How often do earthquakes occur?Once a yearOnce a monthOnce a weekOnce 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/

EarthquakesSeismology

Seismologist

Fault

Deformation

Elastic rebound

study of earthquakes

scientist who studies earthquakes and seismic wavesa break in the crust along which

plates shift and slip past each other rocks changing shape due

to stress from tectonic motion

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

P-waves S-waves L-wavesFull name

Where they

travel

Relative speed

Type of motion

Seismic Waves vibrations that are generated by the earthquake and travel through the Earth

pressure waves(primary)

shear waves(secondary)

Surface

through the entire earth

only through solid

on the earth’s surface

fastest slower slowest, but most damaging

back and forth

up and down

up & down, and side to side (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-mF1

MItalian Seismologists: http://www.nytimes.com/2012/10/23/world/euro

pe/italy-convicts-7-for-failure-to-warn-of-quake.html?_r=0

Earthquake Strength and IntensityWhat is the measure of the strength of an

earthquake called? Magnitude Richter scale

• Based on a factor of _____ for each level.

• A magnitude 3 is ____ times as strong as a

magnitude 2.

• A magnitude 4 is ____ times as strong as a

magnitude 3.

• A magnitude 4 is _____ times as strong as a

magnitude 2.

measures the strength of the ground motion 1

01010100

Historic EarthquakesChile 1960 May 22 19:11:14 UTC Magnitude 9.5The Largest Earthquake in the World

Mercalli ScaleMeasures Intensity – how much it is felt

by people and how much damage it causesNot 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

P Waves Arrive

S Waves Arrive

Identify the Richter Scale Magnitude of the earthquakeLas Vegas Seismic Station1. 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?