## Measuring Earthquakes

Magnitude calculations are based on a logarithmic scale, so a ten-fold drop in amplitude decreases the magnitude by 1. If an amplitude of 20 millimetres as measured on a seismic signal corresponds to a magnitude 2 earthquake, then:
There are several ways: a pen drawing an ink line on paper revolving on a drum a light beam making a trace on a moving photographic film
Seismograms are the records (paper copy) produced by seismographs used to calculate the location and
An earthquake cannot physically occur at a depth of 0 km or -1km (above the surface of the earth).
A seismometer is the internal part of the seismograph, which may be a pendulum or a mass mounted on a sp
It is relatively easy to acquire the necessary materials and build your own seismometer. The links here are to various sources with information on how to build a seismometer. They range from very simple and inexpensive to sophisticated and pricey.
The earliest seismoscope was invented by the Chinese philosopher Chang Heng in A.D. 132. This was a large urn on the outside of which were eight dragon heads facing the eight principal directions of the compass.
When an earthquake occurs, it releases energy in the form of seismic waves that radiate from the earthquake so
The Richter scale is not a physical device, but a mathematical formula.
Acceleration is the rate of change in velocity of the ground shaking (how much the velocity changes in a unit time), just as it is the rate of change in the vel