Sunday, 17 December, 2017 @ 23:27:10

Author Topic: Scotland shaken  (Read 372 times)

0 Members and 1 Guest are viewing this topic.

Offline Maik

  • Administrator
  • Forum Deity
  • *****
  • Posts: 12130
Scotland shaken
« on: Saturday, 05 August, 2017 @ 12:07:46 »
Quote
Biggest earthquake in 30 years hits western Scottish Highlands
Magnitude 3.8 tremor in Moidart area is felt widely across west of Scotland

Scotland’s largest earthquake was a magnitude 5.2 event in Argyll in 1880, the BGS said.
https://www.theguardian.com/uk-news/2017/aug/04/earthquake-scottish-highlands-moidart

Offline disco69

  • Silver Medalist
  • ****
  • Posts: 90
Re: Scotland shaken
« Reply #1 on: Sunday, 06 August, 2017 @ 10:11:26 »
Quote
Biggest earthquake in 30 years hits western Scottish Highlands
Magnitude 3.8 tremor in Moidart area is felt widely across west of Scotland

Scotland’s largest earthquake was a magnitude 5.2 event in Argyll in 1880, the BGS said.

To my knowledge the Richter scale was invented 1935, 55 years after the event, so where does 5.2 come from ?

Offline Maik

  • Administrator
  • Forum Deity
  • *****
  • Posts: 12130
Re: Scotland shaken
« Reply #2 on: Sunday, 06 August, 2017 @ 14:28:13 »
To my knowledge the Richter scale was invented 1935, 55 years after the event, so where does 5.2 come from ?

Hmmmm... well, yes, the Richter scale wasn't invented until 1935. Before that 'quakes were measured but using a different scale:

Quote
The first simple classification of earthquake intensity was devised by Domenico Pignataro in the 1780s. However, the first recognisable intensity scale in the modern sense of the word was drawn up by P.N.G. Egen in 1828; it was ahead of its time. The first widely adopted intensity scale, the Rossi–Forel scale, was introduced in the late 19th century. Since then numerous intensity scales have been developed and are used in different parts of the world.
https://en.wikipedia.org/wiki/Seismic_scale


These days the Richter scale (ML suffix) has been superseded, emsc-csem use body-wave magnitude (Mb):

Quote
The magnitude is a number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph. Several scales have been defined, but the most commonly used are (1) local magnitude (ML), commonly referred to as "Richter magnitude", (2) surface-wave magnitude (Ms), (3) body-wave magnitude (Mb), and (4) moment magnitude (Mw). Scales 1-3 have limited range and applicability and do not satisfactorily measure the size of the largest earthquakes. The moment magnitude (Mw) scale, based on the concept of seismic moment, is uniformly applicable to all sizes of earthquakes but is more difficult to compute than the other types. All magnitude scales should yield approximately the same value for any given earthquake.
https://earthquake.usgs.gov/learn/glossary/?term=magnitude

Think it's the last sentence that's what we're looking for  :dunno: