6 Questions
Which of the following statements is true regarding the classification of volcanoes as active or inactive?
The historical timeline method considers a volcano active if it has erupted within the past 10,000 years.
What is the primary factor that determines the explosiveness of a volcanic eruption?
The silica content and viscosity of the magma.
Which of the following statements accurately describes the formation of volcanic belts?
Volcanic belts form along the boundaries of Earth's tectonic plates.
What is the term used to describe the molten material or rocks inside the Earth that are ejected during a volcanic eruption?
Lava
Which of the following statements accurately describes hot springs?
Hot springs are formed when groundwater heated by magma rises to the surface and collects in a natural pool.
What is the significance of detecting many small earthquakes near a volcano?
It means that the volcano is probably about to erupt.
Study Notes
Volcanic Activity
- Kanlaon in Negros Oriental and Taal Volcano are considered active volcanoes in the Philippines with high silica content, leading to explosive eruptions.
- A volcano is considered active if it has erupted in the past 10,000 years.
Volcano Classification
- Mayon volcano is classified as a composite volcano, characterized by its tall, cone-shaped formation with alternate layers of lava and ash.
Volcanic Eruptions
- The type of eruption of Mount Pinatubo is classified as Plinian.
- High silica content and high viscosity of magma lead to explosive volcanic eruptions.
- Viscosity of magma is comparable to the stickiness and thickness of syrup.
Volcanic Processes
- Lava refers to the molten material or rocks inside the Earth that are ejected during a volcanic eruption.
- The upward movement of magma triggers small earthquakes around a volcano before an eruption.
- Geologists detect these earthquakes to predict an impending eruption.
Hydrothermal Activity
- When groundwater heated by magma rises to the surface and collects in a natural pool, it forms a hot spring.
Magma Characteristics
- Silica content is the characteristic of magma that determines its explosiveness.
Test your knowledge on the classification of volcanoes based on historical timeline, silica content, eruption records, and composite structures. Learn about volcanic belts, active vs inactive volcanoes, and different methods to determine the activity level of a volcano.
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