Talk:Seismic wave

From Wikipedia, the free encyclopedia

	Portal This article is part of WikiProject Earthquakes, a project to systematically present information on earthquakes, seismology, plate tectonics, and related subjects. If you would like to participate, you can choose to edit the article attached to this page (see Wikipedia:Contributing FAQ for more information), or join by visiting the project page.
???	This article has not yet received a rating on the quality scale.
???	This article has not yet received a rating on the importance scale for WikiProject Earthquakes.
	If you have rated this article please consider adding assessment comments. Help with this template

Surface waves do NOT cause most damage in earthquakes. High horizontal accelerations responsible for most damage are associated with shear waves (S-waves). Some geologists think that, because the surface wave traces are largest on seismograms from distance earthquakes, that surface waves cause the damage. Although the displacement of surface waves is usually higher than that of shear waves at teleseismic distances, horizontal accelerations are highest in the near field when the shear waves arrive, and these high horizontal accelerations do the damage.

This error has propagated through generations of physical geology textbooks.

Some seismologists are looking into a new kind of surface wave called a basin-generated wave, but strong motion seismograms usually reveal that the damaging motions are inconsistent with classical Love or Rayleigh waves, the surface waves well recorded hundred to thousands of kilometers from large earthquakes.

Shear wave amplification and resonance in the soft sediments of deep basins is a well know and understood phenomenon.

Hmm... ^{[citation needed]}? - Hamsterlopithecus (talk) 07:24, 7 February 2008 (UTC)

[edit] wave

[edit] Length of Article

In general, I find this article too long and comprehensive, with few outside references. Would it be good for a highschool project? I have started to divide some of these things into 1-page focused articles. These are then good for links in other articles. It's a question as to the 'social purpose' of the wiki ??? --Zeizmic 16:44, 13 December 2005 (UTC)

In my opinion, 'outside references' - I presume by that you mean citations from scientific journals - are not terribly important, or even necessary, if the information presented is accurate (because it comes from direct, first-hand work experience). That is how experts are created, as much as study. I've noticed that some eminent experts - scientists - have been contributing their first-hand knowledge, in various fields. Excellent! Wiki needs 'em. I am never too concerned if an obvious expert in a field does not give references, but just says blah blah blah, this is what it's about. Good for him, or her. That person can condense a lot of information into relatively compact form, and spare other people the long and probably tedious study of that subject. And there are always other people come along and say, this is not quite correct, so it gets adjusted. Or added to. So usually it ends up quite accurate.

Who reads the journals anyway, but the experts? Not very many people! And: citation is a game in itself. There has been strong criticism of the policy of using the number of times a paper is cited as a measure of its quality, for example. Some scientists have said: wrong! (Just to cite the problem with citations.) They are not only used, today, but also abused. "Ha, I've been cited 112 times! Even so: that paper may not be terribly exciting or interesting or valuable or useful. Yet, citations have become the default rating system. Foolishly so, in the opinion of some scientists, who I happen to agree with.

Fact is: you can probably find supporting information/references on your own, using Google, if you want it. Type in any term: you can obtain a whole lot of information outside Wiki, about anything. Enough to boggle the mind, and growing rapidly. Wiki should not be considered 'the universe of information'. It's not important that it be 'the authoritative source', as long as the info is well-written and accurate.

In the case of this article...I authored better than half of it, as it stands. That's because I worked in seismology for a number of years. I saw gaps in the article as it was. So I added my knowledge. During my work in seismology I located many earthquakes, using a program I wrote, from scratch. My locations typically agreed very well with the official USGS epicenters, even though I was using data from merely three seismograph stations, and my own equations, which I derived, carefully, from published, well-accepted travel-time charts.

So, that's my reference: personal work experience. Years of it.

Maybe the article is 'too long and comprehensive' in your opinion, but I don't see the harm in being comprehensive, nor any harm in presenting information of a more esoteric nature. Someone else may think: wow, those waves *bounce* inside the earth? I didn't realize that.

Why is such information important? I think it's important because it may give that person a clue, how we happen to know so much about the inner planet. It's because the shock waves from earthquakes do bounce and refract! Thus, the inner Earth is subject to mathematical analysis, and can be effectively *observed*.

This is an encyclopedia, not a dictionary, after all.  :-) You may not be too interested in some of the information given - (yawn, where did that video game control get to?) - but someone else may find it quite interesting. That is the nature of the human beast. I realize I'm sounding a bit 'Hemmingway' here, but...one man's milk is another man's poison. Law of human nature! In fact: a lot more could be said about the subject of P and S than I said.

Like: what if you reverse them, and make them S and P? But I didn't want to wear out my keyboard.

The 'social purpose' of any encyclopedia is - of course - to inform, and enlighten, and hopefully do it well, in a way that it's enjoyable to read, and maybe even entertaining. Why? So people will want to read, at a time when they are - in great numbers - forgotting how to. When 'R U 2?' came along, I was shocked, frankly! For a surprising number of people, that's standard English now! Shudder. The chinks speak better English than that! Sorry. Chinese. We're all becoming 'PC' these days too, tragically. As well as only partly literate. The lucky ones. I think Wikipedia admirably succeeds in its goal, which I personally believe is: turning back the tide on the illiterates, the semi-literates and the people what don't read so good. It's becoming a serious source of information. Impressive. Just from a lot of contributions, by a myriad unpaid people. Imagine that: a communist system. See: communism. (And I offer also a prayer: may the cyber-vandals who have done naughty in Wiki, and you know who you are, all die, most painfully, preferably by...being sanded, with an electric power sander...slowly...down to nothing. Beat that for a curse on the evil ones. To quote George Bush. Who I note: can't read too well. See? Even politics thrown into this reply!)

Those who can't read, or who prefer *short* paragraphs, of ideally one or two sentences...should not mess with encyclopedias, in my opinion. No. Because: encyclopedias can require some patience. (Also an old-fashioned virtue, very uncommon these days, I've noticed.)

I would say: don't be too eager to slice things up, too much. Much of what is there has *already* been sliced - rather tragically (sniff) - out of Seismology. Just to shake things up, I guess. (A seismic joke.) At least the information was not moved to mythology. Notice: just to annoy you: a too long, comprehensive reply.  :-) Stellar-TO 00:19, 21 April 2006 (UTC)

Question about the sentence in the opening paragraph: "Seismic waves are also continually excited by the pounding of ocean waves and the wind." I thought it would be seismic waves that initiate waves (tsunamis) not the other way around. Is this supposed to be there? If so, maybe it should be explained later in the article. I don't want to delete it unless it should be deleted.

This is correct - commonly referred to as microseismicity. For example, every time a wave breaks on the shore, the impact sets up waves which you can see on seismograms. It is clearly visible in a comparison of seismic records from stations on islands, as compared to those in the middle of the continents. And don't get me started on stations near motorways... These seismic waves are not large, but they are detectable. J chaloner 22:47, 14 February 2007 (UTC)