011)

Earthquake: result of a sudden release of energy in the Earth’s crust that creates seismic waves, followed by smaller aftershocks and potential secondary hazards (ex: tsunamis, industrial leaks, etc)

SAN ANDREAS FAULT

1. Describe the crustal movement of the San Andreas fault

2. Explain how this tectonic plate boundary different from the one near Seattle in its movement and geographical manifestation

EARTHQUAKE CHARACTERISTICS: PLATE BOUNDARY TYPES – Find regional examples for each type

Oceanic-Continental convergence

Shallow focus = ~100 km depth or lessDeep focus = 100-700 km depth

P-waves (primary / push-pull) = felt first (5-8 km/s): feels like a shock wave rattling windowsS-waves (secondary / shake) = felt a few seconds later (3-5 km/s): can be very destructive

Ex 1: Loma Prieta (California 1989): 6.7 magnitude at 18 km depth (inland)Ex 2: Sendai (Japan 2011): 9.0 magnitude at 32 km depth (70 km the coast)

EARTHQUAKE CHARACTERISTICS: FOCUS, EPICENTER, DEPTH, SHOCKWAVES

SOIL LIQUEFACTION DUE TO EARTHQUAKES

Explain factors linked to the high soil liquefaction risk

SECONDARY HAZARDS DUE TO EARTHQUAKES

Mudslide in Taiwan (2010)

Fire in San Francisco (1906)

Tsunami in Japan (2011)

EARTHQUAKE CHARACTERISTICS: DAMAGE FACTORS

Explain how each of the following factor can affect the outcome of an earthquake:

• Strength and depth of earthquake• Number of aftershocks• Population density• Type of buildings• Time of day• Distance from epicenter• Types of rocks -> risk of liquefaction• Secondary hazards: tsunami, fire, mudslides, famine, epidemic• Development level (linked to preparedness and response)

3 most destructive recent earthquakes1. Indonesia 2004 (9.1) 250,000 victims (tsunami)2. Haiti 2010 (7.0) 230,000 victims3. Pakistan 2005 (7.6) 86,000 victims

Most destructive recent earthquakes

EARTHQUAKE SPATIAL DISTRIBUTION: TECTONIC PLATE BOUNDARIES

CASE STUDIES IN TEXTBOOK:Comparable strength earthquakes with different outcomes (p.201):• Kobe (Japan, 1995, 7.2): 5,000 victims• Kashmir (Pakistan, 2005, 7.6): 86,000 victims

1. Suggest reasons why the Kobe earthquake was so devastating2. Explain why the Kashmir earthquake was more devastating than the one in Kobe

EARTHQUAKE SPATIAL DISTRIBUTION: THE “RING OF FIRE” ON THE PACIFIC RIM

Convergence (subduction) zones:

1. Name large four large cities located on the “ring of fire”2. Explain why some regions located on the “ring of fire” are more vulnerable to

earthquake hazards than others

EARTHQUAKE SPATIAL DISTRIBUTION: SEISMIC HAZARD

1. Name a megacity exposed to a high seismic hazard resulting from:• Lateral sliding• Subduction

2. For one named vulnerable region, explain what factors may increase the seismic hazard