Natural Disasters exam 1

What provides the energy for the external processes (hurricanes, tornadoes, etc.) on Earth?

The Sun

What is the key difference between a natural hazard and a natural disaster?

A natural hazard poses a threat to human life or property, while a natural disaster results in significant death and destruction.

Which state is NOT at risk for tropical cyclones?

Idaho

What area in the United States is NOT at risk for any natural disaster?

All areas of the United States are at risk for some kind of natural disaster.

What are primary effects?

Effects that occur as a result of the process itself, such as water damage during a flood.

What is an example of a local emergency?

A small (EF1) tornado touching down with limited damage.

What defines a natural disaster?

A large tornado that causes fatalities and a State of Emergency to be declared.

Why do lightning strikes have a low potential for catastrophe?

Lightning doesn't usually affect people and property on a large scale.

What subgroup do tornadoes belong to?

Meteorological natural hazards.

What subgroup do Snow Avalanches belong to?

Geophysical natural hazards.

What does risk refer to in the context of hazards?

The way a hazard or disaster will affect human life and property.

What was NOT a factor in the high number of deaths in the 2010 Haiti earthquake?

Shallow sloping coastline allowed tsunami to surge far inland.

What is the Continental Drift Hypothesis?

A theory proposed by Alfred Wegener.

What was Alfred Wegener's supercontinent called?

Pangaea.

What evidence supports Wegener's hypothesis?

Identical fossils found on continents that are now separated by oceans.

Why was Wegener's hypothesis rejected?

He could not explain how the continents moved.

When was the Theory of Plate Tectonics developed?

After WWII.

What does magnetic reversals provide evidence for?

Seafloor spreading.

What does Plate Tectonic Theory predict about the distribution of earthquakes?

They should occur primarily along plate boundaries.

How do ocean rocks age in relation to mid-ocean ridges?

Ocean rocks get younger with increasing distance from a mid-ocean ridge.

What is the approximate age of the oldest oceanic crust?

180 million years.

What have reversals of the Earth's magnetic polarity represented?

Times when the south magnetic pole was swapped with the north magnetic pole.

Which statement is TRUE about plate tectonics?

Explains that the Earth's lithosphere is split into large pieces that move on top of a weak and hot layer called the asthenosphere.

What is associated with seafloor spreading?

All of the above options (new ocean crust is generated, continents move apart, and a record of paleomagnetic reversals is recorded).

What is true about the Mid-Atlantic Ridge?

It is a divergent boundary where tectonic plates move apart.

What is a surface expression of a mantle plume called?

Hot spot.

What kind of hazards are expected at a transform plate boundary?

Shallow earthquakes; no volcanoes.

What kind of hazards are expected at a divergent plate boundary?

Only shallow earthquakes; volcanic eruptions.

What kind of hazards are expected at a convergent plate boundary associated with a subduction zone?

Shallow, intermediate and deep earthquakes; volcanic eruptions.

Why aren't volcanoes associated with continent-continent convergence?

Continental plates are too buoyant to sink into the asthenosphere.

In an ocean-continent convergent margin, which plate subducts?

The oceanic plate subducts beneath the continental plate because it is denser.

What is a volcanic island arc?

A chain of volcanoes associated with ocean-ocean convergent plate boundaries.

Where is a new ocean basin trying to form?

The East Africa Rift Valley.

How do plates move at a transform plate boundary?

Plates move laterally past each other with horizontal motion.

What is a typical rate of seafloor spreading?

5 cm/year.

What feature is associated with volcanic eruptions and can produce a chain of extinct volcanoes?

Hotspot.

If stress is not equal from all directions, it is classified as what type of stress?

Differential stress.

What change occurs in a rock subjected to increasing differential stress?

Strain.

What stress results in shortening and thickening of rock bodies?

Compressional stress.

What type of fault is associated with horizontal motion?

Strike slip fault.

What are the three successive stages of deformation?

Elastic deformation, plastic deformation, and rupture.

What type of material is ductile?

Material that can deform easily.

What type of fault is characterized by hanging wall moving down relative to footwall?

Normal fault.

What explains why a strong underwater strike-slip fault earthquake has a low tsunami risk?

The motion during the earthquake is primarily horizontal.

What type of fault indicates a left-lateral strike slip?

Left-lateral strike slip fault.

Where are shallow-focus earthquakes found?

On all plate boundaries and within the plates.

Where are deep and ultra-deep focus earthquakes found?

Only at subduction zones.

What does Point 1 represent in an earthquake diagram?

The focus.

What is the FALSE statement about P-waves?

P-waves cause the most damage in an earthquake.

Which seismic waves are the last to reach a seismograph station?

Surface waves.

What type of seismic wave is a Rayleigh wave?

Surface wave.

According to elastic rebound theory, earthquakes occur when?

Strain on a fault is released abruptly as the fault ruptures.

What method is used to find the distance to the epicenter of an earthquake?

Comparing the arrival times of the P- and S-waves.

What distinguishes earthquake intensity from magnitude?

Intensity refers to the degree of shaking, while magnitude refers to the amount of energy released.

How much more energy does a moment magnitude 3.0 earthquake release compared to a 2.0 earthquake?

Releases 32 times more energy.

Which earthquake's ground shaking is typically greater?

An earthquake's focus/hypocenter is shallow.

How does Mexico City's construction on mud deposits affect earthquake hazard?

Earthquakes shaking will be increased.

What causes strong earthquakes in Southeast Missouri?

Intraplate earthquakes caused by ancient failed rifts.

Where are the largest earthquakes (megathrust earthquakes) found?

Convergent plate boundaries (subduction zones).

Which statement is NOT an effect of earthquakes?

Volcanic Eruptions.

Which earthquake hazard can threaten distant areas?

Tsunami.

What kind of material is prone to liquefaction during an earthquake?

Water-saturated sandy soil.

Which human activity is NOT known to cause earthquakes?

Excavating large amounts of materials to make new buildings.

Which method is NOT involved in the short-term prediction of earthquakes?

Gravitational attraction between the Moon and the Earth.

Which is NOT a practical way for communities to handle earthquake hazards?

Avoid living in an area where there are any earthquakes.

What is the most realistic approach to minimizing earthquake hazards?

Legislate strict building codes that require strong and flexible buildings.

What should someone moving to Los Angeles do regarding their home?

Secure large objects.

Does homeowner’s insurance cover earthquake damage?

No.

What type of construction should be preferred in earthquake-prone areas?

A wood house.

What is the purpose of plywood in house construction?

Bracing.

Why are earthquakes less common in seismic gaps?

The rock is locked and stores energy rather than releasing it.