4.14.17 Travel time, Shadow Zone, Intensity n Magnitude, IRIS Bill Nye?
figure 7.22
Region where seismic waves increase speed the most is:
what depth?
Because P waves travel faster what is here?
than S waves, Distance to focus can be determined by difference figure 7.23 Seismic waves inside the earth
in arrival time of P and S waves. reflected­ bouncing off layers
fig 7.12­ travel time graph
refracted­ bent (like light waves air/water)
absorbed­ S waves do not travel through the liquid outer core.
Some parts of the earth do not receive seismic waves after an earthquake....
How are earth quakes measured?
Intensity vs Magnitude
Mercalli scale is location specific. Any earthquake may result in people experiencing different intensities depending on distance away, ground conditions, for example.
Richter scale (of earthquake Magnitude) identifies how much energy was released by the earthquake. Logarithmic (exponential) scale. 1
4.14.17 Travel time, Shadow Zone, Intensity n Magnitude, IRIS Bill Nye?
figure 7.22
Region where seismic waves increase speed the most is:
what depth?
what is here?
Because P waves travel faster than S waves, we can use the difference in arrival times of seismic waves to determine the distance to a focus from a seismograph station. figures 7.11, 7.12, 7.21
fig 7.12 Travel time graph.
The path which seismic waves take is not straight...
fig 7.23 and handout
seismic waves get:
reflected­ bounce off different earth layers (dotted line in handout)
refracted­ bent/bend as they enter/leave layers of different densities/composition
absorbed­ as in S waves encountering a layer (such as the outer core) which has a liquid composition.
How are earthquakes measured?
Intensity vs Magnitude
Intensity is location specific. An earthquake can have several different intensities depending on the location where it is "sensed".
Richter Scale measures magnitude. Magnitude is a single measurement of how much energy was released by a particular earthquake. Logarithmic/exponential scale... IRIS website see Links section of teacher page.
Earth Models due for next class meeting...
check grading sheet BEFORE you think you are done...
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4.14.17 Travel time, Shadow Zone, Intensity n Magnitude, IRIS Bill Nye?
figure 7.22
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