EAPS 106 Exam 1 Purdue

Exam 1 study guide and answers for EAPS 106 at Purdue University

What are the Earth's interior layers and which is the thickest/thinnest?

The Earth has three main layers: the crust (thinnest), mantle, and core (thickest).

What is a solar nebula?

A solar nebula is a cloud of gas and dust in space from which the solar system formed.

Where does the heat come from that causes new planets to be extremely hot inside?

Heat comes from gravitational compression, radioactive decay, and residual heat from formation.

Why is the inner core hotter than the outer core yet solid?

The inner core is under immense pressure, preventing it from melting despite high temperatures.

Why is the interior of the Earth layered?

The Earth's interior is layered due to the varying densities of materials, leading to differentiation.

What does plate tectonics mean?

Plate tectonics is the theory explaining the movement of the Earth's lithosphere on the asthenosphere.

What is the lithosphere?

The lithosphere is the rigid outer layer of the Earth, composed of the crust and upper mantle.

What is the asthenosphere?

The asthenosphere is the semi-fluid layer beneath the lithosphere, allowing tectonic plates to move.

Why does the hotter mantle beneath the asthenosphere not flow as easily?

Higher pressure increases viscosity, making it more resistant to flow despite higher temperatures.

What evidence of continental drift did Alfred Wegener cite?

Wegener cited fossil distributions, matching coastlines, and geological similarities.

Why did few scientists accept Wegener’s theory of continental drift?

Wegener lacked a mechanism to explain how continents moved.

What is a magnetic reversal?

A magnetic reversal is when the Earth's magnetic field changes direction.

How do we know that our magnetic field has reversed itself many times through Earth’s past?

Magnetic striping on the ocean floor records pattern reversals.

What did magnetic reversals observed on the ocean floor reveal about ocean plates?

They revealed that ocean plates are created at mid-ocean ridges and move apart.

What is a mid-ocean ridge?

A mid-ocean ridge is an underwater mountain range formed by tectonic plate divergence.

What is a subduction zone?

A subduction zone is an area where one tectonic plate descends beneath another.

What is a transform plate boundary?

A transform plate boundary is where two tectonic plates slide past each other horizontally.

What kind of plate boundary is the San Andreas Fault?

The San Andreas Fault is a transform plate boundary.

Where does Hawaii lie in terms of plate boundaries?

Hawaii does not lie on a plate boundary; it is a hot spot.

How might plate tectonics have led to the evolution of whales and dolphins from land mammals?

Plate tectonics created geographic barriers and led to the isolation of populations.

How does conduction transfer heat?

Conduction transfers heat through direct contact between materials.

How does convection transfer heat?

Convection transfers heat through the movement of fluids based on temperature differences.

How does radiative heat transfer work?

Radiative heat transfer occurs through electromagnetic waves.

In what circumstance can a solid convect?

A solid can convect if it is heated unevenly and can deform, such as in some geological contexts.

What drives plate tectonics?

Plate tectonics is driven by mantle convection, slab pull, and ridge push.

What causes a magnetic field to be produced?

A magnetic field is produced by the movement of molten iron in the Earth's outer core.

How is a permanent magnet created?

A permanent magnet is created by aligning the magnetic domains of materials.

How can an induced magnetic field generated by an electrical current be made stronger?

An induced magnetic field can be made stronger by increasing the current flow.

How does Earth generate its magnetic field?

Earth generates its magnetic field through the dynamo effect caused by the motion of molten iron.

What is notable about the magnetic pole in Earth's northern hemisphere?

The magnetic pole in the northern hemisphere is actually a south magnetic pole.

What protects us from the radiation of the Sun's solar wind?

The Earth's magnetic field protects us from solar wind radiation.

What causes the aurora lights?

Aurora lights are caused by charged particles from the solar wind interacting with the Earth's magnetic field.

How do we know the Earth is not hollow?

Seismic studies show that Earth has layers with varying densities, indicating it is not hollow.

What type of volcanic eruption brings diamonds to the surface?

Kimberlite eruptions bring diamonds to the surface.

About how many total earthquakes of any size occur globally each year?

Approximately 1.3 million earthquakes occur globally each year.

What is the largest earthquake to occur on Earth over the past 100 years?

The largest earthquake was the 2004 Sumatra-Andaman earthquake.

On average, how often do large earthquakes (≥M7.5) occur on the San Andreas Fault?

Large earthquakes on the San Andreas Fault occur approximately every 150 years.

Where do most earthquakes occur?

Most earthquakes occur along tectonic plate boundaries.

What is the concept of elastic rebound?

Elastic rebound describes how energy is released during an earthquake when rocks return to their original shape.

What is the concept of stick-slip behavior?

Stick-slip behavior refers to the alternating phases of resistance and slippage along a fault.

What are the rough parts of a fault that prevent slippage until they break called?

These rough parts are called asperities.

How do we observe the buildup of stress on a fault?

We observe the buildup of stress through strain accumulation and geological monitoring.

In which direction does Japan move between and during earthquakes?

Japan moves in a northwest direction due to tectonic plate interactions.

Where do thrust faults occur?

Thrust faults typically occur in convergent plate boundaries, where plates collide.

Where do normal faults occur?

Normal faults occur in divergent plate boundaries, where tectonic plates pull apart.

Where do transform (strike-slip) faults occur?

Transform faults occur where tectonic plates slide past each other horizontally.

What is true about gaps during earthquakes?

Faults do not open gaps during earthquakes; they release stress and slip along the fault.

What is an earthquake hypocenter?

The earthquake hypocenter is the point inside the Earth where an earthquake originates.

What are the different types of seismic waves?

The different types of seismic waves are P-waves, S-waves, and surface waves.

What are characteristics of P waves?

P waves are compressional waves that travel fastest and can move through solids and liquids.

What are characteristics of S waves?

S waves are shear waves that travel slower than P waves and can only move through solids.

What are characteristics of surface waves?

Surface waves travel along the Earth's surface and typically cause the most damage during an earthquake.

How are seismograms used to locate an earthquake?

Seismograms are analyzed to determine the time difference between P waves and S waves to locate the epicenter.

What does reflection seismology allow us to visualize?

Reflection seismology allows us to visualize subsurface geological structures.

What does earthquake seismology allow us to visualize?

Earthquake seismology allows us to understand the properties and behaviors of the Earth's interior.

How do we know that the outer core of the Earth is liquid?

We know the outer core is liquid due to the behavior of seismic waves, which do not travel through liquids.

How much does the amount of shaking vary between different magnitude earthquakes?

The amount of shaking increases exponentially with each unit increase in magnitude.

What is true about smaller magnitude earthquakes?

Smaller magnitude earthquakes occur more often than larger ones.

What is the theoretical maximum magnitude earthquake that can occur?

The theoretical maximum magnitude earthquake is around 10.

What is the relationship between the magnitude of an earthquake and its duration?

Higher magnitude earthquakes tend to last longer than lower magnitude earthquakes.

How does geology influence earthquake shaking?

Geology influences earthquake shaking through material properties like density and elasticity.

What do Mercalli intensities measure?

Mercalli intensities measure the intensity of shaking experienced during an earthquake.

What do Mercalli intensities enable us to infer about earthquakes?

They enable us to infer the effects and damage caused by earthquakes.

Why does the US Geological Survey believe there is a high seismic hazard in the Midwest?

There are historical quake records and active faults despite being far from plate boundaries.

What is true about active faults in Indiana?

Despite being far from a plate boundary, there are active faults in Indiana.

What is true about the biggest magnitude earthquakes?

The biggest magnitude earthquakes are generally not the deadliest because they may occur in unpopulated areas.

What is the timeframe we can be 90% sure that a large earthquake will occur on a particular fault?

On average, a timeframe of 30 years is needed to project a 90% certainty of a large earthquake.

Why are earthquakes so difficult to predict?

Earthquakes are difficult to predict due to the complex nature of stress accumulation and fault behavior.

What is true about earthquake precursors?

There are no reliable earthquake precursors that can be consistently observed.

What did instrumentation show just before the 2004 Parkfield earthquake?

Instrumentation showed increased seismic activity and strain accumulation.

What is the difference between foreshocks and aftershocks?

Foreshocks occur before the main earthquake, while aftershocks occur after.

What is true about a series of small earthquakes?

A series of small earthquakes does not necessarily lead to a big earthquake.

Why were seismologists in Italy jailed in 2012?

They were jailed for underestimating the risk of a significant earthquake.

What are earthquake forecasts based on?

Earthquake forecasts are based on statistical analysis of past seismic activity.

How can GPS measurements of surface deformation help estimate earthquake potential?

GPS measurements track ground movement and stress accumulation, indicating potential earthquake zones.

What should you do during an earthquake in a building?

You should stay inside, drop, cover, and hold on during an earthquake.

What should you do if on a high floor in a building during an earthquake?

You should stay in place, avoid windows, and protect your head and neck.

How does an earthquake early warning system work?

It detects initial seismic waves and sends alerts before damaging waves arrive.

How long after surface waves arrive do poorly constructed buildings generally collapse?

Poorly constructed buildings typically collapse within seconds after surface waves arrive.

What buildings collapsed disproportionately during the 2008 Wenchuan, China Earthquake?

Poorly designed and constructed buildings collapsed disproportionately during the earthquake.

What is the required percent chance of avoiding collapse during a California earthquake?

Buildings are designed to have a 95% chance of avoiding collapse.

What is forced resonance?

Forced resonance occurs when a structure vibrates in response to external forces that match its natural frequency.

Why do diagonal beams help buildings resist earthquakes?

Diagonal beams provide structural support and rigidity, helping to distribute forces.

What is true about corner studs in buildings?

The addition of simple corner studs can greatly improve building stability during earthquakes.

What is the importance of a strong foundation for earthquake resistance?

A strong foundation is crucial for stability and helps prevent collapse during earthquakes.

What is liquefaction?

Liquefaction is the process where saturated soil temporarily loses strength and behaves like a liquid during an earthquake.

How does an earthquake isolation system work?

An earthquake isolation system absorbs and reduces ground motion impacts on structures.