The “solid” Earth…
…moves, shakes,
rattles and rolls,
and occasionally
blows its top
Chapter 9
Earthquakes and Volcanoes
At 7:40 PM,
a magnitude 2.6 earthquake
struck a sparsely inhabited
area …
Earthquakes: Sep. 30 – Oct. 10, 2003
…near Jasper, AB
Historical seismic activity in Canada
Two types of crust “float”
on the upper mantle:
• oceanic crust (heavier, sinks lower)
• continental crust (lighter, floats higher)
Three types
of plate convergence
• oceanic – continental
• oceanic – oceanic
• continental - continental
Oceanic – continental plate convergence
Nazca plate – South America plate
Oceanic – oceanic plate convergence
New Hebrides Trench near Vanuatu
Continental – continental plate convergence
India/Eurasia plate collision
(forms Himalayan Mountains)
Earthquake motions…
1906 San Francisco Earthquake
Mercalli
Richter
1964 Alaska earthquake damage
map: modified Mercalli scale
III - IV
V
VI
VII
VIII - X
Mercalli
Richter
Liquefaction and slumping
Anchorage, Alaska - 1964
Earthquake-proof buildings
Question
- Is a major earthquake in California, Alaska
or Japan of any concern thousands of
kilometers away in Hawaii?
Tsunami
(seismic wave)
Tsunami power
Volcanoes
Volcanic landforms
Effusive eruptions (gentle flows, lots of lava)
• cinder cones
• shield volcanoes
• plateau basalts
Explosive eruptions (viscous lava, trapped gases)
• composite volcanoes
• calderas
Cinder cone
Big Cinder Butte, Craters of the Moon, Idaho
- forms small hills
- black scoria rock with air bubbles
Shield volcano
Mauna Loa, Hawaii
•
Kilauea, Hawaii
Seamounts
Hot spot
Plateau basalts
Composite volcano
Shield / composite volcano comparison
Mount St. Helens: the day before
- flooding (from steam-melted ice and snow)
Four years later
Caldera
Crater Lake, Oregon
6600 years ago
windblown ash landed
in Calgary
Volcanic hazards and effects
•
•
•
•
•
•
•
hot ash (pyroclastics)
steam and gas explosions
lava flows
poisonous gases (carbon dioxide, sulfuric acid)
landslides
tree blowdowns
lahars (steam-melted ice and snow cause
flooding and large mudflows)
• increase in atmospheric dust (decreased global
temperatures)
Volcanic benefits
• new fertile soils
- Hawaii, Philippines
• geothermal energy
- Iceland, Italy, New Zealand
• new real estate
- Iceland, Japan, Hawaii
Diamond-bearing kimberlite pipe