Earthquake Waves: Finding Epicenter Using Seismograph Data (Con't)

OPENING QUESTIONS:

None Today.

Please work with your team to finish finding the epicenter of the quake we were working on last time. All of the graphs are still on today's plan if you need them.

When you are done, please scroll down on THIS page to work on how to find the magnitude of that event.

LEARNING TARGET:

1) I will work with my team to analyze & summarize last Friday's Reading during today's class.

2) I will practice calculating the epicenter of an earthquake using seismograph data during today's class

3) I will work with my team to calculate the magnitude of the earthquake we are currently analyzing

WORDS O' THE DAY:

  • Primary (p) waves - Travel through all types of material and arrive first.
  • Secondary (s) waves - Only travel through solid rock (not liquids of any sort) and arrive later
  • Surface waves - Only travel along the surface of the earth-- they arrive LAST but are most destructive
  • focus - The location of an earthquake inside the Earth
  • epicenter - The point on the Earth's Surface directly above an earthquake

WORK O' THE DAY:

GRAPHS
 

Here's a *varsity* level assignment. The following images are from seismographic data taken at three different places around the world.

Some aspects of those graphs make your life a *WHOLE* lot easier. Others, well, not so much.

Your job is to use whatever tools you have at your disposal to address our activity question:

Where did this earthquake occur?

MAGNITUDE CALCULATION:

Background:

There is CLEARLY an inverse relationship between the magnitude of earthquakes and their frequency:

Now let's work to calculate the magnitude of that earthquake event using a fairly rough approach. The following to graphics are 'nomograms' that are created using richter scale data.

The problem with Richter data is that it is HUGELY based on Southern California data, which, not at all coincidentally was where Richter lived.

There is no one-size-fits-all nomogram because the geological characteristics of each part of the Earth's crust are different.

However, since we are NOT seismologists, we'll give a whirl with the Richter Nomogram:

Take a swing at use on or both of the nomograms to calculate the magnitude of the current EQ we're analyzing. Feel free to reach out to the wizard for guidance!

If you're feeling rather *mathy* you can always do this:

Where:

  • ML = Local magnitude

  • = Maximum amplitude of seismic waves (in millimeters)
  • = Epicentral distance (in kilometers)

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