Mid-Ocean Ridge and Sea Floor Spreading

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Which seismic waves are the most damaging of all the seismic waves?

S-waves
Rayleigh waves (correct)
P-waves
Love waves

What is the fastest type of seismic wave?

S-waves
Rayleigh waves
Love waves
P-waves (correct)

What is the seismic wave type that moves across the surface like a wave in the ocean?

P-waves
S-waves
Love waves
Rayleigh waves (correct)

Which scale is most useful for measuring mid-range earthquakes?

Richter Scale (B) Signup and view all the answers

What type of seismic wave is more damaging than P-waves?

S-waves (C) Signup and view all the answers

How do geologists measure the strength of earthquakes?

Seismographs (D) Signup and view all the answers

What is the main cause of fires during earthquakes?

All of the above (D) Signup and view all the answers

What is the main difference between magma and lava?

Magma is under the crust, while lava is above the crust (C) Signup and view all the answers

Which type of volcano is the most explosive?

Composite cone (D) Signup and view all the answers

What is the main effect of sulfur dioxide aerosols from volcanic eruptions?

They reflect the sun's rays into space (A) Signup and view all the answers

What is the main component of lava?

All of the above (D) Signup and view all the answers

What is the relationship between the amount of silica in lava and its viscosity?

The more silica, the higher the viscosity (C) Signup and view all the answers

What are the three types of morphologies associated with mafic lava flows?

Pahoehoe, Aa, and pillow (B) Signup and view all the answers

What differentiates nuee ardente flow from pumice flow deposits?

Nuee ardente has block-and-ash flow while pumice is a pyroclastic surge (A) Signup and view all the answers

What is the primary distinguishing feature of intermediate lava?

Blocky morphologies (A) Signup and view all the answers

How are pyroclastic surges different from pyroclastic flows?

Surges have higher gas content and lower rock fragments than flows (D) Signup and view all the answers

How do volcanic plateaus form?

From thick, easily flowing lava spreading over a wide area (D) Signup and view all the answers

What process is responsible for the formation of the Mid-Ocean Ridge?

Sea floor spreading (D) Signup and view all the answers

What is the pattern observed in the magnetic polarity of the oceanic crust near the Mid-Ocean Ridge?

The polarity alternates between normal and reversed as you move away from the ridge (D) Signup and view all the answers

What conclusion did scientists draw from the alternating pattern of magnetic polarity in the oceanic crust?

The Earth's magnetic field has flip-flopped over the years (C) Signup and view all the answers

Which of the following statements about earthquakes is true?

Earthquakes can occur both on land and underwater (B) Signup and view all the answers

Which of the following is NOT a type of fault mentioned in the text?

Thrust fault (D) Signup and view all the answers

What can underwater earthquakes potentially trigger?

Tsunamis (C) Signup and view all the answers

What percentage of the world's volcanoes are located along the Ring of Fire?

75% (B) Signup and view all the answers

Which of the following is NOT considered a volcanic hazard?

Tephra (A) Signup and view all the answers

What is the key difference between pyroclastic flows and pyroclastic surges?

Both a and b are correct. (A) Signup and view all the answers

What is a lahar?

A landslide of volcanic debris and water (C) Signup and view all the answers

Which of the following is the LEAST deadly volcanic hazard?

Lava flows (C) Signup and view all the answers

What can cause a volcanic earthquake?

Both a and b are correct (A) Signup and view all the answers

What is the best preventative measure for protecting against lahars?

Evacuating people and developing a warning system (C) Signup and view all the answers

How can a tsunami be triggered by volcanic activity?

By the volcanic earthquake shaking the ocean floor (A) Signup and view all the answers

What is the main difference between a foreshock and a mainshock?

A foreshock is a smaller quake that occurs before the mainshock, while the mainshock is the largest quake in the series. (A) Signup and view all the answers

What is the main difference between the Richter scale and the moment magnitude scale?

The Richter scale uses the value of the amplitude of the highest seismic wave, while the moment magnitude scale uses the seismic moment to measure intensity. (A) Signup and view all the answers

How does the energy released by earthquakes increase as the magnitude on the Richter scale increases?

The energy released increases by a factor of 1,048,576 from a magnitude 4 to a magnitude 8 earthquake. (D) Signup and view all the answers

What is one of the main effects that an earthquake can have on the landscape?

Earthquakes can cause the ground to liquefy, where wet soil and sediment move and act like a liquid. (A) Signup and view all the answers

What is one of the main effects that an earthquake can have on human-made structures?

Earthquakes can cause power and gas lines to rupture, leading to widespread power outages and fires. (A) Signup and view all the answers

What is the main process responsible for the formation of the Mid-Ocean Ridge?

Sea floor spreading (C) Signup and view all the answers

What pattern is observed in the magnetic polarity of the oceanic crust near the Mid-Ocean Ridge?

The polarity alternates between normal and reversed (B) Signup and view all the answers

What is the main conclusion that scientists drew from the alternating pattern of magnetic polarity in the oceanic crust?

The Earth's magnetic field has reversed direction multiple times (A) Signup and view all the answers

What is the main effect that an underwater earthquake can have?

Cause a tsunami (B) Signup and view all the answers

What are the three main types of faults mentioned in the text?

Reverse, normal, and strike-slip (D) Signup and view all the answers

What is the main cause of earthquakes according to the text?

Plate tectonics (D) Signup and view all the answers

What is the most common gas emitted during a volcanic eruption?

Water vapor (B) Signup and view all the answers

How does the viscosity of lava relate to its silica content?

Higher silica content leads to higher viscosity (C) Signup and view all the answers

What is one of the main negative effects of sulfur dioxide released during volcanic eruptions?

It causes acid rain (A) Signup and view all the answers

What is the main difference between magma and lava?

Magma is underground, while lava is on the surface (A) Signup and view all the answers

Which of the following is NOT a type of volcanic eruption mentioned in the text?

Phreatic (D) Signup and view all the answers

What is the primary effect of carbon dioxide released during volcanic eruptions?

It is a greenhouse gas that traps heat (D) Signup and view all the answers

What is the source of seismic waves during an earthquake?

The release of stress or pressure at the fault rupture (A) Signup and view all the answers

What type of seismic waves travel through the interior of the Earth?

P-waves and S-waves (D) Signup and view all the answers

What is the term used to describe the location on Earth's surface directly above the focus of an earthquake?

Epicenter (B) Signup and view all the answers

Which of the following regions is NOT mentioned as one of the three major areas where most earthquakes occur?

The Mid-Atlantic Ridge (C) Signup and view all the answers

What is the term used to describe the mechanism or device used to measure seismic activity during an earthquake?

All of the above (D) Signup and view all the answers

What is the primary cause of most earthquakes, according to the text?

The slipping of tectonic plates (A) Signup and view all the answers

What is the difference between a foreshock and an aftershock?

A foreshock is a smaller quake that occurs before the mainshock, while an aftershock is a smaller quake that occurs after the mainshock. (C) Signup and view all the answers

What is the relationship between the magnitude of an earthquake and the amount of ground shaking?

As the magnitude increases, the amount of ground shaking increases exponentially. (A) Signup and view all the answers

Which scale is better suited for measuring the magnitude of large earthquakes?

The moment magnitude scale (C) Signup and view all the answers

What is the primary function of a seismograph?

To detect seismic activity and measure the amplitude of seismic waves (A) Signup and view all the answers

What is the main cause of structural damage during an earthquake?

Ground shaking (D) Signup and view all the answers

Which of the following is NOT a potential effect of an earthquake?

Volcanic eruptions (A) Signup and view all the answers

What is the primary factor that determines the viscosity of lava?

Silica content of the lava (D) Signup and view all the answers

Which of the following is NOT a characteristic of pyroclastic flows?

They move very slowly (D) Signup and view all the answers

What is the primary difference between a nuee ardente flow and a pumice flow?

Nuee ardente flows have a higher density of lava fragments (D) Signup and view all the answers

What is the primary distinguishing feature of felsic lava?

It explodes from lava domes (D) Signup and view all the answers

What is the primary mechanism responsible for the formation of a volcanic pipe?

Pressure buildup in a magma chamber (B) Signup and view all the answers

What is the primary difference between a crater and a caldera?

A caldera is a large crater formed by the emptying of a magma chamber (D) Signup and view all the answers

Which region is known for having a high concentration of volcanoes?

The Ring of Fire (B) Signup and view all the answers

Which of the following is NOT considered a volcanic hazard?

Earthquakes (A) Signup and view all the answers

What is the main difference between pyroclastic flows and pyroclastic surges?

Pyroclastic surges contain more gas than pyroclastic flows (D) Signup and view all the answers

What is a lahar?

A flowing mass of volcanic debris and water (B) Signup and view all the answers

How can a tsunami be triggered by volcanic activity?

By a landslide (B) Signup and view all the answers

What is the main reason that lava flows are considered less deadly than other volcanic hazards?

They move at slower speeds (A) Signup and view all the answers

What is the primary reason that pyroclastic surges are considered deadly?

The presence of highly heated toxic gases (D) Signup and view all the answers

What is the main concern associated with tephra?

It can negatively impact respiratory health (C) Signup and view all the answers

What percentage of the world's volcanoes are located along the Ring of Fire?

75% (C) Signup and view all the answers

What is the best preventative measure for protecting against lahars?

Evacuating people and developing a warning system (B) Signup and view all the answers

Most damaging seismic wave

Rayleigh waves are surface waves that cause significant ground motion, making them the most damaging type of seismic wave.

Fastest seismic wave

P-waves, or primary waves, are the fastest seismic waves and travel through the Earth's interior.