Warm- Up Have your homework out for me to check and for several of you to share. Answer the following questions at the start of today’s notes. 1.Which hypothesis explains the occurrence of an Earthquake? 2.How does this hypothesis suggest and earthquake occurs? 3.What safety measures should you take in the event of a quake? TOC: 90. Measuring Quakes 91. Finding an Epicenter 92. EQ HW Keywords: • Body waves • P Wave • S Wave • Seismogram • Richter Scale • Moment Magnitude
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Warm- Up Have your homework out for me to check and for several of you to share. Answer the following questions at the start of today’s notes. 1.Which.
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Warm- UpHave your homework out for me
to check and for several of you to share.
Answer the following questions at the start of today’s notes.
1. Which hypothesis explains the occurrence of an Earthquake?
2. How does this hypothesis suggest and earthquake occurs?
3. What safety measures should you take in the event of a quake?
TOC:90. Measuring Quakes91. Finding an Epicenter92. EQ HWKeywords:• Body waves• P Wave• S Wave• Seismogram• Richter Scale• Moment Magnitude
Measuring Earthquakes
Seismographs measure the waves of energy distributed by the quake.
• Surface waves arrive last and are usually the most intense and destructive.
• Body waves travel through Earth and provide more insight.
Body Waves
P waves:• Compression waves• Alternately expand and
compress material they pass through
• Travel the fastest of all three waves
• Travels parallel to its movement
Body WavesS Waves• Transverse wave• Changes objects volume
temporarily• Travel slower than P waves• Travels at a right angle to
the direction of its movement
• TAKE A SMALL SHEET AND WORK WITH A PARTNER TO COMPLETE THE GRAPH
Locating an Earthquake
• Different speed of waves allows us to locate epicenter
• P Waves travel 1.7 times faster than S Waves
• The longer they travel, the greater the time lapse between them
Reading the Seismogram• Measure the time between
the P Wave ad the S Wave• The amount of seconds
corresponds to a distance based on the graph
• For example: a lag of 2 minutes indicate about a 700 mile distance from the epicenter (SMALL SHEET)
Locating an Earthquake• Station in Atlanta
reports seismic activity• Using the lag between
waves a radius for the location of the epicenter is created.
• How many points exist on the circle?
Locating an Earthquake
• Using another station in Louisiana provides another radius for the epicenter.
• How many points do the two radii have in common?
• What do these points represent?
Locating an Earthquake
• Using a third station pinpoints the Epicenter.
• How many points can all three circles have in common?
• All epicenters are located using 3 Seismic Stations.