Talk:Modified Mercalli intensity scale

Removed part of the article
"The terms Mercalli intensity scale or Mercalli scale should not be used unless one really means the original ten-degree scale of 1902." Is what I removed. The sentence has no bearing and cannot be cited, as it seems it is more a matter of someones opinion then anything else. The fact is that the Modified Mercalli scale is still used commonly today in seismology and yes, it has been modified, making it the UPDATED version of the scale. Meaning there should be no reason to not use the name "Mercalli scale" just because it isn't the same as it once was. I mean, should we not call an iMac an iMac anymore because it's been modified a few generations? No.

Second sentence unclear
The second sentence under the subhead on the article page needs to be reworked; it doesn't make sense as it stand. Looks like perhaps something was copied incorrectly or incompletely.

If this isn't the right place to put this comment, please let me know. I'm a noob.

Cr8aAvatar (talk) 17:08, 13 May 2008 (UTC)

Richter Scale
I was just looking through a book and found some rough Richter equivalents to these. If anyone thinks this might be appropriate, tell me and I will supply them (although I cannot edit tables myself, I don't have the knowledge.)Squid 17:56, 8 June 2007 (UTC)
 * You can find this in the Romanian article: ro:Scara Mercalli (and also the table syntax). Could you check if it corresponds with your sources? --Alex:Dan 11:15, 19 June 2007 (UTC)
 * They are grouped differently but roughly follow the same pattern. I'll get back to you soon... Squid 18:13, 10 October 2007 (UTC) —Preceding unsigned comment added by Squidnchips (talk • contribs)

i like thnigs

Intensity is a measure of earthquake effects; magnitude is a measure of the energy output. The two cannot be directly compared.

A car analogy: Intensity is like 0-60 time, while magnitude is engine displacement. A bigger engine usually means faster times, but this is affected by car weight, transmission, wheel traction, road quality, etc.

Similarly, a higher magnitude earthquake creates higher intensities, but it is affected by various factors-- your distance from the earthquake, soil condition, rupture directivity, type of buildings, etc. 68.32.210.166 02:44, 9 October 2007 (UTC)trickpony Do catastrophic earthquakes cause haboobs? After all, the greatest earthquakes cause massive mudslides and throw rocks, people, cars I assume, etc. into the air, do they also cause massive, towering clouds of sand in desert regions? 24.184.234.24 (talk) 02:46, 2 June 2009 (UTC)LeucineZipper —Preceding unsigned comment added by 24.184.234.24 (talk) 02:43, 2 June 2009 (UTC)

Source
The scale chart is from Cambridge Encyclopedia. I own a 2006 version of this encyclopedia.-- Vintei  Talk  18:19, 8 July 2008 (UTC)

this didnt help —Preceding unsigned comment added by 96.229.174.98 (talk) 01:03, 9 December 2008 (UTC)

This scale doesn't measure intensity
Actually it doesn't measure anything. It's not even a scale really. It's just a classification scheme where earthquakes are classified according to their perceived effects by people. Two equally intense earthquakes may be classified on different categories (so called "degrees" here) depending on whether there were people and/or human constructions on the areas the earthquakes took place. This is just a subjective classification scheme. —Preceding unsigned comment added by 200.86.177.42 (talk) 09:35, 11 December 2009 (UTC)

Calligraph scale?
I've marked this term (bottom of article) 'citation needed' because I couldn't Google any references to this phrase, or to its assertion. The 'Calligraph scale' also doesn't appear on the Seismic scale page. (And don't know a better template.) I'm guessing the editor meant the old-fashioned pen-ink Kinemetrics seismometer?? Twang (talk) 22:50, 13 January 2010 (UTC)
 * I removed all mention of the Calligraph scale because I couldn't find anything on Google, other than mirrors of Wikipedia of this very article. The idea about the old-fashioned pen-ink Kinemetrics seismometer sounds inviting, but the article needs some kind of citation to even mention the Calligraph scale. Obankston (talk) 09:06, 13 March 2010 (UTC)

Level XIII - Cataclysmic
From a textbook I had at school a while back, the Mercalli scale had a level that was even higher than XII-Catastrophic. It was XIII-Cataclysmic, when the damage is so extensive that maps of the affected areas have to be redrawn from scratch. Has this been abandoned, or was there just no real consensus about this extra level? --  Blanchardb - Me•MyEars•MyMouth - timed 02:41, 22 January 2010 (UTC)

The Intensity of the Modified Mercalli Scale always stopped at XII - anything higher as you claim is someone's idea of or lack of comprehending what "Total Destruction" means. After every earthquake regardless of intensity the maps are checked and only after survey work is an accurate idea provided of the effect. — Preceding unsigned comment added by 88.107.82.79 (talk) 16:22, 7 August 2015 (UTC)

Wait, do we really know what "Total Destruction" means? Or is it just me. --Iol_Iizzy 14:52, 17 February 2021 (UTC)

Estimation
Can anyone please add how the intensity values are estimated for unpopulated areas as done by the PAGER system? --Thogo (Talk) 08:59, 12 February 2010 (UTC)

Richter Scale versus Mercalli Scale
Anyone knows why insurance companies use the Modified Mercalli Intensity Scale instead of the Richter Magnitude Scale in classifying earthquakes? Thanks.
 * I don't know for sure, but its probably simply that insurance companies are most interested in how much damage is done (which is what the MMI scale measures), rather than how much the earth moved. Especially as extremely high-magnitude earthquakes can do relatively little damage (if they hit unpopulated and/or well-constructed areas), and weak earthquakes can cause massive damage (if tehy hit somewhere with lots of people in weak buildings). Wardog (talk) 16:26, 9 May 2012 (UTC)


 * No - I think you are both confused about what the Richter Magnitude Scale is. Firstly, it was intended to give some idea of the total size of the earthquake, but it is out of date and has generally been replaced by the Moment Magnitude scale, whose units are energy (Joules). Secondly, the size of the earthquake tells you nothing about the level of damage to individual buildings (which is what the MMI scale is intended for), although it may give some idea of the geographical range of the damage. The peak intensity experienced in the Christchurch EQ was similar to the peak intensity experienced in Japan due to the Great Eastern EQ (Sendai), but the size of the earthquake (the energy released) was magnitudes larger, and the area over which the ground motion was felt was also much much larger. Since the epicenter was off the coast, there were no buildings that directly experienced the near-fault ground motion. --Muchado (talk) 08:38, 25 March 2015 (UTC)

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How can there be a Mercalli reading for the "Sendai" quake when no one was at the epicenter to feel it? Or, are they saying this was the damage/feeling in Sendai (~ 70 miles from the epicenter)? This isn't clear. —Preceding unsigned comment added by 71.203.126.185 (talk) 18:46, 12 March 2011 (UTC)


 * From the article: "The effects of any one earthquake can vary greatly from place to place, so there may be many Mercalli intensity values measured for the same earthquake. These values can be best displayed using a contoured map. Each earthquake, on the other hand, has only one magnitude."
 * If I were an insurance agent, I too would be more concerned with how much the ground was shaking in the claimant's neighborhood (what intensity scales like Mercalli indicate) than how much energy was released at the earthquake's focus - miles away and miles underground (what Magnitude scales indicate). If they used the Richter Scale, everyone in Japan would be filing an insurance claim for every wall or driveway crack they had.
 * "are they saying this was the damage/feeling in Sendai (~ 70 miles from the epicenter)?"
 * I assume so, because that is all that intensity scales can indicate, how bad the ground was shaking on the surface at a specific location, based on how it felt to people there and damage done to structures there. — Preceding unsigned comment added by The myoclonic jerk (talk • contribs) 08:27, 14 March 2011 (UTC)

People in Tokio felt the earthquake and it was felt further south too. The MM scale where the earthquake was felt. Seismographs can and do record earthquakes thousands of kilometers away BUT crucially you would not feel an earthquake that happened half way round the world. — Preceding unsigned comment added by 88.107.82.79 (talk) 16:25, 7 August 2015 (UTC)

Instrumental?
This is a very odd use of the word. I'm assuming it means that the quake is only noted by measuring instruments. Perhaps this should be explained? 24.21.175.70 (talk) 07:16, 11 January 2012 (UTC)

Why explain what "Instrumental" means when talking about scientific equipment. However for those who do not understand it means that only scientific instruments recorded the activity - you can build a simple seismograph and that is an instrument. — Preceding unsigned comment added by 88.107.82.79 (talk) 16:27, 7 August 2015 (UTC)

Classes of buildings and structures
According to the Cambridge Encyclopedia, 1990, Owl Publishing House, the Mercalli scale (year 1956 iteration) includes four classes of buildings, A, B, C and D:

Class A buildings have well-designed construction, plaster and masonry, reinforced horizontally with steel rebar concrete. Buildings of this class are designed to resist external forces.

Class B buildings have well-designed construction, plaster and masonry. They are reinforced with steel rebar concrete but are not designed to resist external forces.

Class C buildings have mediocre-quality construction, plaster and masonry. The major weak points of these buildings are located at the corners of walls. These buildings are not reinforced with steel rebar concrete and are not designed to resist external forces.

Class D buildings have poor-quality construction with inferior material and little plaster. These buildings cannot resist external forces.

It further specifies that:

By intensity VI, Class D buildings start to develop visible cracks and fissures.

By intensity VII, Class D buildings are considerably damaged, some start to collapse. Class C buildings start to develop visible cracks and fissures.

By intensity VIII, Class C buildings are considerably damaged or are partially collapsed. Class B buildings suffer minor damages. Class A buildings remain intact.

By intensity IX, all Class D buildings are completely collapsed. Class C buildings are severely damaged or are entirely collapsed. Class B buildings suffer considerable damage. Foundations of all buildings are damaged.

--173.178.17.48 (talk) 01:14, 21 March 2012 (UTC)

Addition of casualties to table
I've reverted the addition of casualties to the table of effects, because I cannot find a source that gives any such information. If anyone has a source for this, then they could be put back, suitably cited. Mikenorton (talk) 19:03, 18 December 2012 (UTC)

You are quite correct - there is NO correlation between intensity and casualties, nor is there any correlation between magnitude and casualties. — Preceding unsigned comment added by 88.107.82.79 (talk) 16:29, 7 August 2015 (UTC)

Historical analysis section
I'm not sure why we have a table of earthquakes with casualties, magnitudes and intensities. It's not a historical analysis, or anything really, except a rather random set of earthquakes in no particular order. If no-one objects, I'll remove this section. Mikenorton (talk) 20:54, 18 December 2014 (UTC)


 * That looks like a good move; the article has several (more relevant) tables already. Dawnseeker2000   00:07, 19 December 2014 (UTC)


 * I finally removed it. It didn't add anything to the article. Next is that giant (and hideous) table in Richter magnitude scale. Dawnseeker2000   20:23, 25 April 2015 (UTC)

Magnitude to intensity table
The magnitude/intensity comparison table in the Mercalli intensity scale section makes it appear as though magnitude and intensity are directly comparable, when in reality, the magnitude (number) necessary for a certain intensity is frequently lower than the intensity (number) of the shaking it produces. An earthquake definitely doesn't need to have a magnitude of 7.0+ to produce intensity VIII shaking. Dustin ( talk ) 20:58, 30 April 2015 (UTC)

I corrected the table with values from the USGS website, however we have to consider that these are approximate values, typical of shallow earthquakes. — Preceding unsigned comment added by 80.117.11.5 (talk) 21:29, 9 October 2016 (UTC)

Intensities past X
The strongest intensity I've ever seen listed for an earthquake is X. Are XI and XII even used? Have they ever been used? Alex of Canada (talk) 09:30, 31 December 2017 (UTC)


 * Here is the NOAA list of all earthquakes in their database with intensities of XI or XII. Mikenorton (talk) 11:54, 31 December 2017 (UTC)

Proposal to rename
I am proposing to rename this page "Modified Mercalli intensity scale" (adding "Modified" to the existing title).

The seismic intensity scale introduced by Giuseppe Mercalli in 1902 has evolved greatly in the succesive modifications by Cancani (1904), Sieberg (1912, 1923), Wood and Neumann (1931; this version explicitly named the "Modified Mercalli Intensity Scale of 1931"), and Stover and Coffman (1993) (for details see Mercalli intensity scale), and though still bearing a familial resemblance to its great-great-grandfather the modern version of this scale should be distinguished by retaining the "Modified".

It is particularly pertinent to note a comment from a senior seismologist a few years ago:

The 1902 version is not still in use, and has not been for sometime; its only notability is as a somewhat distant progenitor of the current scale, which is (in its several variations) the Modified Mercalli intensity scale. The article title should follow the form that is notable. &diams; J. Johnson (JJ) (talk) 23:32, 3 January 2019 (UTC)


 * Support - Makes sense. Mikenorton (talk) 11:35, 5 January 2019 (UTC)
 * Done. &diams; J. Johnson (JJ) (talk) 23:10, 6 January 2019 (UTC)
 * I'm curious as to whether the Modified Mercalli intensity scale is more commonly known under that name or as "Mercalli intensity scale". Wikipedia's naming conventions is to go with the more commonly used term. Volcanoguy 21:51, 25 March 2019 (UTC)
 * True, but WP:COMMONNAME also says "Ambiguous or inaccurate names for the article subject, as determined in reliable sources, are often avoided even though they may be more frequently used by reliable sources.", which is I think relevant here. Mikenorton (talk) 22:01, 25 March 2019 (UTC)


 * VG: Are you suggesting that 1) the demonstrably incorrect form is more common? And that 2) we should go with that? &diams; J. Johnson (JJ) (talk) 23:42, 25 March 2019 (UTC)
 * J. Johnson I don't know if it's more commonly used that's why I asked. Mikenorton several scales have been modified throughout history yet they still go by their original name. Volcanoguy 21:32, 28 March 2019 (UTC)


 * I see that as a poorly specified question. E.g.: do you mean as used by authoritative, scientific sources? Or as used on local TV? On the WorldWideWeb?
 * I did several quick searches for '"modified mercalli intensity"' and '-modified "mercalli intensity"' on Google and Google Scholar. On Google I got "about" 99,000 and 88,000 hits; near parity. (And indicative of large scale confusion, which is hardly surprising as lots of people don't understand the difference between intensity and magnitude.) On Google Scholar — which is largely restricted to authoritative sources — there were just under 8,000 hits, and a mere 528, resp. A big difference, with the latter likely due to (per Musson and Cecić, quoted above) carelessness.
 * As to the difference being minor: not really. The original "Mercalli" intensity scale — and that one did have two versions — is sufficiently different that it would be unclear to use, and therefore imprecise, even erroneous, in result. One might argue that since the older scale is no longer used there would be no confusion in which one is meant. But in a sense it still is in use: historical records. Smaller differences are seen in the MMI versions of 1931, 1956, and 1993, but as they all use the same name they might be considered "the same scale". But not the same as the "original", or even the "original.2", version of Mercalli's scale.
 * Does that satisfy your itch of curiosity?
 * Yes, someday I would like to expand this article, but that is such a low priority it isn't even on my "to-do someday" list. &diams; J. Johnson (JJ) (talk) 23:09, 28 March 2019 (UTC)