What is the Modified Mercalli Intensity Scale?
The Modified Mercalli Intensity Scale (symbolized as ‘MM’) is a method of rating the intensity of an earthquake. The scale has 12 levels represented by Roman numerals ranging from I to XII and was developed by Harry Wood and Frank Neumann in 1931. The scale is not mathematically defined or measurable by instruments. Rather, it is a subjective measure based on the observed effects of the quake, such as the extent and severity of damage. It is entirely possible for an earthquake of a given magnitude to be rated a different Mercalli rating due to it’s location. In a country such as Japan or the United States, earthquakes do not cause as much damage as the same magnitude earthquake occuring in a place such as Guatemala or Indonesia. This is due primarily to better constuction methods and government mandated building codes. Below is a description of each intensity rating taken from a USGS page describing the Mercalli scale. From http://neic.usgs.gov/neis/general/mercalli.
The Modified Mercalli Intensity Scale (symbolized as ‘MM’) is a method of rating the intensity of an earthquake. The scale has 12 levels represented by Roman numerals ranging from I to XII and was developed by Harry Wood and Frank Neumann in 1931. The scale is not mathematically defined or measurable by instruments. Rather, it is a subjective measure based on the observed effects of the quake, such as the extent and severity of damage. It is entirely possible for an earthquake of a given magnitude to be rated a different Mercalli rating due to it’s location. In a country such as Japan or the United States, earthquakes do not cause as much damage as the same magnitude earthquake occuring in a place such as Guatemala or Indonesia. This is due primarily to better constuction methods and government mandated building codes. Below is a description of each intensity rating taken from a USGS page describing the Mercalli scale.
