Post on 05-Jan-2016
EARTHQUAKESYear 1 Science
EQ: WHAT 3 STRESSES LEAD TO EARTHQUAKES?
EARTHQUAKES
EARTHQUAKES ARE…Natural vibrations of crust that are caused by stress from plate tectonics
3 TYPES OF STRESSES
Compression:The squeezing of rock together until it folds or breaks
3 TYPES OF STRESSES
Tension:The pulling of the crust until materials thin and break
3 TYPES OF STRESSES
ShearPushing rocks into 2 opposite directions
EARTHQUAKE WAVES Vibrations of the ground during an earthquake are called seismic waves.
3 Types of Seismic Waves:
Primary Waves: waves that cause rock particles to move back and forth
Secondary Waves: cause rocks to move at right angles in relation to the wave
Surface Waves: waves that cause particles to move in two directions: up and down, side to side
EpicenterThe point on Earth’s surface directly above the focus
FocusThe point below ground where the earthquake originates
MEASURING EARTHQUAKES
SEISMOMETERS
Scientists use seismometers to measure ground movement caused by seismic waves
The strength of an earthquake = magnitude (a # given to an earthquake based on its strength)
RICHTER SCALE MEASUREMENTSScale Damage
0-4 Minor4-5 Light5-6 Moderate6-7 Strong7-8 Major8+ Catastrophic
NOTE REVIEW-Highlight the following headings:-3 Types of Stresses-3 Types of Seismic Waves-Measuring Earthquakes
-Circle the following terms in BLUE:-Earthquake, Tension, Compression, Shearing, P-Waves, S-Waves, Surface Waves, Epicenter, Focus, Seismometer, Magnitude
-Underline the definitions for the circled terms from above in GREEN