Volcanoes Flashcards
What is a vent in the context of volcanoes?
The opening/gap that links the surface with the Mantle
Vents are crucial for the eruption process as they allow magma to escape from the Earth’s interior.
Define a pipe in volcanic terminology.
A vertical, hardened lava found within the centre of a volcanic cone
Pipes are formed by the solidification of magma within the conduit of a volcano.
What is a crater?
A depression that can be found on the top of a volcanic cone
Craters are often formed after a volcanic eruption when the magma chamber empties.
What is a side vent?
A channel that cuts across the volcanic cone through which lava and other volcanic material can escape
Side vents can create additional outlets for volcanic activity, allowing for more complex eruption patterns.
Where is the magma chamber located?
An area found directly below the vent where magma is stored
The magma chamber is critical for storing molten rock before it erupts.
What type of volcano is Mount Fuji, Japan?
Composite Volcano
Composite volcanoes are characterized by their layered structure, consisting of both lava flows and pyroclastic material.
What is pyroclastic flow?
A fast-moving current of hot gas and volcanic matter
Pyroclastic flows are one of the most dangerous volcanic hazards due to their speed and temperature.
Name three locations where volcanoes can be found.
- Fuji, Japan
- Mount St. Helens, U.S.A
- Cotopaxi, Ecuador
Volcanoes are commonly located along tectonic plate boundaries.
True or False: Volcanoes can be found along convergent and divergent plate margins.
True
These plate boundaries are where the geological activity necessary for volcano formation occurs.
Fill in the blank: Volcanoes can be found in the Caribbean islands from _______ to _______.
18°N to 12°N
This geographical range indicates a significant presence of volcanic activity in the Caribbean.
List two volcanoes located in the Caribbean.
- La Soufrière, St. Vincent and the Grenadines
- Soufrière Hills, Montserrat
These volcanoes are notable for their recent eruptive activity.
What is a common early sign that a volcano may erupt?
Earthquake activity as minor volcanic shocks
What gases are typically associated with volcanic activity?
Various gases leak from volcanic vents
What visual signs might indicate impending volcanic activity?
Emergence of stream or smoke from existing vents and new smoking vents
What changes in local environmental conditions can signal a volcano’s eruption?
Deviations in local electric and magnetic fields
What geological changes can indicate volcanic activity?
Development of new ground cracks or widening of old ones
What instruments are used to detect changes in volcanic activity?
Tiltmeter and infrared instruments
What is the purpose of a tiltmeter in volcanic observation?
To detect variation of 1 mm change per km
What can the growth of an underground mass of molten rock indicate?
Changes in the slope of the land
What are Primary Hazards in volcanic activity?
Hazards caused by the direct eruption or emissions of a volcano
What is a Lava Flow?
Hot molten rocks that seep out onto the surface during a volcanic eruption
What are the two types of lava?
- Basic (Basaltic) Lava
- Acidic (Viscous) Lava
How fast can basic lava flow?
About 50 km per hour
Where do basic lava flows usually occur?
At Divergent Plate Boundaries
What are the characteristics of acidic lava?
Moves slowly, erupts violently, and emits poisonous gases
What historical event illustrates the dangers of lava flows?
1783 Iceland lava flows melted ice caps, causing 20% of the population to drown or starve
What temperature can lava reach?
Over 500°C
What are Pyroclastic Flows?
Mixtures of hot rock fragments, lava particles, and ash buoyed up by hot gases
How fast can pyroclastic flows move?
About 100 km/hr
What are the temperature ranges for pyroclastic flows?
200 °C - 800 °C
In what areas do pyroclastic flows typically travel?
Follow valleys or other low-lying areas
True or False: Pyroclastic flows are slower than lava flows.
False
What is a common early sign that a volcano may erupt?
Earthquake activity as minor volcanic shocks
What gases are typically associated with volcanic activity?
Various gases leak from volcanic vents
What visual signs might indicate impending volcanic activity?
Emergence of stream or smoke from existing vents and new smoking vents
What changes in local environmental conditions can signal a volcano’s eruption?
Deviations in local electric and magnetic fields
What geological changes can indicate volcanic activity?
Development of new ground cracks or widening of old ones
What instruments are used to detect changes in volcanic activity?
Tiltmeter and infrared instruments
What is the purpose of a tiltmeter in volcanic observation?
To detect variation of 1 mm change per km
What can the growth of an underground mass of molten rock indicate?
Changes in the slope of the land
What are Primary Hazards in volcanic activity?
Hazards caused by the direct eruption or emissions of a volcano
What is a Lava Flow?
Hot molten rocks that seep out onto the surface during a volcanic eruption
What are the two types of lava?
- Basic (Basaltic) Lava
- Acidic (Viscous) Lava
How fast can basic lava flow?
About 50 km per hour
Where do basic lava flows usually occur?
At Divergent Plate Boundaries
What are the characteristics of acidic lava?
Moves slowly, erupts violently, and emits poisonous gases
What historical event illustrates the dangers of lava flows?
1783 Iceland lava flows melted ice caps, causing 20% of the population to drown or starve
What temperature can lava reach?
Over 500°C
What are Pyroclastic Flows?
Mixtures of hot rock fragments, lava particles, and ash buoyed up by hot gases
How fast can pyroclastic flows move?
About 100 km/hr
What are the temperature ranges for pyroclastic flows?
200 °C - 800 °C
In what areas do pyroclastic flows typically travel?
Follow valleys or other low-lying areas
True or False: Pyroclastic flows are slower than lava flows.
False
