Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with...
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Transcript of Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with...
![Page 1: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/1.jpg)
Triangulation
Finding earthquake’s epicenter using seismograms!
In Class Activity (working with shoulder partner is A – OK!)
![Page 2: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/2.jpg)
![Page 3: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/3.jpg)
• Focus – the place deep in the crust where the earthquake begins (source of primary and secondary waves)
![Page 4: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/4.jpg)
• Epicentre – the surface location directly above the focus (source of surface waves)
![Page 5: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/5.jpg)
Let’s say station #1 knows the earthquake happened 200 kms away.
![Page 6: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/6.jpg)
But 200 kms in what direction?
![Page 7: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/7.jpg)
If a second station reports it as 75 kms away, they can draw a circle and see where it
intercepts the first circle.
![Page 8: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/8.jpg)
But that still doesn’t pinpoint the location – it could have happened at either spot where the
two circles touch.
![Page 9: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/9.jpg)
But a third station removes all doubt as to where it happened.
![Page 10: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/10.jpg)
Three seismographs are needed to pin- point the source of an earthquake.
![Page 11: Triangulation Finding earthquake’s epicenter using seismograms! In Class Activity (working with shoulder partner is A – OK!)](https://reader033.fdocuments.in/reader033/viewer/2022052701/56649cf05503460f949beb79/html5/thumbnails/11.jpg)
• Nomograph
Finding Magnitude
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In class activity
• We’re going to find an epicentre of an earthquake in San Francisco
• Lesson 12 http://maccallum.wikispaces.com• Paper and Pencil activity• Let’s do 1st one together! Walk through it.• You and shoulder partner can quietly work on
the last 2 seismograms• What is the average magnitude of this San
Francisco earthquake? • Please raise hand when finished.• If I saw your work, you can try the links at the
bottom of wikispace (Virtual Earthquake)