tectonics L4 earthquake measurements

Question 1

Earthquakes — Mercalli Scale

Answer 1

measure intensity
1 (hardly noticed) - 12 (catastrophic)
uses shaking & damage reports to describe EQ impacts

Question 2

Earthquakes — Moment Magnitude Scales (MMS)

Answer 2

measure magnitude
logarithmic — up 1 = 30x
use seismometers & plot them as a seismogram

Question 3

types of WAVES

Answer 3

P-Waves:
- longitudinal
- pass through solids & liquids
- travel from fault quickly (8km/s)
- caused by compression

S-Waves:
- transverse
- pass through solids
- move more slowly (4 km/s)
- vibrate at right angles to direction of travel

L-Waves:
- travel along surface of earth from epicentre
- causes side to side motion

R-Waves:
- travel within the crust causing a vertical motion
- orbital

Question 4

Earthquake Prediction

Answer 4

• small shocks and tremors
• animal behaviour
• seismic gaps
• USGS measure earthquakes around the world
• modern seismic monitoring and advanced communications allow for warnings up to a minute before

Question 5

tsunami prediction

Answer 5

• can be caused by any sub-marine earthquakes
• warning systems in pacific and indian ocean with buoys monitoring the movement of the sea and sea floor
• computer modelling used to predict arrival times
• NOAA monitor tsunami buoys in the pacific