[Bass]

Both types of quakes produce the same amount of side-to-side and vertical waves surface waves. They are know as S-waves and P-waves. There is no rational explanation for the subjective experience. It just is.

There are two main types of seismic waves- body waves and surface waves.  JimBob is correct that the two types of body waves are (1) primary or P waves and (2) secondary or S waves (also known as shear waves).  P waves travel fastest and are often heard as a "snap" or "pop" whe the earthquake first starts.  Neither P waves or S waves cause much damage.
The damaging seismic waves are surface waves, and can be imagined as ripples in a pond- they are transmitted along the surface of the earth.  Two types here too: (1)Love waves and (2) Rayleigh waves.  Love waves cause side to side movements and Rayleigh waves cause up and down (rippling) movements.  Rayleigh waves are the most destructive.  Virtually all damage from earthquakes is from these surface waves, which travel slower than the body waves.

Shaking is intensified in buildings built on unconsolidated sediments (gravel, sand, mud) and is minimized in buildings built on bedrock.  We have occaisoinal quakes here- my house is on bedrock and barely moves, while my business partner's house is built on gravels/mud and gets shaken vigorously.

Karen, I agree- you never get used to them.

[JimBob]

So glad your back, Skippy Bass, I am overwhelmed. The mob is turning against me!

I didn't mention Rayleigh waves as they can be consider to be due to an interferance pattern produced by the interaction of P & S waves, like waves intersecting on a pond. They are not propagated as far from the epicenter as P & S waves. They are slower than body waves (P & S), roughly 70% of the velocity of S waves, and have been asserted to be visible during an earthquake in an open space like a parking lot where the cars move up and down with the waves.

Analysis of the witness accounts of Rayleigh waves I have seen suggest that the apparent motion may be due to distortion of the human sensory system during the earthquake. On TV shows I have seen, placing people on "shake tables" causes the room to appear to ripple to them. In any case, waves of the reported amplitude, wavelength, and velocity of the "visible waves" have never been recorded instrumentally.

[Make it Lady]

In todays Guardian it says for each whole number increase on the Richter scale represents a tremor 31 more times powerful than the last. My husband thought it would be 10 times more powerful. Could anyone put him right.

Also when I was in the quake in Japan the noise of things vibrating was the most frightening part but it did seem to interfere with my senses generally. I felt off balance as well.

[another_someone]

In todays Guardian it says for each whole number increase on the Richter scale represents a tremor 31 more times powerful than the last. My husband thought it would be 10 times more powerful. Could anyone put him right.

Your husband is right - no need to be put there.

[Make it Lady]

Are you sure? I can't cope with the gloating.

[another_someone]

OK  looking at wiki, it seems both sides are right.

http://en.wikipedia.org/wiki/Richter_magnitude_scale

The Richter magnitude scale, or more correctly local magnitude ML scale, assigns a single number to quantify the amount of seismic energy released by an earthquake. It is a base-10 logarithmic scale obtained by calculating the logarithm of the combined horizontal amplitude of the largest displacement from zero on a Wood-Anderson torsion seismometer output. The effective limit of measurement for local magnitude is about ML=6.8. The energy release of an earthquake scales with the 3/2 power of the shaking amplitude, and thus a difference in magnitude of 1.0 is equivalent to a factor of 31.6 in the energy released; a difference of magnitude of 2.0 is equivalent to a factor of 1000 in the energy released.
The Richter magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs (adjustments are included to compensate for the variation in the distance between the various seismographs and the epicenter of the earthquake). Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude; in terms of energy, each whole number increase corresponds to an increase of about 31.6 times the amount of energy released.

So a whole number increase is a factor of 10 increase in wave amplitude, but a factor of 31.6 increase in energy.

I should have read that first - sorry.

[JimBob]

Then don't tell him! Jees, I can't believe a woman can't be even have a little smidgen of deviousness.

[Make it Lady]

Husband still smug but not gloating anymore. It is nice when we are both right. Anyone got anything to add on this?

[Exodus]

Basically as is said in geography... a hazard only becomes a hazard when people locate themselves in its area... And whoever said that a 5 is not a big quake is wrong... If you look at the Richter scale graphically it is a base 10 logarithmic scale which means that each quake number is 10 times more powerful than the last... these means that a magnitude 5 is 100000 more powerful than a 1!

[Bored chemist]

"these means that a magnitude 5 is 100000 more powerful than a 1"
Er, no it doesn't. Each quake number has 10 times the amplitude of the one below not 10 time the power. I'm guessing the the velocity of the wave is prety much independdent of the released energy. That means that a change of 1 unit gives 10 times the apmlitude and so takes roughly 10 times as long. But it dissipates 31.6 times as much energy in that time so it has about 3.16 times more power. A magnitude 5 quake would be about 316 times the power but I don't know how that relates to how much damage is done.

[Exodus]

"these means that a magnitude 5 is 100000 more powerful than a 1"
Er, no it doesn't. Each quake number has 10 times the amplitude of the one below not 10 time the power. I'm guessing the the velocity of the wave is prety much independdent of the released energy. That means that a change of 1 unit gives 10 times the apmlitude and so takes roughly 10 times as long. But it dissipates 31.6 times as much energy in that time so it has about 3.16 times more power. A magnitude 5 quake would be about 316 times the power but I don't know how that relates to how much damage is done.

Indeed you are correct :-) gold star for you, detention for me. Walks away in shame.

[Make it Lady]

 I like your answer Bored C but I hope you don't gloat as much as hubby. Be humble in your glory.
Exodus, I just heard they have invented Sat Navs for zimmer frames so when senility takes over completely at least you can find your way home.

[Exodus]

I like your answer Bored C but I hope you don't gloat as much as hubby. Be humble in your glory.
Exodus, I just heard they have invented Sat Navs for zimmer frames so when senility takes over completely at least you can find your way home.

Its not senility today, its a hangover. lol

[JimBob]

I like your answer Bored C but I hope you don't gloat as much as hubby. Be humble in your glory.
Exodus, I just heard they have invented Sat Navs for zimmer frames so when senility takes over completely at least you can find your way home.

Why didn't you just say "walker" instead of zimmer frame? We Americans do not know what a bonnet is, a turtle or that both relate to a auto. That is all but I don't know.

Talk about the degradation of the English language.

[Make it Lady]

Which bit of a car is a turtle? I know you Americans drive slowly but turtles! Oh yes and on Docs behalf shouldn't it be an Auto. Anyway we are supposed to be talking about Earthquakes so lets take this outside.