1B1 Solid Earth Processes Flashcards
Gain an understanding of solid Earth processes: plate tectonics, volcanic activity, earthquakes, and the rock cycle.
What is the role of seismologists in studying earthquakes?
They use earthquakes / seismic waves to deduce the structure of the Earth’s interior.
How are tsunamis formed?
- Tsunamis form mainly from underwater earthquakes, which displace large volumes of water, creating waves that grow taller as they reach shallow coasts.
- They can also result from volcanic eruptions, landslides, or meteorite impacts.
Tsunamis usually form in coastal areas near subduction zones, where tectonic plates collide or slip past each other.
What causes the start of a tsunami?
A sudden violent movement of one of the tectonic plates under the ocean can displace a large amount of water, triggering the start of a tsunami.
How do tsunamis behave as they approach the shoreline?
They move quickly in the open ocean, but as they approach the shoreline, their speed slows, wavelength decreases, height increases, and currents intensify, resulting in massive destruction.
How are volcanoes formed?
- They are formed as a result of tectonic plates that are diverging, converging, or stretching and thinning.
- When plates move, magma can rise and melt the crust above, forming a volcano.
Magma is called lava once it erupts onto the surface.
How many major tectonic plates account for the continents of the world?
7
The seven major tectonic plates cover nearly 95% of the Earth’s surface.
What causes earthquakes, volcanoes, and other seismic activity in the Earth’s crust?
Convection current in the mantle.
Convection currents are caused by the heat from the Earth’s interior.
What is a tectonic plate?
A massive, irregularly shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.
What is the theory of plate tectonics?
That Earth’s outer shell is divided into several plates that glide over the mantle.
What are the three types of plate boundaries?
- Divergent boundaries
- Convergent boundaries
- Transform boundaries
Plate boundaries are regions where two tectonic plates meet.
What occurs at a divergent boundary?
Plates move apart, and new crust is created by magma pushing up from the mantle.
What happens at a convergent boundary?
Plates collide, leading to the formation of mountains, trenches, and volcanic activity.
Describe a transform boundary.
Plates slide past each other horizontally, often causing earthquakes.
What is subduction?
The process by which one tectonic plate moves under another, sinking into the mantle.
Name the supercontinent that existed 250 million years ago.
Pangaea
Pangaea was a supercontinent that included almost all the Earth’s landmasses.
What drives the movement of tectonic plates?
Heat from the Earth’s interior causing convection currents in the mantle.
What is a volcano?
An opening in Earth’s crust through which molten rock, ash, and gases are ejected.
What are the three main types of volcanoes?
- Shield
- Composite (stratovolcano)
- Cinder cone
The type of volcano is determined by its shape, eruption style, and composition.
What is magma?
Molten rock beneath Earth’s surface.
What is lava?
Molten rock that has erupted onto Earth’s surface.
What is a volcanic hotspot?
A location where volcanoes form away from plate boundaries, caused by upwelling plumes of hot mantle.
Define pyroclastic flow.
A fast-moving current of hot gas and volcanic matter.
What is a caldera?
A large volcanic crater, typically formed by a major eruption leading to the collapse of the mouth of the volcano.
Calderas can be tens of kilometers in diameter.
What is the Ring of Fire?
A major area in the Pacific Ocean where many earthquakes and volcanic eruptions occur.
What is a volcanic ash cloud?
A cloud of ash emitted during a volcanic eruption, which can affect climate and air travel.
What is an earthquake?
The shaking of the surface of the Earth resulting from a sudden release of energy in the Earth’s lithosphere.
What are seismic waves?
Waves of energy that travel through the Earth as a result of an earthquake.
What are the three main types of seismic waves?
- P-waves (primary waves)
- S-waves (secondary waves)
- Surface waves
Describe P-waves.
Primary waves that are compressional, travel fastest, and move through solids, liquids, and gases.
Describe S-waves.
Secondary waves that are shear, move slower than P-waves, and travel only through solids.
What are surface waves?
Seismic waves that travel along Earth’s surface and cause most of the damage during an earthquake.
What is a fault?
A fracture or zone of fractures between two blocks of rock, which allows the blocks to move relative to each other.
What is the epicenter of an earthquake?
The point on the Earth’s surface directly above the focus of the earthquake.
What is the focus (or hypocenter) of an earthquake?
The point within the Earth where an earthquake rupture starts.
What is the Richter scale?
A numerical scale used to measure the magnitude of earthquakes, based on the amplitude of seismic waves.
The Richter scale was named after Charles F. Richter, an American seismologist.
What is the rock cycle?
A continuous process by which rocks are created, changed, destroyed, and formed again.
The rock cycle includes the formation of igneous, sedimentary, and metamorphic rocks.
What are the three main types of rocks?
- Igneous
- Sedimentary
- Metamorphic
How is igneous rock formed?
From the cooling and solidification of magma or lava.
What are the two types of igneous rocks and where are they formed?
- Intrusive - formed inside the Earth
- Extrusive - formed on the surface
How is sedimentary rock formed?
From the accumulation and compaction of sediment.
What is lithification?
The process of turning sediment into rock through compaction and cementation, under high pressure.
How is metamorphic rock formed?
From the alteration of existing rock by heat, pressure, or chemical processes.
What is weathering?
The breakdown of rocks at Earth’s surface by physical, chemical, and biological processes.
Define erosion.
The process by which weathered rock and soil are moved from one place to another.
What is deposition?
The process by which sediments settle out of the transporting medium.
What is a mineral?
A naturally occurring, inorganic solid with a definite chemical composition and a crystalline structure.
What is a rock?
A natural substance composed of one or more minerals.
Describe the role of plate tectonics in the rock cycle.
Plate movements drive the formation and recycling of rocks, contributing to the creation of igneous, sedimentary, and metamorphic rocks.
What is the name for the movements of the tectonic plates over the liquid mantle?
Tectonic plate motion.
