Exploring Earth’s structure using Occam’s Razor
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Transcript of Exploring Earth’s structure using Occam’s Razor
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Exploring Earth’s structure using Occam’s Razor
Prepared byMichael Hubenthal, IRIS Consortium
Adapted from Braile, 2000 & DLESE Teaching Boxes, 2008
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How do you know what is inside?
What is inside ?
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What is inside here?
Think, Write, Pair, Share
How do you know what is inside?
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How do you know?
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Occam’s Razor - All other things being equal, the simplest solution is the best
Based on your “evidence” what is beneath our feet?
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Cal
vin
and
Hob
bes
by B
ill W
atte
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Why
are
mod
el im
port
ant i
n sc
ienc
e?
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Could this help us test our model?
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Theoreticians
Seismologist
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Theoreticians
Seismologist
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Earth’s surface
Center of the Earth
Scale model of a homogeneous Earth
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140°
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Seismologists
Theoreticians
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Creating a travel-time plot
•Work in teams of ~ 2•Each pair calculates 3 travel times
•Each team makes 1 travel time plot, 0-180 degrees•Discuss results
Use velocity=11 km/sec, distance scale 320 km/cm
103040507080100115130150
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Earthquake Wave First Arrivals
Distance From Epicenter (Deg)
Time (Min)
What is the cause of model and observations mismatch?
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Shadow zone
Something changes beyond ~110 deg.
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Combine results from multiple earthquakes
Assumptions?
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?
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What has your data established so far?
Have we found any layers?
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1st: 1 deg - .5 min2nd: 16 deg - 3.5 min
First Arrivals
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http://rev.seis.sc.edu/
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Earth’s Interior Structure - Seismic Travel Times in a Constant Velocity Sphere
(L. Braile , December, 2000)
:http// . . . /~web ics purdue edu braile
R = 6371 km
Δ
/ 2
S / 2
Raypath
(chord of length S)
R = 6371 km
Earth’s
Surface
Source
Receiver
Copyright 2000. L. Braile. Permission granted for reproduction for non-commercial uses.
http://rev.seis.sc.edu/ > DLESE Teaching Boxes!
Updated Version