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Epicenters and hypocenters[edit]

According to Merriam-Webster Online at [1], an epicenter is: 1:the part of the earth's surface directly above the focus of an earthquake.

According to Merriam-Webster Online at [2], a hypocenter is: 1:the focus of an earthquake; 2:the point on the earth's surface directly below the center of a nuclear bomb explosion.

However, I have seen many places which refer to the epicenter for an above ground explosion or some other news-worthy event. I have revised the text of this article to not mention above ground explosions, but feel free to revert if you disagree.--Astronaut 20:25, 10 Mar 2005 (UTC)

As I understand it, the term epicentre is used to refer to air-burst nuclear explosions in an analagous way to earthquakes i.e. hypocentre = where the bomb goes off, epicentre = point on ground vertically beneath hypocentre. I agree it needn't be in here though - needless complication IMO. —Preceding unsigned comment added by (talk) 14:52, 19 September 2005

No, Merriam-Webster is correct. It's the other way round: epicentre (or focus) = where the bomb goes off, hypocentre = point on ground vertically beneath epicentre. Astronaut 23:23, 10 August 2007 (UTC)

If "The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus" we need a (straight) line to follow in order to project the hypocenter onto the Earth's surface. Such line needs to be defined in the article. I suppose it is the line that passes through the Earth's geometrical center and the hypocenter, but I am not sure. (EPLeite 16:04, 1 December 2009 (UTC))

I think the meaning of "above" is quite obvious and doesn't require further explanation. Astronaut (talk) 17:22, 1 December 2009 (UTC)


Does not S-wave stand for secondary-wave and not shear-wave?

The P/S nomenclature may have originated as 'primary' and 'secondary', but if you were to ask a seismologist what they stood for he would say 'comPression' and 'Shear', simply because that is far more helpful in describing what they are.

Removed for clarification[edit]

Removed this recent addition:

epicentral distance-it is the angle subtended at the center of the earth between the point of recording and the is normally represented by degrees and represented by Δ.
Δ1 degree=110 kilometeres
and Δ cannot be greater than 180 degree

as it needs serious rewriting if it is to be included. Vsmith 13:19, 19 August 2006 (UTC)

"Usage Panel"[edit]

The third paragraph as it presently stands expounds at length on the various opinions of "the Usage Panel". What is this panel and why are its opinions treated with such reverence as to include them in an encyclopaedia article? 17:19, 6 March 2007 (UTC)

No idea; but whoever added this apparently ripped it off somewhere - it was removed as a copyvio. Astronaut 23:26, 10 August 2007 (UTC)

Merge proposal: Epicentral distance[edit]

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section.

The result was merge into DESTINATION PAGE. Astronaut (talk) 21:06, 17 May 2008 (UTC)

I'm sure some of the information from Epicentral distance could be merged into this article. I'll do it in a few days unless there is some objection. Astronaut (talk) 09:04, 13 May 2008 (UTC)

Agreed --APShinobi My Contribs 15:37, 13 May 2008 (UTC)

The above discussion is closed. Please do not modify it. Subsequent comments should be made in a new section.

epicenter and focus[edit]

epicenter is the point situated above the the focus it is the point on the surface of the earth from where the earthquake initiates the massive destruction takes place at the epicenter —Preceding unsigned comment added by (talk) 04:02, 26 August 2008 (UTC)

Unit of "epicentral distance"?[edit]

Several references in Surface wave magnitude prints º as the unit for epicentral distance. This is neither a measure of distance nor one of time. What is the dimension of epicentral distance? This is particularly troublesome because without proper understanding of all related units and their reference values, definitions cited in these sources, even the original Richter formula are incoherent. Sillyvalley (talk) 07:06, 14 September 2008 (UTC)

I think ° (note degree symbol, not º) is a perfectly valid measurement of epicentral distance - measuring the number of degrees between the measuring station and the epicentre. For example, an epicentral distance of 5° indicates the epicentre is approximately 556 km from the measuring station (calculated as follows: Earth circumference/360*5). Astronaut (talk) 15:55, 15 September 2008 (UTC)
Thanks. This makes sense and needs to be added to the page - may need to find some citation, though. BTW, the Chinese site actually prints º - making things even more confusing. (The other paper is a scanned Image.) Sillyvalley (talk) 17:24, 15 September 2008 (UTC)

image queue[edit]

Link to image showing global earthquake epicenters, 1963–1998 (Copyied from earthquake) — Preceding unsigned comment added by Tideflat (talkcontribs) 17:29, 3 June 2012 (UTC)

There is no need to show the actual image here when you can provide an explanetory link. Astronaut (talk) 17:32, 4 June 2012 (UTC)
What do you mean by "image queue" and why bring this image here? I don't understand what you are trying to show. Astronaut (talk) 17:32, 4 June 2012 (UTC)

First use in 1874?[edit]

I reverted this edit. Firstly, I doubt this is true. I can find no evidence for the existance of Gods Walk Among Us by Henry Gull, and the reference "London public library" is worryingly imprecise. Unless (or anyone else) can come up with compelling evidence of this, I think it should stay removed. Astronaut (talk) 11:26, 16 September 2013 (UTC)

The term was coined by Robert Mallet e.g.[3], although I haven't managed to find an exact date for that. Mikenorton (talk) 19:44, 16 September 2013 (UTC)

Misuse of the word[edit]

There is a widespread error in common usage, to the effect that "epicenter" is treated as synonymous with "great center" or "ultimate center".
But like the similar misuse of "quantum leap", I do not know what to do about it. Perhaps if one finds it in a published article, one might redirect the reader to this excellent definition. DaveyHume (talk) 16:00, 26 March 2015 (UTC)

There is a section in the article. Myrvin (talk) 16:19, 26 March 2015 (UTC)
Why does the artilce say in Wikipedia's voice that using epicenter to mean center is "misuse"? The OED, Webster, American Heritage, etc. all say it can mean "focal point" or "center". It is verifiable that Garner's says you shouldn't use it that way, and Safire quotes a geophysicist who calls those who use it that way "scientific illiterates".

Wikipedia does not call it "misuse" to use work in to mean things that don't agree with Work (physics). Just the same with moment, force, momentum, and so on. Any Wikipedia article that scolds people for using normal langauge in the normal way, denigrating it as "popular usage", needs to be corrected. We are not the language police, and even if we were, all the dictionaries say it's legal.

If anything, we ought to scold the geologists for their halfassed Latinized Greek. --Dennis Bratland (talk) 00:16, 22 July 2017 (UTC)