ES1 Final Quarter Exam Quiz

What is the minimum number of seismic stations required to accurately determine the epicenter of an earthquake?

• 3

• 2

• 4

• 5

Answer explanation

To accurately determine the epicenter of an earthquake, at least three seismic stations are required. Each station measures the time it takes for seismic waves to reach it, allowing triangulation of the epicenter's location.

The time interval between the arrival of P-waves and S-waves at a seismic station is used to:

• Calculate the distance to the earthquake's epicenter

• Determine the magnitude of the earthquake

• Measure the depth of the earthquake focus

• Locate the fault line

Answer explanation

The time interval between P-waves and S-waves helps determine the distance to the earthquake's epicenter, as P-waves travel faster than S-waves. This difference in arrival times is crucial for locating the earthquake's source.

Why is the epicenter not always located directly above the focus?

• Geological structures can redirect seismic energy

• Fault lines move unpredictably

• Epicenters depend on tectonic plate speed

• The Richter scale causes distortions

Answer explanation

The epicenter is not always directly above the focus because geological structures can redirect seismic energy, causing the epicenter to shift from the vertical line above the focus.

Which seismic wave causes particles to move perpendicular to the wave's direction of travel?

• S-wave

• P-wave

• Love wave

• Rayleigh wave

Answer explanation

The S-wave, or secondary wave, causes particles to move perpendicular to its direction of travel, unlike P-waves which move parallel. This characteristic makes S-waves shear waves, essential for understanding seismic activity.

What happens to P-waves as they pass through the Earth's liquid outer core?

• They slow down

• They stop completely

• They travel faster

• They bend upward

Answer explanation

As P-waves pass through the Earth's liquid outer core, they slow down due to the lower density and different physical properties of the liquid compared to the solid mantle. This is why the correct answer is 'They slow down'.

Surface waves can be divided into two main types. These are:

• Love waves and Rayleigh waves

• P-waves and S-waves

• Tensional waves and compressional waves

• Body waves and harmonic waves

Answer explanation

Surface waves are primarily classified into Love waves and Rayleigh waves, which are types of seismic waves that travel along the Earth's surface, unlike P-waves and S-waves, which are body waves.

What type of fault is most commonly associated with transform boundaries?

• Strike-slip fault

• Normal fault

• Reverse fault

• Thrust fault

Answer explanation

Transform boundaries are characterized by lateral movement of tectonic plates, which commonly results in strike-slip faults. These faults allow the plates to slide past each other horizontally, making strike-slip the correct answer.

A fold in rock layers where the youngest layers are at the center is called a:

• Syncline

• Anticline

• Monocline

• Fault scarp

Answer explanation

A syncline is a fold in rock layers where the youngest layers are at the center, creating a U-shaped structure. In contrast, an anticline has the oldest layers at the center. Therefore, the correct answer is syncline.

Which of the following is the best example of crustal deformation?

• The formation of the Himalayas due to tectonic collision

• Volcanic eruptions along the Pacific Ring of Fire

• The subduction of the Pacific Plate under the Philippine Sea Plate

• Mid-ocean ridge formation

Answer explanation

The formation of the Himalayas is a prime example of crustal deformation, as it results from the collision of tectonic plates, leading to the uplift and folding of the Earth's crust.

What type of volcanic eruption is characterized by the release of water vapor and steam, with little to no lava?

• Phreatic eruption

• Plinian eruption

• Strombolian eruption

• Pelean eruption

Answer explanation

A phreatic eruption occurs when water vapor and steam are explosively released due to the heating of groundwater, with minimal or no lava involved. This distinguishes it from other eruption types like Plinian or Strombolian.