Applying Occams razor to determine Earths internal structure

What is inside ? How do you know what is inside?

How do you know what is inside? Think, Write, Pair, Share

Occam’s Razor - All other things being equal, the simplest solution is the best

Calvin and Hobbes by Bill Watterson Why might a model be important ?

Theoreticians Seismologist Hypothesis: the simplest solution to the question “What is beneath our feet”

Theoreticians Your task is to help test this hypothesis by creating a model of

Earth’s surface Center of the Earth Right Left o 180 Scale model of a

Seismologist Your task is to help test this hypothesis by analyzing a set of

REPLACE WITH YOUR OWN DATA Sample set shown

How does this anomaly in the data translate back to Earth?

Measure the geocentric angle from the epicenter to the anomaly in the data (108

Next, repeat this procedure to the bottom of the circle

Like a tree making a shadow, something is blocking the energy. Can we tell

Lay the cut out from Earth A on top of Earth B and trace

Next, rotate the cut out and continue to trace its edges

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Applying Occam’s razor to determine Earth’s internal structure V 3. 1 - Prepared by Michael Hubenthal http: //www. iris. edu/hq/resource/determining_internal_structure Adapted from Braile, 2000, Hubenthal, 2006 & DLESE Teaching Boxes, 2008

What is inside ? How do you know what is inside?

What is inside here?

How do you know what is inside? Think, Write, Pair, Share

Occam’s Razor - All other things being equal, the simplest solution is the best Based on your “evidence” what is beneath our feet?

Calvin and Hobbes by Bill Watterson Why might a model be important ?

Could this help us test our ideas?

Theoreticians Seismologist Hypothesis: the simplest solution to the question “What is beneath our feet” is a homogeneous Earth, or one comprised entirely of rock

Theoreticians Your task is to help test this hypothesis by creating a model of the Earth, using the known velocity of seismic waves in rock ~ 11 km/s to predict how long it should take seismic waves to reach various distances around Earth.

Earth’s surface Center of the Earth Right Left o 180 Scale model of a homogeneous Earth

140°

Seismologist Your task is to help test this hypothesis by analyzing a set of seismograms from a real earthquake to determine how long it takes for the seismic waves released from an earthquake to arrive at various points on Earth’s surface.

Seismologists Theoreticians

REPLACE WITH YOUR OWN DATA Sample set shown

How does this anomaly in the data translate back to Earth?

Measure the geocentric angle from the epicenter to the anomaly in the data (108 degrees for example). Use your ruler to connect the epicenter to the mark you just drew on Earth’s surface.

Next, repeat this procedure to the bottom of the circle

Like a tree making a shadow, something is blocking the energy. Can we tell what it is?

Cut out this shape from you model

Lay the cut out from Earth A on top of Earth B and trace along its edges (indicated with orange)

Next, rotate the cut out and continue to trace its edges