Geosciences in the Movies - Plate Tectonics and Earthquakes Review

Flashcards created from lecture notes on Plate Tectonics and Earthquakes for review purposes.

What are the four layers of the Earth?

Crust, Mantle, Outer Core, Inner Core.

What is the crust composed of?

Solid, low density, cold, strong rocks.

What can cause the heat inside the Earth?

Heat from collisions, radioactive decay from when it was formed, and primordial heat.

What causes the interior of the Earth to be layered?

Heavier elements sink to form the core; lighter elements rise to form the mantle and crust.

What is the Mohovicic discontinuity?

The boundary between the crust and the mantle.

Why is the outer core liquid?

It is under less pressure, allowing it to melt.

Why is the inner core solid despite being hotter than the outer core?

It is under immense pressure, causing atoms to form solids.

Define the lithosphere.

The rigid and brittle layer comprising the crust and the uppermost mantle.

Define the asthenosphere.

The upper part of the mantle below the lithosphere that flows slowly over time.

What evidence did Wegner use for continental drift?

Puzzle-like fit of continents, fossil evidence, and geological evidence.

What is Pangaea?

A supercontinent that formed when all continents came together.

How do we know Earth's magnetic field has reversed?

Magnetic stripes on the seafloor from aligned iron-rich minerals.

What is a mid-ocean ridge?

An underwater mountain range formed where two tectonic plates are moving apart.

What occurs in a subduction zone?

Two tectonic plates collide, with one being pushed under the other.

What happens at a transform plate boundary?

Two tectonic plates slide past each other without moving apart.

What is a passive plate margin?

A place where continent and ocean meet without tectonic activity.

Define a supercontinent.

A large landmass consisting of several continents that come together.

What causes the high topography of the Himalayas?

The collision of the Indian Plate and Eurasian Plate.

What is the Wilson Cycle?

The process of forming, breaking, and reforming supercontinents.

Can convection occur within a crystalline solid?

No, convection requires fluid motion.

What drives plate tectonics?

Mantle convection.

What are the components required for Earth's magnetic field?

Molten, electrically conductive interior, convection currents, and fast rotation.

What is elastic rebound?

When the crust bends and releases energy suddenly.

What is stick-slip behavior?

Faults remain stuck while energy builds up, then slip suddenly.

What is an asperity?

A rough or stuck spot on a fault line.

How do plates deform before and during a subduction zone earthquake?

Before: one plate pushes under another, bending the overriding plate. During: stress causes a sudden slip.

Where do thrust faults occur?

In convergent settings where one plate is forced over another.

Where do normal faults occur?

In divergent settings where plates move apart.

What do strike-slip faults involve?

Plates sliding past each other horizontally.

How do movies depict earthquakes incorrectly?

They show fault lines opening into chasms and depict them as primary causes of large tsunamis.

What are body waves?

Seismic waves that travel through the Earth, including P waves and S waves.

What are Love waves?

A surface wave that travels along the Earth's surface with side-to-side motion.

What are Rayleigh waves?

A surface wave with an up-and-down rolling motion.

How many seismograms are needed to locate an earthquake?

Three seismograms.

How do we know the outer core is liquid?

S-waves cannot travel through liquids and are absent in the outer core.

What does earthquake magnitude relate to?

Intensity of shaking, measured on a logarithmic scale.

What influences earthquake intensity?

Magnitude, distance from epicenter, depth, local geology, and building quality.

Why are earthquakes felt farther away in the eastern US?

Older, denser, and more stable geology of the eastern United States.

What influences earthquake earthquake prediction?

Analyzing historical seismic activity and understanding fault behavior.

What is a precursor signal?

An indicator that may suggest an upcoming earthquake, but not always accurate.

What is the role of GPS in predicting earthquakes?

Measuring slip deficit rates to predict necessary earthquake slip.

What are some ways to minimize earthquake deaths?

Drop, cover, hold; educate the public; build earthquake-resistant structures.

How do diagonal beams help buildings?

They provide resistance to shearing forces.

What percentage of avoiding collapse is required by California building codes?

90%.

What is liquefaction?

The process where saturated soil loses strength and stiffness during shaking.

What systems can prevent excessive building sway during an earthquake?

Base isolation systems, inertial damping systems, tuned mass dampers.

How does an earthquake early warning system function?

It detects initial P-waves to provide advance notice of shaking.

What is a seismic hazard?

A measure of the potential for earthquakes in an area.

What geological feature indicates a mid-ocean ridge?

Long underwater mountain ranges.

What limits the maximum earthquake magnitude prediction?

The complex nature of stress accumulation and release in faults.

How is earthquake magnitude measured?

Using the Richter or moment magnitude scale.

What are the biggest earthquakes in history?

Chile 1960, Alaska 1964, Sumatra-Andaman 2004, Japan 2011.

How are building practices important in earthquake-prone areas?

They must be designed to withstand seismic activity.

What type of wave is fastest during an earthquake?

P waves.

What can amplify seismic shaking?

Loose sediments during an earthquake.

What is the elastic rebound theory used to explain?

The occurrence of earthquakes.

What happens to seismic waves traveling through different materials?

Their speed and behavior change based on the material.

Why is the East Coast of the US more stable?

It consists of older, denser geological formations.

What impacts do large buildings have during an earthquake?

They can sway or collapse if not properly designed.

What geological condition is indicated by the absence of S-waves?

The presence of a liquid outer core.

What role does heat play in mantle convection?

It drives the movement of mantle currents.

What is the difference between compressional and shear waves?

Compressional waves move parallel to propagation; shear waves move perpendicular.

What is the relationship between magnitude and energy release during earthquakes?

Each whole number increase in magnitude represents a 32-fold increase in energy release.

What is an important consideration for public safety during earthquakes?

Education about hazards and emergency procedures.

What does the Mercalli scale measure?

The intensity of shaking experienced during an earthquake.

What is the significance of building foundations?

Proper foundations prevent collapse during an earthquake.

What are the effects of local geology on shaking intensity?

Certain geological conditions can significantly enhance shaking.