How long is the richter scale

The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude.

The most recent large earthquake of magnitude 9. Fortunately most earthquakes are extremely small. A majority of quakes register less than 3 on the Richter scale; these tremors, called micro-earthquakes , aren't generally felt by people and are usually recorded only on local seismographs. With every whole point the magnitude rises, the strength of the waves increases tenfold.

Events with magnitudes of about 4. Only a tiny portion of earthquakes 15 or so of the 1. A temblor with a magnitude of 8. The biggest quake in recorded history was the 9.

Generally, you won't see much damage from earthquakes that register below 4 on the Richter scale. Toggle navigation. Get earthquake and tsunami alerts. The downside to the Richter scale is that magnitude is a single number, which cannot fully characterize a complicated phenomenon such as an earthquake. Earthquakes with the same magnitude can differ in many fundamental ways, including the directions of the vibrations, and their relative amplitude at different periods during the tremblor.

These differences can lead to earthquakes with the same magnitude having significantly different levels of destructiveness. Beginning in the mid's, seismologists developed a fairly complete understanding of how a slipping fault generates ground vibrations. An important quantity that characterizes the strength of the faulting is the seismic moment, the algebraic product of the fault area, the fault slip and the stiffness of the surrounding rock.

Generally speaking, an earthquake with large magnitude corresponds to faulting with a large moment, with an increase in one magnitude unit corresponding to an increase of moment by about a factor of But the relationship is inexact, and many cases occur where small faulting causes an unexpectedly large magnitude earthquake or vice versa. Already a subscriber? Sign in. Thanks for reading Scientific American.

Create your free account or Sign in to continue. See Subscription Options. But the Richter scale, denoted by a number called the "magnitude," is the most common. This quantity, which can be read off a seismograph, reflects the amount by which the earth's crust shifts.

The Richter scale has no lower limit and no maximum. The Richter scale is logarithmic , meaning that whole-number jumps indicate a tenfold increase. In this case, the increase is in wave amplitude. That is, the wave amplitude in a level 6 earthquake is 10 times greater than in a level 5 earthquake, and the amplitude increases times between a level 7 earthquake and a level 9 earthquake. The amount of energy released increases As we previously noted, most earthquakes are extremely small.

A majority of quakes register less than 3 on the Richter scale; these tremors, called microquakes , aren't even felt by humans. Only a tiny portion -- 15 or so of the 1.

The biggest quake in recorded history was the 9. Generally, you won't see much damage from earthquakes that register below 4 on the Richter scale. Richter ratings only give you a rough idea of the actual impact of an earthquake, though.