shaking & trembling that results from movement of rock beneath Earth’s surface
TLC-Make a quake
Focus -area beneath Earth’s surface where rock under stress breaks Epicenter -point on surface directly above focus
vibrations that travel thru Earth carrying energy released during earthquake
carry energy from earthquake away from focus Earth’s interior across surface
types of seismic waves P waves S waves surface waves
P rimary waves
1 st to arrive
move thru. solids & liquids
compress & expand like accordion
S econdary waves
2nd to arrive
vibrate from side to side & up & down
cannot move thru. liquids
move slower than P & S waves
produce the most severe ground movements
3 types of seismic waves
3 ways of measuring earthquakes Mercalli scale Richter scale moment magnitude scale rates earthquakes according to level of damage rated using seismographs estimates total energy released by earthquake rates earthquakes of all sizes (near & far) good for small, nearby earthquakes describes how earthquakes affect people, bldg. & land
The Mercalli scale was developed to rate earthquakes according to the amount of damage at a given place.
Mercalli Scale Earthquake Intensity Earthquake Effects I-III People notice vibrations like those from a passing truck. Unstable objects disturbed. IV-VI Dishes and windows rattle. Books knocked off shelves. Slight damage. People run outdoors. VII-IX Moderate to heavy damage. Buildings jolted off foundations or destroyed. X-XII Great destruction. Cracks appear in ground and landslides occur. Waves seen on ground surface.
# geologists assign to earthquake based on earthquake’s size
how much energy released
instrument that records & measures ground movements of seismic waves
use seismic waves
measure difference between arrival times of P & S waves using data from 3 seismographs
draw 3 circles from different seismographs
point where they intersect= epicenter
A Vocabulary Review Activity
One student stands with their back to this presentation.
Another student gives the student clues to the vocabulary word onscreen as a clock keeps time.
The student tries to guess the word before the buzzer.