Typically, what magnitude does an earthquake have to be for a person to feel it?

Question

Approximately...

Answer 1

If the conditions are right you can feel it at about 3.0. It doesn't cause any damage but you can feel the vibrations.

Answer 2

A magnitude 4 will be felt by most people in the vicinity of an earthquake, and a three may be felt by some people who are close to the epicenter. I've even had occasional reports from people who've felt an earthquake as small as a 2, but they were located nearly right above the earthquake source, and this is very uncommon. Significant damage usually occurs only magnitudes of 5 and up, but this of course depends some on structural stability.

In special situations, such as in mines, even smaller earthquakes can be felt. I work with some people who study very small earthquakes in the gold mines of South Africa. Those quakes are partially caused by the excavation of all the mining tunnels and they can be so smaller that they have negative magnitudes! (Magnitude scales are log scales, so even negative magnitudes doesn't mean that they are un-shaking. It simply means that they are very, very small.) Even though these earthquakes are so small, the are often felt by the miners because they are so close to the faults (sometimes within meters!). Although these tiny "baby" quakes would never cause damage at Earth's surface, they can be disasterous to people inside the mines.

Answer 3

The Richter scale is directly connected with the force released. The shaking will differ from place to place according the distance from epicenter.The proper way to give you an idea of human feeling should be compared only with Mercali scale. I am giving you the force leased equivalent to Richter scale. An rough estimate only says that anything above Richter scale 3 can be felt by human. When you sense the earthquake of magnitude 3 in Richter scale from a distance of 100 K/M from the epicenter the shaking will be 0.1 mm. The shaking will increase by ten fold for each Richter scale and reduced by inverse square of the distance. The Marcali scale is more meaning full but unfortunately not in common use.Its starts from 1 to 12. It varies from place to place for same earthquake. It is decided by its effect only.At 12 everything will be thrown out. In Richter scale we have so far experienced only up to 9.5.
Approximate TNT Yield for Seismic Energy for Richter scale

1 30 lbs
2. 1 ton
3. 29 ton
4. 1000 ton
5. 32000 ton
6. 1 million ton
7. 32 million ton
8. 1 billion ton
9. 32 billion ton
10 1 trillion ton.

Answer 4

3 to 4 on the richter scale and you should feel it. depends also on where you are standing and what you are doing. if you were walking on sand then the chances are you wouldn't feel a 3 earthquake as the sand and walking would nullify the effects.