Seismic Waves and Plate Tectonics

The video tutorial covers various aspects of the lithosphere and earth structure, including measuring the thickness of the continental lithosphere, understanding different types of plate boundaries and faults, and explaining the formation of orogenic belts. It also delves into earthquake patterns, the causes of seismic activity, and the composition of magma, particularly andesitic magma, and its role in volcanic eruptions. Additionally, the tutorial provides an analysis of seismic waves, including P waves and S waves, and their behavior as they travel through different layers of the Earth.

What is the acceptable range for the maximum thickness of the continental lithosphere?

• 100 to 110 kilometers

• 150 to 160 kilometers

• 136 to 144 kilometers

• 120 to 130 kilometers

How is the percentage increase in thickness of the continental lithosphere calculated?

• (Original thickness / Present thickness) * 100

• (Present thickness + Original thickness) / 2

• (Original thickness - Present thickness) / Present thickness * 100

• (Present thickness - Original thickness) / Original thickness * 100

Which type of fault is characterized by a low angle and the hanging wall moving up?

• Thrust fault

• Strike-slip fault

• Reverse fault

• Normal fault

Why do plates not subduct at certain orogenic belts?

• Plates are oceanic

• Plates are too thin

• Plates have equal density and are both continental

• Plates are moving apart

What is the direction of plate movement at a mid-ocean ridge?

• Southwest-Northeast

• Northwest-Southeast

• North-South

• East-West

What causes the earthquakes in subduction zones?

• Tectonic uplift

• Rising magma

• Volcanic eruptions

• Friction between plates

Why is andesitic magma more explosive than basaltic magma?

• Lower silica content

• Higher viscosity

• Lower gas content

• Higher temperature

What is the main reason S waves have a higher mean velocity at deeper levels?

• Decreased pressure

• Decreased temperature

• Increased rigidity

• Increased density

What is the significance of the shadow zone in seismic wave analysis?

• It is the point of origin for earthquakes

• It shows the highest amplitude of waves

• It is where all waves are absorbed

• It indicates the presence of a liquid outer core

How do P waves differ in arrival time compared to S waves at distant seismograms?

• P waves arrive earlier than S waves

• P waves arrive later than S waves

• P waves and S waves arrive simultaneously

• P waves do not arrive at distant seismograms