Answer:
Richter first applied his magnitude scale to shallow-focus earthquakes recorded within 600 km of the epicentre in the southern California region. Later, additional empirical tables were set up, whereby observations made at distant stations and on seismographs other than the standard type could be used. Empirical tables were extended to cover earthquakes of all significant focal depths and to enable independent magnitude estimates to be made from body- and surface-wave observations. A current form of the Richter scale is shown in the table.
Richter scale of earthquake magnitude
magnitude level category effects earthquakes per year
less than 1.0 to 2.9 micro generally not felt by people, though recorded on local instruments more than 100,000
3.0–3.9 minor felt by many people; no damage 12,000–100,000
4.0–4.9 light felt by all; minor breakage of objects 2,000–12,000
5.0–5.9 moderate some damage to weak structures 200–2,000
6.0–6.9 strong moderate damage in populated areas 20–200
7.0–7.9 major serious damage over large areas; loss of life 3–20
8.0 and higher great severe destruction and loss of life over large areas fewer than 3
Explanation:
