Podcast
Questions and Answers
What was the approximate elevation change of Helen's summit after the eruption?
What was the approximate elevation change of Helen's summit after the eruption?
What is characterized by extremely fast-moving flows of lava, hot rocks, and gas?
What is characterized by extremely fast-moving flows of lava, hot rocks, and gas?
What phenomenon turned daylight into darkness during the eruption?
What phenomenon turned daylight into darkness during the eruption?
How much lava was discharged in the form of pyroclastic flows and surges during the eruption?
How much lava was discharged in the form of pyroclastic flows and surges during the eruption?
Signup and view all the answers
What type of damage was caused by the pyroclastic flow and surges?
What type of damage was caused by the pyroclastic flow and surges?
Signup and view all the answers
What was the primary impact of lahars flowing into the Toutle and Cowlitz rivers?
What was the primary impact of lahars flowing into the Toutle and Cowlitz rivers?
Signup and view all the answers
How far was the material transported by mudflows into the Columbia River?
How far was the material transported by mudflows into the Columbia River?
Signup and view all the answers
What was one of the significant physical impacts on nearby villages during the eruption?
What was one of the significant physical impacts on nearby villages during the eruption?
Signup and view all the answers
What geological feature is primarily formed by the process of seafloor spreading?
What geological feature is primarily formed by the process of seafloor spreading?
Signup and view all the answers
Which type of tectonic plate boundary occurs when two continental crusts move apart?
Which type of tectonic plate boundary occurs when two continental crusts move apart?
Signup and view all the answers
What is the primary mechanism that causes an oceanic plate to descend beneath a continental plate at a convergent boundary?
What is the primary mechanism that causes an oceanic plate to descend beneath a continental plate at a convergent boundary?
Signup and view all the answers
What type of magma is primarily produced when an oceanic plate subducts under a continental plate?
What type of magma is primarily produced when an oceanic plate subducts under a continental plate?
Signup and view all the answers
What occurs due to the friction and heat when an oceanic plate descends into the asthenosphere?
What occurs due to the friction and heat when an oceanic plate descends into the asthenosphere?
Signup and view all the answers
Which geological structure is commonly associated with the process of seafloor spreading?
Which geological structure is commonly associated with the process of seafloor spreading?
Signup and view all the answers
What is a significant outcome of magma moving up through breaks in the continental plate?
What is a significant outcome of magma moving up through breaks in the continental plate?
Signup and view all the answers
What geological event can result from the movement and interaction of tectonic plates at boundaries?
What geological event can result from the movement and interaction of tectonic plates at boundaries?
Signup and view all the answers
What type of plate movement is characterized by plates sliding past each other?
What type of plate movement is characterized by plates sliding past each other?
Signup and view all the answers
Which of the following features is primarily formed by divergent movement between continental plates?
Which of the following features is primarily formed by divergent movement between continental plates?
Signup and view all the answers
In which of the following locations would you expect transform plate boundaries?
In which of the following locations would you expect transform plate boundaries?
Signup and view all the answers
Which tectonic activity is NOT associated with divergent plate movements?
Which tectonic activity is NOT associated with divergent plate movements?
Signup and view all the answers
What is a common outcome of transform plate boundaries?
What is a common outcome of transform plate boundaries?
Signup and view all the answers
What occurs when a denser oceanic plate converges with a lighter continental plate?
What occurs when a denser oceanic plate converges with a lighter continental plate?
Signup and view all the answers
Which geological feature is formed where an oceanic plate dips into the asthenosphere?
Which geological feature is formed where an oceanic plate dips into the asthenosphere?
Signup and view all the answers
What type of magma is produced when the tip of the subducting oceanic plate melts?
What type of magma is produced when the tip of the subducting oceanic plate melts?
Signup and view all the answers
What causes the vibrations known as earthquakes along the subduction zone?
What causes the vibrations known as earthquakes along the subduction zone?
Signup and view all the answers
What happens to the magma as it moves upwards through fractures on the overriding oceanic plate?
What happens to the magma as it moves upwards through fractures on the overriding oceanic plate?
Signup and view all the answers
Which force is primarily responsible for the subduction of the oceanic plate?
Which force is primarily responsible for the subduction of the oceanic plate?
Signup and view all the answers
What do the gases in the magma do as it rises towards the surface?
What do the gases in the magma do as it rises towards the surface?
Signup and view all the answers
Which process occurs when lava escapes through vents on the oceanic crust?
Which process occurs when lava escapes through vents on the oceanic crust?
Signup and view all the answers
What primarily determines the geographical distribution of volcanoes in the world?
What primarily determines the geographical distribution of volcanoes in the world?
Signup and view all the answers
Which of the following plates is NOT considered a major tectonic plate?
Which of the following plates is NOT considered a major tectonic plate?
Signup and view all the answers
Which direction would you generally travel to reach volcanoes from the North American Plate?
Which direction would you generally travel to reach volcanoes from the North American Plate?
Signup and view all the answers
What is a common characteristic of regions with high volcanic activity?
What is a common characteristic of regions with high volcanic activity?
Signup and view all the answers
Which of the following minor plates is located near the Caribbean region?
Which of the following minor plates is located near the Caribbean region?
Signup and view all the answers
Where would you expect to find the majority of earthquakes in relation to tectonic plates?
Where would you expect to find the majority of earthquakes in relation to tectonic plates?
Signup and view all the answers
Which plate is located northwest of the Pacific Plate?
Which plate is located northwest of the Pacific Plate?
Signup and view all the answers
What is the relationship between tectonic plate boundaries and the occurrence of volcanoes?
What is the relationship between tectonic plate boundaries and the occurrence of volcanoes?
Signup and view all the answers
Study Notes
Mount St. Helens Eruption
- Summit elevation was approximately 2,950m before the eruption and declined to about 2,600m afterward.
- The eruption covered at least 4 square kilometers.
- Pyroclastic flows, extremely fast-moving flows of lava, hot rocks, and gas, ploughed down the mountainside.
- Pyroclastic surges, fast-moving clouds of hot ash, accompanied the pyroclastic flows.
- Between 4-5 million cubic meters of lava were released as pyroclastic flows and surges.
- The eruption caused extensive damage, destroying hundreds of homes, buildings, and infrastructure (roads, railways).
- Lahars (mudflows) flowed into the Toutle and Cowlitz Rivers, damaging approximately 35 bridges.
- 3 million cubic meters of material were transported 17 miles (27km) into the Columbia River by mudflows.
Plate Tectonics
- Seafloor spreading: Magma cools and solidifies to form new seafloor.
- Mid-Atlantic Ridge: A divergent plate boundary where younger rocks are found closer to the ridge and older rocks farther away.
- Iceland is located on the Mid-Atlantic Ridge, experiencing both volcanic and tectonic activity. Surtsey Island's formation is a notable example.
- Silfra fissure in Iceland is a visible example of a tectonic plate boundary where you can snorkel.
Continental-Continental Divergence
- Two continental crusts moving apart create tectonic faults.
- The central block lowers relative to adjacent blocks.
- Magma escaping to the surface causes volcanic activity.
- Earthquakes occur due to plate movement.
Convergent Plate Boundaries
- Continental-Oceanic: A denser oceanic plate subducts beneath a continental plate, forming an oceanic trench. Earthquakes and volcanism occur due to friction and melting of the subducting plate. The Andes Mountains and Peru-Chile Trench exemplify this.
- Oceanic-Oceanic: A denser oceanic plate subducts under another, creating an oceanic trench and volcanic island arcs.
Plate Movement Summary Table (To be completed by the student based on the provided text)
- This table would be created by the student and should include columns for: Type of Plate Movement (e.g., Divergent, Convergent-Oceanic/Oceanic, Convergent-Continental/Oceanic, Transform), Resultant Landforms/Features (e.g., Rift Valley, Oceanic Trench, Volcanic Arc, etc.), and Tectonic Activities (e.g., Earthquakes, Volcanism).
Global Distribution of Volcanoes, Trenches, and Earthquakes
- Volcanoes, trenches, and earthquakes are predominantly located along plate boundaries. A map would be useful for visualizing this global distribution. The provided EduGIS link is helpful for this purpose. Transform plate movements exhibit a side-to-side motion, also resulting in earthquakes.
Divergent Movement and Rift Valleys
- Divergent movement between continental plates results in the formation of rift valleys. An animation is linked in the text for further illustration.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the dramatic events of the Mount St. Helens eruption, including its effects on the landscape and infrastructure. This quiz also delves into the basics of plate tectonics, including seafloor spreading and geological formations like the Mid-Atlantic Ridge.
