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Flashcards in Earthquakes Deck (18):
0

Seismic wave

The energy released by an earthquake

1

P wave

Primary wave. Fastest waves. Start from focus. Move through solids and liquids.

2

S waves

Secondary wave. Second fastest. Moves through solids only. Start from focus.

3

Surface waves.

Slowest wave. Most destructive. Start from epicenter. Travel olmly at surface.

4

Focus

The underground origin of the earthquake. P and S waves start here.

5

Epicenter

The spot on the surface of the ground where the shaking is worst. Above focus. Surface waves start here.

6

Plate boundaries

Most earthquakes occur along plate boundaries.

7

Identify the fault, focus and the epicenter in a picture

Fault = the break in the rock

Focus = the first slippage of the rock

Epicenter = point on the surface above the focus

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8

Fault

Any break in the crust

9

Amplitude

The height of a seismic wave.  

Tells geologists how powerful an earthquake is.

10

S-P Lag Time

The difference from the start of the P wave to the start of the S wave.

Can be used to tell how far away an earthquake is.

11

Which seismic station was closer to the earthquake, Tokyo or Sydne?

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Tokyo, because the lag time is smaller and the amplitude is larger.

12

Which city was closest to the earthquake?

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Montreal, because the lag time is the smallest.

13

Liquefaction

The mixing of soil and groundwater duing an earthquake. Can lead to buildings sinking into the soil.

14

Ground dispalcement

movment of the crust along a fault

15

Tsunami

Large wave caused by uplifiting crust under the ocean during some earthquakes.

16

What is the lag time of this seismogram?

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About 14 seconds.  P wave arrives at 10 seconds and S wave arrives at 24 seconds.

17

What is the amplitutde for this seismogram?

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About 18 mm.