Jefferys – Bullen Table and other earthquake knickknacks

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Discussion Overview

The discussion centers around the equations related to the Jefferys – Bullen Table, specifically focusing on calculating the distance or angle from a seismic station to the epicenter of an earthquake using the difference in travel times between S and P waves. Additionally, a mathematical approach to triangulating the epicenter's location using the intersection of circles on the Earth's surface is explored.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about the specific equation for determining the distance from a seismic station to the epicenter based on S and P wave travel time differences.
  • The same participant seeks a mathematical method for finding the intersection of three circles on the Earth's surface, given their radii and coordinates.
  • Several participants express difficulty in finding information online regarding these topics.
  • A participant provides a link to a resource that contains formulas related to travel time analysis at seismological stations.
  • Another participant acknowledges a spelling error in the name "Jeffery's" and thanks the contributor for the correction.

Areas of Agreement / Disagreement

Participants generally agree on the difficulty of finding the necessary information online, but there is no consensus on the specific equations or methods discussed.

Contextual Notes

The discussion does not resolve the mathematical steps required for triangulation or the specific equations used in the Jefferys – Bullen Table.

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I was wondering what is the equation that gives the values in a Jefferys – Bullen Table?
Specifically, what’s the equation for finding the distance (or angle) from a seismic station to the epicentre of an earthquake using the difference in travel times between S and P waves as recorded by the station?

Oh also, more of a math question, but I’ll use it for triangulating the location of the epicentre: How would one go about finding where 3 circles on the surface of the Earth intersect (if you know the radius of each circle and their coordinates on the Earth) mathematically?

My assignment is really to do this by estimating what the distance to the epicentre would be by looking up values on a Jefferys – Bullen Table and then triangulate them by drawing circles on one of those big globes that you can use chalk on. As you can imagine, it’s a very messy process. I already did it and figured out where the epicentre was; I just want to know how to do it mathematically.

Thanks!
 
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Anyone? I've tried googling to no avail...
 
Sorry Did the same, no luck too. I'm afraid internet is not the answer to all the questions.
 
http://www.igf.edu.pl/~pwiejacz/a/analysis2-wo-ojc.htm

I see formulas on this page

"Analysis of travel time residua at Polish seismological stations

1998-2003"

You just have to spell Jeffrey's name right
 
Last edited by a moderator:
LoL, thanks NileQueen. I guess I took the note wrote. It is indeed 'Jeffrey's'
 

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