Talk:Seismic magnitude scales

Test links
Test of M links to appropriate sections in Seismic magnitude scales.



Magnitudes in the CFTI5MED catalogue
Particularly for historical earthquakes, the Italian CFTI5MED catalogue typically uses what they call for magnitude, but that has nothing to do with "energy magnitude". It actually means "magnitude equivalent", which is derived from macroseismic data. To quote

"To parameterise all earthquakes listed in CFTI5Med we used the Boxer computer code v. 3.321. Boxer uses intensity data to assess the location, moment-magnitude, physical dimensions and orientation of the source of large historical earthquakes. The macroseismic epicentre is calculated as lying in the middle of the spatial distribution of all sites that suffered the largest intensities. The magnitude, referred to as “equivalent magnitude” or Me to clarify that is an inferred - non measured - estimate, is obtained based on the average epicentral distance (i.e., the radius) reached by each intensity level. As the magnitude is calibrated using 20th century earthquakes for which both the intensity pattern and the moment-magnitude Mw are known with confidence, the Me obtained using Boxer corresponds to the Mw. It is well known that the epicentral intensity I0 decreases for an increasing hypocentral depth, and vice-versa. This implies that Me may be substantially larger or smaller than the magnitude one could obtain from empirical laws using only I0, depending on hypocentral depth."

So, do we need another magnitude type? here is obviously related to other macroseismic scales, but doesn't seem to be exactly the same as any of the ones already covered in the article. I was looking through the maintenance category for M?, or Earthquakes with unspecified magnitudes as it's now known and came across some that use CFTI5MED as a source, hence the question. Mikenorton (talk) 21:16, 28 April 2020 (UTC)

Broken ref/missing source
The harvnb ref to Gutenberg 1945b is broken. The list of sources has Gutenberg 1945a and c but b is missing: odd. Chiswick Chap (talk) 17:24, 17 December 2020 (UTC)

Last sentence
As a novice who just generally wanted to know what scale I was looking at when magnitudes are referenced in publications, I found the very last sentence in this article to be particularly informative and wished it appeared a little earlier.

‘An ordinary (non-italic, non-bold) capital "M" without subscript is often used to refer to magnitude generically, where an exact value or the specific scale used is not important.’ 203.211.105.39 (talk) 07:24, 22 December 2022 (UTC)