Quick Science question: Earthquakes

[VanessaofBC]

What are the differences between a Richter magnitude scale and the Mercalli intensity scale.

Wiki references do not count. Explain it to me.

Thanks.

 

[badbadboy]

From what I recall from Geology courses is the Mercalli scale 1 - 12 is totally based upon "observation" while the Richter Scale on a Base Ten of 1 - 10 is a measured response by a Seismograph. If you have seen those TV shots of all the squiggly lines they are measurements on a 0 -1, 1 - 10, 10 - 100 etc.

Basically at the end of the day a 12 on the Mercalli and a 10 on the Richter are both the same = Total Destruction.

Enjoy your day on this beautiful sunny day Vanessa and leave these dark thoughts for rainy December days

 

[VanessaofBC]

From what I recall from Geology courses is the Mercalli scale 1 - 12 is totally based upon "observation" while the Richter Scale on a Base Ten of 1 - 10 is a measured response by a Seismograph. If you have seen those TV shots of all the squiggly lines they are measurements on a 0 -1, 1 - 10, 10 - 100 etc.

Basically at the end of the day a 12 on the Mercalli and a 10 on the Richter are both the same = Total Destruction.

Enjoy your day on this beautiful sunny day Vanessa and leave these dark thoughts for rainy December days

ound: Thanks. That was faster than I thought!

 

[Dman1980]

Richter = That's measurable and corresponds to the energy released in a logarithmic scale.
Mercalli-Cancani-Sieberg = It refers to how much impact the earthquake had in terms of destruction. It goes from I (not felt) to XII (total destruction).

They don't necessarily correlate, but they usually do.

I hope this helps!

D

 

[vancity_cowboy]

the richter scale requires a seismograph, whereas the mercalli-c-s scale can be reported by the effects people felt at the place they were at the time it happened

a quake reported as 7.9 off the coast of alaska (richter scale right at the epicentre) might only feel like a 2.3 (richter) or less in vancouver

a comparison can be found at http://www.diffen.com/difference/Mercalli_Scale_vs_Richter_Scale

 

[bcneil]

What are the differences between a Richter magnitude scale and the Mercalli intensity scale.

Wiki references do not count. Explain it to me.

Thanks.

Actually wiki is the perfect place for such a question. This is a grade 6 science question. Not exactly ring theory....

 

[VanessaofBC]

Actually wiki is the perfect place for such a question. This is a grade 6 science question. Not exactly ring theory....

Yeah, I looked at wiki...if a 6th grader can explain this to me, I would be impressed. Maybe my Ontario education system failed me

There are several scales which have historically been described as the "Richter scale," especially the local magnitude M_L and the surface wave M_s scale. In addition, the body wave magnitude, m_b, and the moment magnitude, M_w, abbreviated MMS, have been widely used for decades, and a couple of new techniques to measure magnitude are in the development stage.
All magnitude scales have been designed to give numerically similar results. This goal has been achieved well for M_L, M_s, and M_w.[7][8] The m_b scale gives somewhat different values than the other scales. The reason for so many different ways to measure the same thing is that at different distances, for different hypocentral depths, and for different earthquake sizes, the amplitudes of different types of elastic waves must be measured.
M_L is the scale used for the majority of earthquakes reported (tens of thousands) by local and regional seismological observatories. For large earthquakes worldwide, the moment magnitude scale is most common, although M_s is also reported frequently.
The seismic moment, M_o, is proportional to the area of the rupture times the average slip that took place in the earthquake, thus it measures the physical size of the event. M_w is derived from it empirically as a quantity without units, just a number designed to conform to the M_s scale.[9] A spectral analysis is required to obtain M_o, whereas the other magnitudes are derived from a simple measurement of the amplitude of a specifically defined wave.
All scales, except M_w, saturate for large earthquakes, meaning they are based on the amplitudes of waves which have a wavelength shorter than the rupture length of the earthquakes. These short waves (high frequency waves) are too short a yardstick to measure the extent of the event. The resulting effective upper limit of measurement for M_L is about 7[4] and about 8.5[4] for M_s.[10]
New techniques to avoid the saturation problem and to measure magnitudes rapidly for very large earthquakes are being developed. One of these is based on the long period P-wave,[11] the other is based on a recently discovered channel wave.[12]
The energy release of an earthquake,[13] which closely correlates to its destructive power, scales with the 3⁄2 power of the shaking amplitude. Thus, a difference in magnitude of 1.0 is equivalent to a factor of 31.6 (=({10^{1.0****)^{(3/2)**) in the energy released; a difference in magnitude of 2.0 is equivalent to a factor of 1000 (=({10^{2.0****)^{(3/2)** ) in the energy released.[14] The elastic energy radiated is best derived from an integration of the radiated spectrum, but one can base an estimate on m_b because most energy is carried by the high frequency waves.

Here's the link, my friend! http://en.wikipedia.org/wiki/Richter_magnitude_scale#Details

I did find this on wiki which was helpful, so I should thank you for that.

The Richter and MMS scales measure the energy released by an earthquake; another scale, the Mercalli intensity scale, classifies earthquakes by their effects, from detectable by instruments but not noticeable to catastrophic. The energy and effects are not necessarily strongly correlated; a shallow earthquake in a populated area with soil of certain types can be far more intense than a much more energetic deep earthquake in an isolated area.

 

[peter putter]

Verbose, but readable....

.

Readable perhaps if you have a geoscience, physics or engineering degree, otherwise its blah, blah, blah...

 

[peter putter]

Opps, double post.. my bad..

 

[MrBrown]

Sometimes I am just amazed (read: pleasantly surprised) by the level of intelligence, sophisticated humor, life experience and education I find on this board from both the ladies and pooners.

 

[VanessaofBC]

Why the sudden interest in earthquakes miss vanessa? Just those unexplained movements of the bed. Lol

Thinking about the 2004 Indonesian Earthquake/Tsunami if you all must know.