Quakes by the numbers

Delmar Fairchild, Barron, WI — Mon, 12 May 2008 23:56:30 GMT

You are right in saying a 7.9 in a wasteland would not make an impact. The Strength of a quake or other natural disaster can only be measured on the amount of people killed or damage to man made structures. If a size 10 quake ever happened and there were no people in the area, it is a non issue. People will not bat an eye, except possibly for the quake watchers.
We still need to study the Earth and her wonders, or we will never learn to live with her. We are in the correct time period with the correct resources to do some fabulous discoveries about the Earth. We shouldn't let that slip by.
Those images of Myanmar you suggested are scary. Can't imagine how people can survive such devastation when their own government doesn't care about them.

Quakes by the numbers

Jaycubed — Mon, 12 May 2008 23:58:01 GMT

Our testing oriented Math education at work.

Most Americans don't have a clue what a Logarithm is or what a Logarithmic Scale looks like.

Quakes by the numbers

Harry — Tue, 13 May 2008 00:50:42 GMT

Thanks for the scientific distinction and the new terminology. It's difficult sometimes for the novice to understand the magnitude of their own misunderstandings

Quakes by the numbers

Jack Inslee, Denver, Colorado — Tue, 13 May 2008 02:35:58 GMT

Laast year I visited Concepcion, Chile and was told that it was near the center of the strongest earthquake ever recorded - 9.7 on the Richter scale in 1960. As the article points out, sheer scale numbers do not tell the whole story. The devastation in Concepcion was not as great as in some other lower rated 'quakes.

Quakes by the numbers

Delmar Fairchild, Barron, WI — Tue, 13 May 2008 04:05:55 GMT

Jaycubed: Most people that I know that ever used a Logarithmic scale are math teachers and a scientist type friend that works with large numbers and Alan Boyle. I guess I don't get out much. Most other people only G-A-S about balancing their check books.

Being educated in our system today or even when I graduated in '65 only gives you a base to work with. If you are not in the position to work upon that base continually, you will have forgotten more than most people in the world would have ever learned.
Then there is always Wikipedia for those of us that have forgotten and want to bone up on the basics we learned in the past but have not used.
I think I would be correct in saying, when I fell off a horse back when I could still get on one, a size 10 (very rare) Earthquake would shake the ground ten billion (10 to the 9th power)times greater than what the ground shook when my butt hit it. Never-the-less, I can still feel it every time I get up to walk. So that contusion on my butt at one/ten billionth of a size 10 quake had a greater impact on me than any other Earthquake I have ever felt.
I was in the Army in 1966 in Anchorage and have seen first hand the damage a 9.2 had done. I also felt smaller tremors during my stay there. They were very interesting and the area was something to take pictures of and write home about for a dumb hick kid from the north woods of Wisconsin. But let me tell you, not once did I have to mention the Richter Magnitude scale based on the log-10. People just weren't interested in it.

Quakes by the numbers

EricGF, Eustis, FL — Tue, 13 May 2008 05:55:51 GMT

Well, Delmar, if you make a decision, and your wife isn't there to hear it, is it still wrong?

And Jaycubed, as a retired Aerospace forensic Engineer, and a musician, most people have seen a logarithmic scale, on the neck of a guitar, but don't know what they are looking at.

Quakes by the numbers

RPM, Clark, NJ — Tue, 13 May 2008 09:34:13 GMT

Good morning,
To my knowledge common log uses base 10 therefore your statement that,
"A magnitude-7 quake releases 31.6 times more energy than a magnitude-6 quake, and 1,000 times as much as a magnitude-5."
is confusing I have learned that differece of 1 is ten times, so 7 is ten times larger than 6 and hundred times larger than 5. Thanks.

Quakes by the numbers

Andy La Plata, MD — Tue, 13 May 2008 12:46:04 GMT

You know what's scary? The Richter scale is open-ended.
(Although, I vaguely remember hearing/seeing/reading that a realistic upper limit is 12.0 for a naturally occurring earthquake, i.e. one not induced by a cosmic collision or some such event.) I bet a 12.0 would get your attention no matter where on Earth it occurred.

Quakes by the numbers

Rob Roy Edmond Ok — Tue, 13 May 2008 13:16:47 GMT

Isn't it amazing that those of us reading this already know what your talking about. Those that don't know won't read this anyway.

Quakes by the numbers

Sci inform — Tue, 13 May 2008 15:02:38 GMT

Seems like every 41 to 43 years there's a major earthquake in this area. In 1933, 9000 people died. In 1976, over 200000 died. In 2008 another one. Why aren't people well informed to not live there? Not many know about the frequency in this area, or this info is not given to the people living there.

What's going on under the earth in this area with such frequency?

Quakes by the numbers

Alan Boyle — Tue, 13 May 2008 16:54:27 GMT

Dear RPM: Yes, there's a lot of confusion over that logarithmic scale. Even The Associated Press Stylebook is confused, because they say "every increase of one number ... means that the quake's magnitude is 10 times as great." Which doesn't make sense.

Here's the authoritative word from the USGS:

"Since these magnitude scales are all logarithmic, a whole number increase in magnitude represents a 10-fold jump in measured amplitude, for example, a magnitude 4.0 has 10 times the measured amplitude of a magnitude 3.0. The total energy released from an earthquake increases even more rapidly with magnitude. A whole number increase in magnitude represents a jump in released energy of about 31.6 times. A magnitude increase of two whole numbers represents an increase in released energy of 1,000 times."

http://hvo.wr.usgs.gov/volcanowatch/2008/08_02_21.html

I stuck with energy rather than amplitude because it worked a little better for me in the explanation. But this is a good occasion to define another term.

Again quoting USGS, amplitude refers to the size of the seismic wave generated ... that is, the size of a wiggle recorded on a seismogram. That has to be translated into the figures for the energy release. While the step increase from one number to the next number up is the power of 10 for amplitude (10¹), the step increase for the energy is 10^1.5, or 31.6. For two steps, the amplitude increase is 100 (10²), but the energy increase is 1,000 (10³, or 31.6 times 31.6).

Quakes by the numbers

Jaycubed — Tue, 13 May 2008 17:48:50 GMT

Jaycubed: Most people that I know that ever used a Logarithmic scale are math teachers and a scientist type friend that works with large numbers and Alan Boyle.
Delmar Fairchild"

"And Jaycubed, as a retired Aerospace forensic Engineer, and a musician, most people have seen a logarithmic scale, on the neck of a guitar, but don't know what they are looking at.
EricGF"

In his autobiography, Richard Feynman attributes much of his later success in Physics to time spent as a child memorizing Log tables (as well as other such tables, remember this was more than half a century before scientific calculators existed). By understanding what the numbers in certain progressions/curves were he was able to observe patterns in data that others would miss.

For such a technique to work, only approximations are necessary, rather than the false "extreme accuracy" of computers/calculators. A slide rule, inscribed with numerous scales, is able to quickly and with high (but not extreme) accuracy do complicated math problems.

As Eric points out, a string instrument is a grouping of logarithmic scales of frequency (each string to itself). But our eyes and ears also see and hear logarithmically. (ie. sensitivity to light & sound amplitude are logarithmic. The deciBel scale is logarithmic. The Magnitude scale for stars is logarithmic.)

It is not that examples are uncommon, it is that such patterns are unrecognized by the vast majority.

Perhaps the best thing for math students would be to prohibit electronic scientific calculators from class and instead go back to teaching math with a slide rule; where one can actually see scales, curves & relationships. The process the student uses is transparent as compared to the occult practice of entering numbers into a computer/calculator and reading the answer numbers out.

ps. Eric, most people have not "seen a logarithmic scale, on the neck of a guitar". All they see is the neck & strings. If you don't know what "it" is, you can't actually see "it". You can only "see" what you understand. And, sadly, most people are happy to be half-blind to the world.

pps. I was recently calculating on paper (for fun & personal knowledge) how long it would take an object accelerating at 1G to reach lightspeed. A simple logarithmic progression.

Quakes by the numbers

Delmar Fairchild, Barron, WI — Tue, 13 May 2008 22:23:18 GMT

EricGF: I don't quite understand what you are trying to say--- but to play along;
My wife says that I have selective hearing, but according to space aficionados, there is no sound in space due to it's vacuum (no air, therefore no wave frequencies to hit our ear drums), so if she says something and I don't hear it, I can tell her to just chalk it up to the vacuum of my "space" in a logarithmic way. The more she talks or louder she talks, the higher the selective hearing gets. And I am sure there is a "10" on that scale.

Quakes by the numbers

Scott Pogue, Birmingham AL — Tue, 13 May 2008 23:59:14 GMT

Could the fill/drain cycle at the Three Gorges Dam have contributed to the recent 7.9 magnitude quake there? The reservoir is just south of the major fault lines in the region and the 150' drain/fill fluctuation would add/remove close to 70 trillion pounds of pressure on the underlying geology. I would be like sitting on the "up" end of a see-saw when your three hundred pound playground buddy jumps off of the "down" end. Ouch!

Quakes by the numbers

marilyn morehead — Wed, 14 May 2008 01:09:55 GMT

I like the last comment the best. amplitude increase is hundred times but energy increase is 1,000. that is starting to make sense now.

Quakes by the numbers

Mervin Mullins Delta Junction Alaska — Wed, 14 May 2008 02:18:29 GMT

You missed a major point about large earthquakes--the epicenter is not the only concern. The 2002 7.9 Denali Earthquake involved over 100 miles of fault line. The greatest damage was at the end of the fault AWAY from the epicenter! (In fact, the epicenter was not even on the Denali Fault--it was on a small intersecting fault.) The epicenter is simply where the slippage starts--and the only place where there is a distinct signal that can be easily triangulated. The damage zone for a 7.9 is a long oval--not a circle.

Quakes by the numbers

P Bush — Fri, 16 May 2008 12:20:00 GMT

Delmar...who is "her"?

FYI, the Earth is not my Mother.

Quakes by the numbers

Judy Sealy Barbados — Sat, 17 May 2008 18:23:13 GMT

My prayers go out to all those wo have been affected by this disaster. I can imagine the torture , horror, torment and everything else those persons are going through. It is time that real attention is paid to what has been happening around the world.Only God can really know when a natural disaster will occur.Therefore we need to get back to God . We need to realize that biblical perdictions are being fulfilled.Let us accept that we are approaching the end of this world, repent and seek God before it is too late.Let us be realistic because it is customary to return to our old ways after the storm subsides. Wake up people.Just remember that someone's world ends every day.Only God can change the situation.Let us all pray .

Quakes by the numbers

Porsa, Na , Italy — Mon, 19 May 2008 21:25:43 GMT

The earthquake is a natural phenomenon. It is important to consider the ground effects induced by the earthquakes such as primary effects( faults) and secondary effects (liquefactions, landslides, fractures, hydrological changes etc). A new macroseismic scale is named :Environmental Seismic Intensity scale - ESI 2007, is composed by:

a) the Definition of intensity degrees on the basis of Earthquake Environmental Effects, i.e. the scale itself, which follows the same basic structure of the widely used twelve degrees macroseismic scales ;you can find it on
http://www.apat.gov.it/site/en-GB/Projects/
INQUA_Scale/Environmental
_Seismic_Intensity_Scale_-_ESI_2007/