Seismicity

Question 1

Seismicity

Answer 1

Shaking of the earth.

Question 2

Focus

Answer 2

The point within the crust where the pressure releases

Question 3

Fault

Answer 3

Areas where the crust is being forced to move in the opposite directions.

Question 4

Seismic waves

Answer 4

The waves of energy that travel away from the focus after the stress along a fault line is released.

Question 5

Epicentre

Answer 5

The area on the surface directly above the focus.

Question 6

Seismograph

Answer 6

A device that records P and S waves.

Question 7

Primary waves

Answer 7

Fastest, compressional. Fastest through solids and liquids.

Question 8

Secondary waves

Answer 8

Travel at half the speed of P-Waves, move with a perpendicular motion, cannot move through liquids but do more damage that P-waves

Question 9

Surface waves

Answer 9

Travel slowest and near to the ground. Slowest but most destructive.

Question 10

Love waves

Answer 10

Surface waves that make the ground move up and down

Question 11

Raleigh waves

Answer 11

Surface, cause a complex heaving or rolling motion

Question 12

Magnitude

Answer 12

Amount of energy released by an event, measured on the Richter scale

Question 13

Richter scale

Answer 13

Logarithmic scale, each units represent a 10 fold increase in strength, and a 30 fold increase in energy release

Question 14

Modified Mercalli Scale

Answer 14

Measures the intensity of the event and its impact. It’s a 12 point scale.

Question 15

Aftershocks

Answer 15

Earthquakes that follow on from the main event and may last for a few months afterwards, generated by the earth settling back after the disruption of the first displacement.
Some can be significant events in their own right.

Question 16

Soil liquefaction

Answer 16

When shaken violently, soils with a high water content lose their mechanical strength and start to behave like a fluid.

Question 17

Tsunami

Answer 17

Giant sea waves generated by shallow-focus underwater earthquakes, volcanic eruptions, underwater debris slides and large landslides into the sea.

Question 18

Earthquake

Answer 18

When the stress that builds up within the up rocks is suddenly released, causing parts of the surface to experience an intense shaking motion that lasts between a few seconds and a few minutes.