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