Plate Tectonics and Earthquake Science: Key Concepts and Evidence remastered

What is the lithosphere?

The lithosphere is a rigid layer composed of the Earth's crust and the uppermost part of the mantle.

What is Plate Tectonics?

Plate Tectonics is the study of the formation and movement of large rigid pieces called plates that cover the Earth's surface.

How many major tectonic plates are there?

There are 12 major tectonic plates along with several minor plates.

What is the thickness of the lithosphere?

The lithosphere is about 100 km thick.

What type of rock makes up the oceanic crust?

The oceanic crust is primarily composed of the igneous rock basalt.

What type of rock makes up the continental crust?

The continental crust is primarily composed of the igneous rock granite.

What is the asthenosphere?

The asthenosphere is a layer of the mantle with partially melted rock that flows slowly, allowing tectonic plates to move.

What is slab pull?

Slab pull is the process where older crust dives back into the Earth, helping to pull the slab of crust apart at mid-ocean ridges.

What evidence supports the theory of continental drift?

Evidence includes the similarity of coastlines between Africa and South America, fossil evidence like Mesosaurus, and matching rock formations.

What is paleomagnetism?

Paleomagnetism is the study of the Earth's ancient magnetic field as recorded in rocks and sediments.

What is the Ring of Fire?

The Ring of Fire is a major area in the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur.

What happens to rocks as you move away from a mid-ocean ridge?

As you move away from a mid-ocean ridge, the rocks get older.

What are diverging boundaries?

Diverging boundaries are where two lithospheric plates are moving apart, such as at mid-ocean ridges.

What are transform boundaries?

Transform boundaries are where lithospheric plates slide past each other, like the San Andreas Fault.

What occurs at converging boundaries?

At converging boundaries, two lithospheric plates move towards each other, which can lead to collisions.

What geological features are formed at mid-ocean ridges?

Mid-ocean ridges form new rock and have long valleys called rift valleys.

What is the significance of coal deposits found in Antarctica?

Coal deposits in Antarctica suggest that it was once closer to the equator and had a warmer climate.

What are fracture zones?

Fracture zones are faults that break long valleys into smaller sections along mid-ocean ridges.

What is the relationship between earthquakes and tectonic plate boundaries?

Earthquakes are commonly located along tectonic plate boundaries, particularly in regions like the Ring of Fire.

What is the role of convection currents in plate movement?

Convection currents in the asthenosphere cause the lithospheric plates to move apart or collide.

What happens when continental plates collide?

They weld together to form a larger continent, resulting in features like the Himalayan Mountains.

What is an example of a continent that collided with another?

India collided with Southeast Asia.

What geological feature is formed by oceanic-ocean collisions?

A deep ocean trench and volcanic islands or island arcs.

What occurs when an older oceanic plate collides with a younger oceanic plate?

The older plate subducts beneath the younger plate, which is the overriding plate.

What is the Benioff zone?

A region where earthquakes originate deeper in the Earth's interior, particularly at subduction boundaries.

What are hotspots in geology?

Areas of volcanic activity resulting from plumes of hot material rising from deep within the Earth's mantle.

How do hotspots create islands?

As tectonic plates move over a hotspot, volcanic activity occurs, forming islands like the Hawaiian Islands.

What is the Elastic Rebound theory?

The theory explaining how stress builds up in plates until it overcomes friction, causing sudden movement and release of energy.

What is the focus of an earthquake?

The point at which the movement occurs on a fault line.

What is the epicenter of an earthquake?

The point on the Earth's surface directly above the focus.

What are Primary waves (P-waves)?

Waves that compress and stretch rock material, traveling through solids, liquids, and gases at speeds of 4-5 km/sec.

What are Secondary waves (S-waves)?

Waves that move side to side, traveling only through solids at speeds of 1-3 km/sec.

What happens to P-waves and S-waves at the outer core?

P-waves slow down greatly, while S-waves are completely stopped, indicating the presence of a liquid outer core.

What is the shadow zone in relation to earthquakes?

Areas on Earth that receive no P or S waves from an earthquake due to the outer core's properties.

What causes the shadow zone?

The absorption of S-waves by the liquid outer core and the refraction of P-waves due to different densities inside the Earth.

What is the significance of the depth of 2900 km in the Earth's interior?

At this depth, P-waves show a sharp change in velocity, indicating the transition to the outer core.

What is inferred about the composition of the Earth's outer and inner core?

They are believed to be composed of iron and nickel, based on studies of meteorites.

What geological feature is associated with the Hawaiian Islands?

They are volcanic peaks formed over a hotspot in the Pacific Plate.

What is the relationship between earthquake depth and plate boundaries?

Subduction zones have earthquakes that range from shallow to deep, while spreading centers and transform faults have more shallow earthquakes.

What is the role of friction in the buildup of stress in tectonic plates?

Friction between plates prevents movement until stress overcomes it, leading to an earthquake.

What is the process of island formation over a mantle hotspot?

As the tectonic plate moves over the hotspot, volcanic activity creates new islands while older ones become extinct.

What happens to seismic wave speeds as they travel through denser materials?

Both P-waves and S-waves increase in speed when traveling through denser materials.

What are the stages of island formation over a hotspot?

The formation includes initial volcanic activity, island growth, and eventual extinction of older islands.

How do earthquakes relate to the motion of lithospheric plates?

Earthquakes result from the release of energy due to the movement and stress between lithospheric plates.

What is the significance of the depth of 5150 km in the Earth's interior?

At this depth, P-waves increase in velocity, indicating the beginning of the solid inner core.