earthquakes and volcanoes Flashcards
(30 cards)
What is plate tectonics?
Earth lithosphere (crust and upper mantle) is made of rigid plates that move due to forces in the mantle
Plate tectonics explains the movement of large sections of the Earth’s crust.
What is the outermost layer of the Earth called?
Crust
The crust is the uppermost layer of the Earth where we live.
What is the composition of continental crust?
Thick, less dense, made of granite
Continental crust is generally thicker than oceanic crust.
What is the composition of oceanic crust?
Thin, denser, made of basalt
Oceanic crust is typically thinner and denser compared to continental crust.
What layer lies beneath the crust?
Mantle
The mantle is a semi-solid rock layer where convection currents occur.
What are convection currents?
Heat from the Earth core causes molten rock in the mantle to move in circular patterns, driving plate motion
Convection currents are essential for the movement of tectonic plates.
What is found in the outer core?
Liquid iron and nickel
The outer core is responsible for the Earth’s magnetic field.
What is found in the inner core?
Solid iron and nickel
The inner core is extremely hot and under immense pressure.
What type of plate boundary occurs when oceanic and continental plates collide?
Destructive (convergent)
This type of boundary leads to phenomena such as volcanoes and earthquakes.
What geological features are associated with destructive plate boundaries?
- Volcanoes
- Earthquakes
- Fold mountains
An example is the Andes mountain range in Argentina.
What occurs at constructive (divergent) plate boundaries?
Plates move apart and magma rises to make new crust
This process creates mid-ocean ridges and rift valleys.
What is an example of a mid-ocean ridge?
Mid Atlantic Ridge
The Mid Atlantic Ridge is a prominent example of a constructive plate boundary.
What happens at transform plate boundaries?
Plates slide past each other
This movement often results in earthquakes.
What is an example of a transform fault?
San Andreas Fault
The San Andreas Fault is located in California.
What occurs when two continental plates collide?
Fold mountains are formed
An example is the Himalayas mountain range.
What is subduction?
Denser oceanic plates sink into the mantle, creating trenches and volcanic activity
Subduction zones are critical for recycling Earth’s materials.
What types of volcanoes are formed at divergent plate boundaries?
Shield volcanoes
Shield volcanoes have a wide base and gentle slopes.
What is the shape and eruption style of composite volcanoes?
Steep sided, cone shaped; eruptions are less frequent but very violent
Composite volcanoes can produce pyroclastic flows and ash clouds.
What characterizes cinder cone volcanoes?
Small, steep sided; made of loose pyroclastic material
Cinder cone volcanoes are typically the simplest type of volcano.
Fill in the blank: Earthquakes are caused by sudden movement along _______ or at plate boundaries.
faults
Faults are fractures in the Earth’s crust where movement has occurred.
What geological feature is formed by convergent continental plates?
Fold mountains
Fold mountains are created by the collision of tectonic plates.
What is a rift valley caused by?
Divergent plate boundaries
Rift valleys form when tectonic plates pull apart.
What was the magnitude of the earthquake in Nepal in 2015?
7.8
How far was the epicenter of the 2015 Nepal earthquake from Kathmandu?
80 km north
