Summary
Tectonic processes involve the movement of Earth's plates, leading to earthquakes and volcanic activity. Understanding these processes helps explain the formation and impact of various geological features.
- Constructive (Divergent) Margins — where tectonic plates move apart, allowing magma to rise and form new crust. Example: Mid-Atlantic Ridge.
- Destructive (Convergent) Margins — where an oceanic plate subducts beneath a continental plate, causing earthquakes and forming stratovolcanoes. Example: Andes Mountain Range.
- Conservative (Transform) Margins — where plates slide past each other, causing earthquakes without forming volcanoes. Example: San Andreas Fault.
- Collision Zones — where two continental plates collide, creating fold mountains. Example: Himalayas.
- Focus (Hypocenter) — the point underground where an earthquake begins. Example: Deep within the Earth's crust.
- Epicenter — the point on the Earth's surface directly above the focus. Example: Often where the most damage occurs.
- Seismic Waves — energy waves that travel through the Earth during an earthquake. Example: P-waves and S-waves.
- Active Volcanoes — volcanoes that have erupted recently and may erupt again. Example: Mount Etna.
- Dormant Volcanoes — volcanoes that haven't erupted in centuries but could erupt again. Example: Mount Fuji.
- Extinct Volcanoes — volcanoes that are unlikely to erupt again. Example: Mount Kenya.
- Shield Volcanoes — volcanoes with gentle slopes formed by runny lava. Example: Mauna Loa.
- Strato-volcanoes (Composite Cone) — volcanoes with steep sides formed by viscous lava. Example: Mount St. Helens.
- Cinder Cones — small volcanoes formed by loose volcanic debris. Example: Parícutin.
- Lava Flows — streams of molten rock from a volcano. Example: Destroy property but rarely kill people.
- Pyroclastic Flows — fast-moving avalanches of hot gas and debris. Example: Extremely deadly and fast.
- Lahars — volcanic mudflows that can bury communities. Example: Can travel far from the volcano.
- Ash Falls — volcanic ash that can travel long distances. Example: Affects air travel and health.
- Tephra — solid material ejected during an eruption. Example: Ranges from ash to large volcanic bombs.
- Toxic Gases — harmful gases released by volcanoes. Example: Carbon dioxide and sulfur dioxide.
Exam Tips
Key Definitions to Remember
- Constructive (Divergent) Margins
- Destructive (Convergent) Margins
- Conservative (Transform) Margins
- Collision Zones
- Focus (Hypocenter)
- Epicenter
- Seismic Waves
- Active Volcanoes
- Dormant Volcanoes
- Extinct Volcanoes
- Shield Volcanoes
- Strato-volcanoes (Composite Cone)
- Cinder Cones
- Lava Flows
- Pyroclastic Flows
- Lahars
- Ash Falls
- Tephra
- Toxic Gases
Common Confusions
- Confusing focus and epicenter locations
- Mixing up magma and lava
- Believing all volcanic eruptions are explosive
- Forgetting that conservative margins have no volcanoes
Typical Exam Questions
- What type of volcano has gentle slopes and runny lava? Answer: Shield volcano.
- What's the difference between magma and lava? Answer: Magma is underground; lava is above ground.
- Why do destructive boundaries cause earthquakes? Answer: Due to friction between subducting plates.
- Which volcanic hazard is the most deadly and why? Answer: Pyroclastic flows; they are fast and hot.
- True or False: Conservative plate boundaries produce volcanoes. Answer: FALSE.
- Where is the epicenter of an earthquake located? Answer: Directly above the focus on the surface.
What Examiners Usually Test
- Understanding of different plate boundaries
- Ability to explain why earthquakes and volcanoes occur
- Knowledge of volcanic hazards and their impacts
- Differences between types of volcanoes and their eruptions