Volcanoes and Earthquakes

Question 1

What is a vent?

Answer 1

The opening in the volcano from where the lava comes out

Question 2

What is the summit?

Answer 2

The highest point

Question 3

What is the throat?

Answer 3

Conduits part that ejects lava and volcanic ash

Question 4

What is the conduit?

Answer 4

The passge in the volcano through which magma travels up

Question 5

What is the sill?

Answer 5

A flat peice of rock which forms by hardening of magma in a crack in a volcano.

Question 6

Where are the main location of volcanoes?

Answer 6

Most are found at the edges of tectonic plates, some lie over hotspots
Can happen at convergent (destructive) and divergent (constructive) boundaries but not transform (conservative)

Question 7

How do volcanoes form?

Answer 7

Magma rises through cracks or weaknesses in the Earth’s crust
Pressure builds up inside the Earth
When this pressure is released, e.g. as a result of plate movement, magma explodes to the surface causing a volcanic eruption
The lava from the eruption cools to form new crust
Over time, after several eruptions, the rock builds up and a volcano forms

Question 8

What are the catagories of volcanoes?

Answer 8

active, extinct, dormant

Question 9

What is a active volcano?

Answer 9

Volcanoes that are erupting or have recently erupted

Question 10

What is a extinct volcano?

Answer 10

Extinct volcanoes that those that have not erupted for thousands of years

Question 11

What is a dormant volcano?

Answer 11

Volcanoes that have not erupted for over 20 years

Question 12

What are the types of volcanoes?

Answer 12

Fissure volcano, Shield volcano, dome volcano, ash-cinder volcano, composite volcano, caldera volcano

Question 13

What is a fissure volcano?

Answer 13

Fissure volcanoes are produced by eruptions that occur along elongated fissures versus at a central vent.

Question 14

What is a shield volcano?

Answer 14

broad volcanoes with gentle slopes and are shaped somewhat like a warrior’s shield lying flat on the Earth

Question 15

What is a dome volcano?

Answer 15

Domes form from the slow extrusion of highly-viscous silicic lava

Question 16

What is a ash cinder volcano?

Answer 16

the type of volcano that is formed by pyroclastic fragments like volcanic ashes, solidified lava pieces, volcanic clinkers, pumice and hot gases.

Question 17

What is a composite volcano?

Answer 17

a cone-shaped volcano built from several layers of lava, pumice, ash, and tephra

Question 18

What is a caldera volcano?

Answer 18

a large depression formed when a volcano erupts and collapses.

Question 19

What is a earthquake?

Answer 19

An earthquake is the shaking and vibration of the Earth’s crust
Earthquakes occur when tension is released from inside the crust

Question 20

What is the focus of a earthquake?

Answer 20

The point inside the crust where the pressure is released.

Question 21

What is a epicentre of a earthquake?

Answer 21

The point on the Earth’s surface above the focus

Question 22

Explain the basics of the energy released by a earthquake

Answer 22

Earthquake energy is released in seismic waves
These waves spread out from the focus

Question 23

Where are the waves felt the most and damage the most during a earthquake?

Answer 23

Epicentre

Question 24

What are the two types of waves release from earthquakes?

Answer 24

P and S waves

Question 25

What are the properties of P waves?

Answer 25

They can travel through solids and liquid and therefore can be felt on the opposite side of the earth

P-waves (P stands for primary) arrive at the detector first
They are longitudinal waves which mean the vibrations are along the same direction as the direction of travel

Question 26

What are the properties of S waves?

Answer 26

They can only travel through solids

S-waves (S stands for secondary) arrive at the detector of a seismometer second
They are transverse waves which mean the vibrations are at right angles to the direction of travel

Question 27

What are surface waves?

Answer 27

Surface waves are similar in nature to water waves and travel just under the Earth’s surface
They are generated when the source of the earthquake is close to the Earth’s surface

Question 28

What are the two basic kinds of surface waves?

Answer 28

Rayleigh waves, Love waves

Question 29

What are Rayleigh waves?

Answer 29

Travel as ripples similar to those on the surface of water

Question 30

What are love waves?

Answer 30

Cause horizontal shearing of the ground, they usually travel slightly faster than Rayleigh waves

Question 31

What is seismometer?

Answer 31

A seismometer detects the vibrations caused by an earthquake, it plots these vibrations on a seismograph

Question 32

What is the magnitude of a earthquake measured on?

Answer 32

The strength, or magnitude, of an earthquake is measured using the Richter scale which measures 0-10

Question 33

What is the amplitude of a seismic wave?

Answer 33

Theamplitudeof aseismic waveis the amount the ground moves as thewave passes by

Question 34

What is triangulation used for?

Answer 34

Used to locate the epicentre of an earthquake
Seismograms from three locations are used

Question 35

What are the steps of Triangulation?

Answer 35

Find the S-P time
Use a graph to find the distance from the epicentre
Using the scale on the map convert actual distance to map distance
Draw a circle on the map using the map distance as your radius and the seismograph location as the centre
Where the three circles cross is the location of the epicentre