How often do earthquakes occur?
 Once a year
 Once a month
 Once a week
 Once a day
 http://www.seed.slb.com/flash/science/features/earth
/livingplanet/quake_map/en/index.htm?width=600&
height=500&popup=true&terms=epicenters
 http://earthquake.usgs.gov/
Seismology  study of earthquakes
Seismologist  scientist who studies earthquakes
and seismic waves
Fault  a break in the crust along which plates
shift and slip past each other
Deformation  rocks changing shape due to
stress from tectonic motion
Elastic rebound  stress builds up to the point
where the rock breaks and
snaps back
 Epicenter – the point on the Earth’s surface directly
above an Earthquake’s starting point
 Focus – the point inside the Earth where the
earthquake begins
Seismic Waves  vibrations that are generated by the
earthquake and travel through the Earth
Full name
P-waves
S-waves
pressure waves
(primary)
shear waves
(secondary)
L-waves
Surface
Where they through the
only through on the earth’s
entire earth
solid
surface
travel
Relative
slowest, but
fastest
slower
speed
most damaging
up & down,
Type of
back and forth up and down
and side to side
motion
(circle)
Surface wave
Seismic Wave Motion with Surface Effects
Seismic Wave Motion
Measuring Seismic Waves
 Seismograph – Instrument that record waves
 Seismogram – Printout of waves created by
seismograph
Seismographs
 Predicting Earthquakes (SCEC)
 http://www.youtube.com/watch?v=ixVVuN-mF1M
 Italian Seismologists:
 http://www.nytimes.com/2012/10/23/world/europe/italy-
convicts-7-for-failure-to-warn-of-quake.html?_r=0
What is the measure of the strength of an earthquake called?
Magnitude
Richter scale  measures the strength of the ground motion
•
10 for each level.
Based on a factor of _____
•
10 times as strong as a magnitude 2.
A magnitude 3 is ____
•
A magnitude 4 is ____
10 times as strong as a magnitude 3.
•
100 times as strong as a magnitude 2.
A magnitude 4 is _____
Historic Earthquakes
Chile
1960 May 22 19:11:14 UTC
Magnitude 9.5
The Largest Earthquake in the World
Mercalli Scale
 Measures Intensity – how much it is felt by people
and how much damage it causes
 Not as scientific because
 not based on seisomogram recordings but on peoples’
observations
 areas closer to epicenter will have higher intensity
 damage depends on quality of construction
S Waves
Arrive
P Waves
Arrive
Identify the Richter Scale Magnitude of the earthquake
Las Vegas Seismic Station
1.
What is the S-P lag time?
2.
What is the distance to the earthquake
epicenter?
3.
What is the S-wave amplitude?
4.
What is the magnitude using the nonogram?