Earthquakes and Volcanoes

Question 1

How does the location of major earthquakes and volcanoes relate to plate boundaries

Answer 1

Plates rip apart at a divergent plate boundary, causing volcanic activity and shallow earthquakes
At a convergent plate boundary, one plate dives or “subducts” beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate
At transform boundaries the plates rub against each other, huge stresses can cause portions of the rock to break, resulting in earthquakes.

Question 2

What are the different types of seismic waves

Answer 2

P-Waves (Primary Waves)
S-Waves (Secondary Waves)
Surface Waves

Question 3

Explain the difference between a seismograph and seismogram

Answer 3

A seismograph is the instrument that detects and records seismic waves, while a seismogram is the graphical representation of the recorded ground motion produced by the seismograph.

Question 4

What is the epicentre

Answer 4

The epicenter is the point on the Earth’s surface directly above the focus (hypocenter) of an earthquake.

Question 5

What is the focus

Answer 5

The focus is the actual point within the Earth where an earthquake originates.

Question 6

What is the Richter scale

Answer 6

Measures quake magnitude via logarithmic scale. Developed by Charles F. Richter in 1935. Each whole number rise = 10x amplitude, about 31.6x energy.

Question 7

What are body waves

Answer 7

There are two main types of body waves:
P-Waves
S-Waves

Question 8

What are primary waves

Answer 8

Can travel through solids and liquids
Are the fastest type of waves
Longitudinal (vibrations are along the same direction as the direction of wave)
The crust vibrates forward and back along the path of the wave

Question 9

What are secondary waves

Answer 9

Can only travel through solids
Arrive at the detectors second
Transverse (Vibrations are at right angles to the direction of travel/ vibrate up and down)
The crust vibrates from side to side and up and down

Question 10

What are surface waves

Answer 10

There are two main types of surface waves:
Love Waves
Rayleigh Waves

Surface waves typically have larger amplitudes and longer wavelengths compared to body waves (P-waves and S-waves)

Similar to water waves and travel just under the Earth’s surface
Generated when the source of the earthquake is close to the Earth’s surface
Travel the slowest
Most destructive type of seismic wave

Question 11

What are Rayleigh waves

Answer 11

Rayleigh waves: Rayleigh waves produce both vertical and horizontal ground motion. They have an elliptical rolling motion that creates an up-and-down as well as a side-to-side movement.

Question 12

What are love waves

Answer 12

Love waves: Love waves cause horizontal shaking in a side-to-side (horizontal) motion. They move in a horizontal plane parallel to the Earth’s surface.

Question 13

Define Amplitude

Answer 13

Amplitude is the height of a wave’s peak or trough from its resting position. In seismic waves, it shows the intensity of ground motion or shaking, with larger amplitude indicating stronger waves.

Question 14

List all the main features of a volcano

Answer 14

Magma Chamber, main vent, side vent, crater, ash cloud, lava bomb

Question 15

Differentiate between shield and composite volcanoes

Answer 15

In summary, shield volcanoes have wide, gentle slopes, effusive eruptions with basaltic lava, and include Mauna Loa. Composite volcanoes are steep, built from layers, have explosive eruptions with viscous lava, and include Mount St. Helens.

Question 16

What are shield volcanoes and list their features

Answer 16

Shield volcanoes are large, gently sloping volcanic structures formed by the accumulation of basaltic lava flows. They typically have non-explosive eruptions and are associated with hotspots and divergent plate boundaries.

Question 17

What are composite volcanoes and list their features

Answer 17

Composite volcanoes are tall, steep-sided volcanic mountains formed from layers of lava, ash, and pyroclastic material. They are associated with convergent plate boundaries and are characterized by explosive eruptions and a distinctive conical shape.

Question 18

What is the difference between lava and magma

Answer 18

Magma is molten rock beneath the Earth’s surface, while lava is molten rock that has erupted onto the surface during a volcanic event.

Question 19

Describe and compare active, dormant and extinct volcanoes

Answer 19

Active volcanoes are currently erupting or showing recent activity
Dormant volcanoes haven’t erupted for over 20 years but might do so in the future
Extinct volcanoes haven’t erupted for thousands of years and are unlikely to erupt again