1. How do tectonic processes affect the magnitude of earthquakes?
1. Tectonic processes of earthquakes
a) stress builds up and exceeds strength of the fault
b) sudden release of seismic waves, radiating energy from the focus
2. Magnitude of earthquakes
a) affected by amount of energy released through ground movement
b) recorded using seismometers
3. Measuring earthquakes
a) Richter Scale measures local magnitude of earthquakes
b) Moment Magnitude Scale measures larger earthquakes more reliably
2. How do tectonic processes affect the magnitude of volcanic eruptions?
1. Tectonic processes of volcanic eruptions
a) magma consisting of dissolved gases is less dense
b) forces its way upward and breaks through weak areas in the Earth’s crust
2. Magnitude of volcanic eruptions
a) determined by amount of dissolved gases and magma viscosity
b) stratovolcanoes erupt violently and shield volcanoes emit magma gently
3. Measuring volcanic eruptions
a) Volcanic Explosivity Index measures relative explosivity of historic eruptions
b) considers the volume of ejected materials, height of eruption cloud and duration of the eruption
3. How might distribution of earthquakes and volcanoes influence the spread of tectonic hazards?
1. Distribution of earthquakes
a) along all plate boundaries
b) largest concentration at the Pacific Ring of Fire
2. Distribution of volcanoes
a) located near convergent and divergent plate boundaries
b) hot spot volcanoes are found away from plate boundaries
3. Distribution of tectonic hazards
a) most located near plate boundaries, and near earthquakes and volcanoes
b) tsunamis and volcanic ash may spread beyond geographic region
4. How might tectonic hazards affect the natural and human systems?
1. Earthquake hazards and their impacts
a) hazards include ground shaking, soil liquefaction, landslides and tsunamis
b) impacts include destroying ecosystems, properties and infrastructure; disrupting services; and causing injury and loss of life
2. Volcanic eruption hazards and their impacts
a) hazards include tephra, volcanic gases, lava flows, pyroclastic flows, lahars and volcanic landslides
b) impacts include destroying ecosystems, properties and infrastructure; disrupting services; and threaten public health and cause injury and loss of life
3. Benefits of volcanic eruptions and living near volcanoes
a) volcanic eruption provides fertile soil for farming after volcanic materials are broken down and weathered, and makes available valuable minerals and building materials
b) living near volcanoes allow harnessing of geothermal energy and tourism activities
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