There are two instruments, which are basically the same thing. There is the seismograph , and a more specific tool measures the waves on what is called the Richter scale. Earthquakes are given a number from one to ten, ten being the strongest. The strongest earthquake that their ever was, was measured a 9.3.
an earthquake hazard
9.0
The most accurate measurement of an earthquake's magnitude is typically determined using the moment magnitude scale, which takes into account the total energy released by an earthquake. This measurement provides a more accurate representation of an earthquake's size and severity compared to other scales like the Richter scale.
a seismographic flow
7.4
measurement of the amplitude of the largest seismic waves
6.3
The 2011 Tohoku earthquake measured 9.0 on the Richter scale.
200 miles
Mercalli is a scale for the measurement of earthquake intensities.
an earthquake hazard
An earthquake's magnitude is a measure of how strong it is