Chapter 2 Section 3 Objectives F231 Explain how a seismograph works F232 Describe how Geologists monitor faults F233 Explain how seismograph data is used The Seismograph Seismic waves cause the seismographs drum to vibrate but the suspended weight with the pen attached move ID: 559104
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Slide1
Monitoring Earthquakes
Chapter 2 Section 3Slide2
Objectives
F.2.3.1. Explain how a seismograph works.
F.2.3.2. Describe how Geologists monitor faults.
F.2.3.3.
Explain how
seismograph data is used.Slide3
The Seismograph
Seismic waves cause the seismographs drum to vibrate but the suspended weight with the pen attached moves very little. Therefore the pen remains still and records the vibrations on the drum.Slide4
The Seismograph
When the ground shakes, it shakes the base of the seismograph but the pen stays steady because the heavy weight will tend to stay still because of its resistance to motion. Slide5
Reading A Seismogram
Which type of wave is fastest? Second Fastest? Slowest?Slide6
Seismogram
Which wave arrives first?
Primary
Why?
Because it is the fastest wave.Slide7
Seismogram
Which wave arrives second?
Secondary
Why?
They are slower than primary waves.Slide8
Seismogram
Which waves arrive last?
Surface Waves.
Why?
They are the slowest.
What is significant about Surface Waves?Slide9
They Are The Most Destructive!Slide10
Instruments To Monitor Faults
To monitor faults, scientists have developed instruments to measure changes in elevation, tilting of the land surface, and ground movements along fault boundaries.Slide11
Instruments To Monitor Faults
These instruments are called:
Tilt Meters
Creep Meters
Laser Ranging Devices
Global Positioning SatellitesSlide12
Tilt MetersSlide13
Tiltmeter
A tiltmeter measure changes in the angle of the ground from horizontal.Slide14
TiltmeterSlide15
Creepmeter
A
creepmeter
uses a wire stretched across a fault. On one side the wire is anchored to the ground and on the other side it is attached to a weight that can slide along a scale.Slide16
CreepmeterSlide17
Installation Of A CreepmeterSlide18
Laser Ranging DevicesSlide19
Laser Ranging Devices
Laser Ranging Devices use a beam of light to measure movements in Earth’s Plates.Slide20
Laser Ranging Devices
From The Earth
To The MoonSlide21
Global Positioning System
GPS can be used to measure changes in the position of receivers located on opposite sides of a fault. They can be accurate to 1 mm in the horizontal and 5 mm in the vertical.Slide22
GPSSlide23
GPS Triangulation
Triangulation looks at at least ____ reference points to determine precise locations of the receivers.
3Slide24
Seismographic Data
Seismographs and fault monitoring devices are used for:
Mapping Faults and detecting changes.
Develop a method of predicting earthquakes.Slide25
Mapping Faults
Faults are often hidden because they are deep underground. When seismic waves encounter faults they are reflected to reveal the faults location. Slide26
Monitoring Changes On Faults
Geologists need to know about changes along a fault to ESTIMATE earthquake risk. Faults that move easily tend to be low risk, faults that get stuck can be very high risk. Slide27
Predicting Earthquakes
Can scientists predict earthquakes?
Absolutely not!
As of today, Geologist can only estimate risk for certain areas. Slide28
Assessment Of Objectives
F.2.3.1. This objective is fair game for the quiz
. How does a seismograph record the ground shaking of an earthquake? Slide29
F.2.3.1.Slide30
F.2.3.2
What are some ways scientists are able to monitor faults?
Tiltmeters
Creepmeters
Laser Ranging Devices
Global Positioning SystemsSlide31
F.2.3.3.
What do scientists use seismic data for?
Mapping faults
Monitoring changes along fault lines.
Predicting earthquakes.
This objective is fair game for the quiz.Slide32
Predicting Earthquakes
Can Geologists predict the time and or location of earthquakes? Can you predict for me right now the time and location of the next automobile accident in Waukegan.
Not a chance.Slide33
Assessing Risk
Based on research and observation, could we determine which roadways and intersections are at a higher risk for accidents?
Absolutely
This is about the best earthquake prediction we can get to at this time.